Civil Engineering and Architecture

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ISSN 2332-1091

Volume 8 Number 5 2020

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Horizon Research Publishing http://www.hrpub.org

ISSN 2332-1091 Table of Contents

Civil Engineering and Architecture

Volume 8 Number 5 2020

Compliance of High-rise Buildings Vertical Accessibility Components with Universal Design Strategies: A Case

Study of Covenant University, Ota, Nigeria

(https://www.doi.org/10.13189/cea.2020.080501)

Sholanke A. B., Adelowo I. E., Gbotosho J. O. ........................................................................................................... 735

The Occupational Health and Safety Effect on Road Construction Worker Performance


Fourry Handoko, Maranatha Wijayaningtyas, Imam H. A. Kusuma, Sutanto Hidayat, A. Ismail, Z. Abdullah .......... 750

A Structural Format to Facilitate User Input for the Co-design of a Cardiac Health Unit


Tanut Waroonkun ......................................................................................................................................................... 760

Performance of CO2 Cured Sugar Cane Bagasse Ash Concrete in Marine Environment


T. Santhosh Kumar, Balaji K. V. G. D, Ch. Sandeep Reddy, K. Chitti Babu, Ch. Lakshmi Sowjanya ....................... 771

Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in Developing Countries


Udomiaye Emmanuel, Chukwuali Basil Chukwuemeka, Kalu Cheche Kalu ............................................................. 777

Air Temperature Analysis of a Residential House Using Soliworks Flow Simulation


Estrella C. Macabutas, Alejandro F. Tongco ................................................................................................................ 792

An Alternative Approach in Assessing Visual Comfort Based on Students' Perceptions in Daylit Classrooms in the

Tropics


Irnawaty Idrus, Ramli Rahim, Baharuddin Hamzah, Nurul Jamala ............................................................................ 801

A Study on Mechanical and Durability Aspects of Concrete Modified with Steel Fibers (SFs)


Jawad Ahmad, Aneel Manan, Asif Ali, M. Waleed Khan, M. Asim, Osama Zaid ....................................................... 814

Evaluation of Ventilation System Efficiency with Reference to Ceiling Height in Warm-Humid Climate of Pakistan


Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal .................................................................................................. 824

Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia


Mithen Lullulangi, Armiwaty Tawani, Rahmansah ..................................................................................................... 832

Experimental Investigation on Augmenting the Discharge over Ogee Spillways with Nanocement


N. Muthukumaran, G. Prince Arulraj .......................................................................................................................... 838

Integrating Cultural Change Management Program with Smart Workplace Transformation and Refurbishment

Project Schedule


Sefik Emre Ulukan ...................................................................................................................................................... 847

Assessment of Quality of Life in the Urban Environment; Case Study: Famagusta, N. Cyprus


Mojdeh Nikoofam, Abdollah Mobaraki....................................................................................................................... 860

A Quest on the Role of Aesthetics in Enhancing Functionality of Urban Planning


Hourakhsh Ahmad Nia, Fashuyi Olugbenga ............................................................................................................... 873

Borders (in between): A City within a City Decoding Different Morphologies of Fragmented Housing


Hatice Kalfaoglu Hatipoglu, Seher Beyza Mahmut .................................................................................................... 880

The Impact of Transparency Ratio on Thermal Comfort: A Field Study on Educational Building


Fatma Zoroğlu Çağlar, Gülay Zorer Gedik, Hüseyin Gökdemir ................................................................................. 890

Socio-economic and Geo-political Transitions in the Mediterranean Basin and Its Impact on Urban Forms of Port

Cities


Husam R. Husain, Hassina Nafa .................................................................................................................................. 898

Regeneration as a Tool for Enhancing Vitality of Urban Spaces


Rokhsaneh Rahbarianyazd........................................................................................................................................... 908

The Effect of Centrality Values in Urban Gentrification Development: A Case Study of Erbil City


Mustafa Aziz Amen, Hourakhsh A. Nia ...................................................................................................................... 916

The Cognition of the Architectural Styles Role on Thermal Performance in Houses of Semi-Arid Climates: Analysis

of Building Envelope Materials


Maryam Iranfar, Salar Salah Muhy Al-Din ................................................................................................................. 929

An Experimental Approach to the Sophomore Architectural Design Studio


Milorad Pavlovic ......................................................................................................................................................... 924

Habitability, a Basic Premise for Home Design and Its Impact on the Curricula of Architecture Schools


Gildardo Herrera-Sánchez, Victor Manuel Garcia-Izaguirre ....................................................................................... 950

Ultra-Lightweight EPS Concrete: Mixing Procedure and Predictive Models for Compressive Strength


Fayez Moutassem ........................................................................................................................................................ 963

Numerical Simulation of Acoustic Equation Using Radial Point Interpolation Method with Discontinuous Galerkin

Time Integration


Kresno WS, SPR Wardani, E Susila, Pranowo ............................................................................................................ 973

Typology of Peri-Urban Area Based on Physical and Social Aspects in Marisa, Indonesia


Irwan Wunarlan, Sugiono Soetomo, Iwan Rudiarto .................................................................................................... 984

Characterizations and Modeling the Influence of Particle Size Distributions (PSD) of Glass Powder on the

Mechanical Behavior of Normal Strength Concrete


Brwa Omer, Jalal Saeed ............................................................................................................................................... 993

Development of Freeway Weaving Areas Microsimulation Model (FWASIM)


Mahdi Alkubaisi ........................................................................................................................................................ 1006

Analysis of Interior Design of Restaurants with Reference to Ambience and Customer Gratification


Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal ................................................................................................ 1019

Evaluation of Mechanical and Durability Performance of Coir Pith Ash Blended Cement Concrete


Balagopal V, Viswanathan T. S .................................................................................................................................. 1028

Variations in Mass and Resistance Due to Accelerated Weathering Effects in Concrete Specimens Used in

Low-income Housing


Aurora Martínez-Loaiza, María Teresa Sánchez-Medrano ........................................................................................ 1039

Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for Marine

Structures


Trong-Phuoc Huynh, Phuc-Huynh Bui, Nguyen-Trong Ho, Phuong-Trinh Bui ....................................................... 1047

Effect of Metakaolin and Condensed Silica Fume on the Rheological and Structural Properties of Self-compacting

Concrete


S.Vijaya Kumar, B.Dean Kumar, B L P Swami ......................................................................................................... 1057

Determination of Black Site Area Based on Equivalent Accident Number Analysis: Case Study National Roads in

Ambon City


Lenora Leuhery, Hamkah .......................................................................................................................................... 1063

Study on Using Fly Ash for Fly Ash - Soil Piles in Reinforcing Soft Ground


Tuan Anh Nguyen, Dat Thanh Nguyen, Tung Thanh Pham, Linh Truong Chau ....................................................... 1074

Study on Response of G+5 Symmetric Structure Subjected to Blast Loads


I Krishna Chaitanya, Balaji K. V. G. D, M. Pavan Kumar, B. Sudeepthi .................................................................. 1086

A Design Proposal of Integrated Smart Mobility Application for Travel Behavior Change towards Sustainable

Mobility


Gülce Kırdar, Sabiha İrem Ardıç ............................................................................................................................... 1095

Housing Dilemma and Vertical Dimensions


Muhiuddin Bahauddin Yusuf, Islam H. Elghonaimoy ............................................................................................... 1107

Compressive Behaviour of Circular, Square, and Rectangular Concrete-Filled Steel Tube Stub Columns


Alireza Bahrami, Ali Mahmoudi Kouhi .................................................................................................................... 1119

Sustainable Hospital Architecture - Potential of Underground Spaces


Irina Bulakh, Iryna Merylova .................................................................................................................................... 1127

Recycled Aggregate Concrete Made with Silica Fume: Experimental Investigation


Ayser J. Ismail, Khaleel H. Younis, Shelan M. Maruf ............................................................................................... 1136

Civil Engineering and Architecture 8(5): 735-749, 2020 http://www.hrpub.org

DOI: 10.13189/cea.2020.080501

Compliance of High-rise Buildings Vertical Accessibility

Components with Universal Design Strategies: A Case

Study of Covenant University, Ota, Nigeria

Sholanke A. B., Adelowo I. E.*, Gbotosho J. O.

Department of Architecture, College of Science and Technology, Covenant University, Ota, Nigeria

Received May 16, 2020; Revised July 2, 2020; Accepted July 20, 2020

Cite This Paper in the following Citation Styles

(a): [1] Sholanke A. B., Adelowo I. E., Gbotosho J. O. , "Compliance of High-rise Buildings Vertical Accessibility

Components with Universal Design Strategies: A Case Study of Covenant University, Ota, Nigeria," Civil Engineering

and Architecture, Vol. 8, No. 5, pp. 735 - 749, 2020. DOI: 10.13189/cea.2020.080501.

(b): Sholanke A. B., Adelowo I. E., Gbotosho J. O. (2020). Compliance of High-rise Buildings Vertical Accessibility

Components with Universal Design Strategies: A Case Study of Covenant University, Ota, Nigeria. Civil Engineering and

Architecture, 8(5), 735 - 749. DOI: 10.13189/cea.2020.080501.

Copyright©2020 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License

Abstract In recent times, with the increase in

population, land areas that can accommodate the traditional

school design model are becoming difficult to come by in

urban areas or expensive. Therefore, for urban schools to

accommodate the increasing population, school designs

have shifted from outward horizontal arrangements to

upward vertical designs. Consequently, this study

examined the compliance of vertical accessibility

components in high-rise buildings in Covenant University,

Ota in Nigeria, with universal design strategies, with a

view to identifying areas for further improvements,

towards contributing to ways of promoting social inclusion

in educational environments. The research is a qualitative

case study of a tertiary institution that investigated two

high-rise buildings on the university campus. An

observation guide developed for the study and a digital

camera were used to collect primary field data. The data

were content analysed and presented using descriptive

approach with the aid of texts and pictures. The findings

revealed that ramps, steps/staircases and lifts are the

vertical accessibility components provided in the high-rise

buildings, all of which were found to exhibit various levels

of inconsistencies with universal design strategies. One of

the key recommendations of the study is to retrofit the

buildings with necessary accessible features where they are

lacking or inappropriately provided, where possible. The

study will be useful to researchers, students, educators,

policy makers and building design professionals in

addressing issues relating to universal design of the built

environment, particularly as it relates to the provision of

equitable vertical movement features in high-rise public

buildings.

Keywords Universal Design, High-rise Buildings,

Accessibility, Usability, Vertical Movement Components,

Covenant University

1. Introduction

In recent times, many families have migrated to urban

centres, as it is becoming more desirable to live in urban

areas that provide people with varieties of amenities,

facilities and services for improving quality of living. One

of such conveniences is the availability of good schools. It

is however observed that not every pupil that leaves

secondary school in urban areas move on to a tertiary

institution. A sizeable number of students in this category

are those with disabilities, as a sizable population of people

in Nigeria are living with a form of disability. Though it

can be argued that there are established special schools that

can cater for the peculiar needs of the physically

challenged, this does not imply that regular schools should

not be readily available and accessible to this user group. A

school ought to be a citadel of learning where people of

736 Compliance of High-rise Buildings Vertical Accessibility Components with Universal

Design Strategies: A Case Study of Covenant University, Ota, Nigeria

diverse background can come together to learn and acquire

formal education, regardless of their gender, race, color,

ability or disability.

With the emergence of globalisation that comes with

population explosion in urban areas, land areas that can

support and accommodate the traditional horizontal school

design model are no longer readily affordable and

financially viable. Therefore, for urban schools to

accommodate the increasing population, Hadley [1]

advanced that school designs must move from designing

outward to designing upward. Consequently, many school

buildings are now being designed vertically (upwards) as

high-rise buildings, rather than spreading horizontally

(outwards). With the emergence of this new model of

school buildings, the demand for vertical movement

provisions that can cater for the accessibility and usability

needs of everyone, is considered fundamental to making

university education equitable and inclusively available,

accessible and usable to anyone that can afford it.

In an academic environment, it is imperative to provide a

barrier free setting for all students to enable them

experience and benefit from all aspects of education within

the learning environment. Universal Design (UD) has the

capacity to change the status quo of universities into

institutions that provide users with equal opportunities to

learn, excel and attain their true prospects, despite

prevailing circumstances of age, size or physical capability

[2]. The UD ideology advocates the design of products and

the built environment to be accessible and usable by all

category of users without any need for adaptation or a

special kind of design solution [3]. In an academic

environment, a key factor that contributes to a barrier free

setting is the provision of appropriate accessibility and

usability features. With the emergence of vertical school

buildings, it is important that all necessary features that can

make school buildings universally accessible to all are in

place. The facilities, including vertical movement

components, should meet the needs of all user categories,

regardless of their ability or inability. To ascertain that

academic settings are inclusive in nature with regards to the

provision of accessibility components, there is a need to

investigate existing schools to establish the conformity of

their accessibility features with UD strategies, towards

pinpointing areas for enhancements.

Covenant University has attained the status of a highly

regarded university in Nigeria and Africa. The institution is

working towards becoming one of the top ten high-level

universities in the world [3], in accordance with vision

102022 proclaimed by the Chancellor of the university,

Bishop (Dr.) David Oyedepo in 2012. To be one of the best

universities in the world will require that the institution’s

buildings and environment are accessible and usable for

everyone in line with the UD ideology. It is on this note,

that this study investigated the compliance of vertical

accessibility components of high-rise buildings with UD

strategies in the university, with a view to identifying areas

for further improvements, towards contributing to ways of

promoting social inclusion in educational environments.

Covenant University was selected as the study location,

due to its rating as the best ranked university in Nigeria in

the 2020 Times Higher Education World Rankings of

Universities [4].

The scope of the study is limited to investigating only

the general vertical movement components provided for

users of high-rise buildings in the university. The vertical

movement features were specifically targeted as the focus

of the investigation, because they require more special

considerations to make them usable for everyone,

compared to horizontal movement features, whose

principal requirement is the provision of adequate space

that can allow for mass movement or at least allow two

wheelchair users pass side by side.

Some of those who will find the study a useful reference

document, are: researchers, students, educators, policy

makers and building design professionals. The findings of

the study will also be useful for benchmarking Covenant

University’s high-rise buildings compliance level with UD

strategies, against those of other institutions in Nigeria and

around the globe. The structure of the paper comprises of

an abstract, an introduction, a literature review, a

methodology, a presentation of the analysed field data with

a discussion of findings, as well as a conclusion,

acknowledgements and references sections. Field data for

the study was gathered between December 2019 and

February 2020.

2. Literature Review

2.1. Universal Design Paradigm

In the past, design professionals did not realise that

when physically challenged persons encounter an obstacle,

it makes them handicapped [5]. Diversity in humans is not

a new knowledge as each person is uniquely different

from the other and as time goes on, we are subject to more

changes that lead to more diversity. There are a lot of

things that separate us from one another. Some of these

things include: gender, race, background, color, abilities

or disabilities. Therefore, it is very important to create a

world where every person can feel accepted and everyone

has equal rights to all facilities and opportunities [6].

UD is a design concept that aims to cater for the needs

of every person regardless of their abilities at little or no

extra cost. It is defined as the design of environments,

buildings and products to be utilised by everyone without

requiring any modification or specialised design. UD is

both sustainable and cost effective, as it is targeted at

designing for every individual. It also helps to reduce cost

when considered at the beginning of the design process,

rather than when the need arises after a building has been

built [7]. UD is a useful concept for enhancing learning

for students with disabilities. The promotion of UD in the

education sector has led to the development of specially

Civil Engineering and Architecture 8(5): 735-749, 2020 737

designed hardware and software applications for

enhancing learning for the physically challenged [8].

According to a global assessment on topics pertaining

to disability issued in 2011, over 25 million Nigerians

have at least a disability, with about 3.6 million of them

having difficulties functioning normally. This means that

a large population of the society is living with disabilities

in the country. This makes it important for buildings to be

designed to accommodate the special needs of this user

group in line with the UD ideology. UD is similar to

accessible design, but in actual sense, it is a better

alternative to it. While accessible design seeks to promote

accessibility for people with disabilities (PWDs), UD

seeks to promote and cater for the needs of everyone

regardless of their abilities or inabilities [9,10].

According to Sholanke, Adeboye, Alagbe, Fadipe &

Iyoha [11] and Copeland [12], UD is generally guided by

seven principles proposed by the Centre for UD in North

Carolina State University in America. The principles are:

1) Equitable Use: The design strategy should be of value

and sought-after by any user group. 2) Flexibility in Use:

Diversity of individual preference and skill should be

reminiscent of the design. 3) Simple and Intuitive Use:

The design should be easily understood without the need

for conscious reasoning by the user. 4) Perceptible

Information: The sensory input of the user should not

hinder the ability of the design to transmit or pass

information effectively to the user. 5) Tolerance for Error:

The design should limit the possibility of occurring

unintentional or unwanted acts. 6) Low Physical Effort:

The design should require minimal physical effort to use

and promote user comfort. 7) Size and Space for

Approach and Use: The size and space allocated for

approach, manipulation, reach and use of the design

should be reasonable to allow for easy access regardless

of the size, posture or mobility of the user.

The UD principles can be used for guiding and

influencing a design procedure and concede the indication

of disposable products and environments, as well as to

evaluate existing architectural designs [9, 3]. Where UD is

applied at the design stage, its outcome benefits everyone

as it accommodates user’s diversity. For instance, it helps

to create an environment that allows people to age, yet

retain their independence. It also helps businesses have an

edge over their counterparts. Nevertheless, some people

still fail to fully implement UD criteria into designs

because of some misconceptions about the idea. Two of

these misconceptions identified by Rossetti [13] are that

buildings that are universally designed appear unpleasant

and conventional, as well as people getting the wrong

impression that such buildings are planned solely for the

handicapped. The author argued that these are false

impressions, as UD features enhance the beauty of a

building while making it functional and convenient for

every user, rather than the physically challenged alone.

What is convenient for a physically challenged person to

access and use will most certainly be easily accessible and

usable for able-bodied persons.

Rossetti [13] also corrected another delusion that a

building that conforms with UD principles costs more,

because of the distinctive features of UD present in the

building. The author debunked this notion by arguing that

a building that complies with UD concept stands to be

valuable for a lifetime, thereby increasing the value of the

building which makes it useful for as long as the building

is in use. Also, people often think that a building designed

with UD parameters requires more square footage. This

the author also debunked by explaining that space

planning is important in design, therefore, a universally

designed building does not require more square footage

outside just adequate room for navigation. The last

mistaken belief identified by Rossetti [13] is that the

adoption of UD strategies in a building makes it less

likely to scale a building code scrutiny. The author

clarified that based on the definition and nature of UD, its

principles always adhere to established state and federal

building codes. In cases of inquiry that may arise from the

evaluation of the design, provision for local variation is

usually made available.

Notwithstanding the various misconceptions

surrounding UD ideology, the concept is considered

significant to humans and has therefore gained global

recognition and caught many researchers’ interests lately.

For instance, Sholanke, Adeboye & Alagbe [9]

investigated designs that constituted barriers to achieving

UD in selected academic buildings in selected universities

in Ogun State, Nigeria. The study is a qualitative survey

that used observation guide and pictures to collect field

data from nine academic buildings across three

universities in the study area. The designed features found

to constitute barriers to achieving UD in the various

academic buildings in the selected universities were

mainly accessibility features that are not suitable for the

use of the physically challenged. Some of such features

include: lack of dropped kerbs to external walkways and

open drainage beside walkways, lack of accessible

parking spaces, inadequate doors, steps, ramps, handrails

and access routes dimensions, and provision of steps

without ramps where there are changes in levels.

Likewise, Hibatullah [14] evaluated the accessibility

components of the School of Engineering buildings at the

University of Jordan. The researcher carried out the study

in order to examine the level of accessibility in existing

higher learning institutions that are in accordance with

Jordanian Nation Building Codes - Building Requirement

Code for the Disabled (BRCD), towards the promotion of

the “right to work” and the “right to get higher education”

for PWDs in line with the UD ideology. The study is a

qualitative research that utilised interviews with students

and staff members with disabilities to gather data. To

investigate if the requirements for renovation in public

buildings and education buildings implement the BRCD,



an observation guide was used to collect data. The result

of the study revealed that the BRCD requirements did not

cater for the minimum requests of PWDs, because the

BRCD was mainly concerned with people with physical

disabilities, with less consideration made for people living

with hearing or visual impairment.

In addition, Ibem, Oni, Umoren & Ejiga [15] appraised

the UD compliance of museum buildings in Southwest

Nigeria. The authors conducted their research to

determine how the design, planning and construction of

selected museum buildings and facilities complied with

the principles of UD and how they promoted the

satisfaction of users in the study area. The study is a

multiple case study research that used observation guide

to gather field data from three museums in Southwest

Nigeria. The museums were appraised based on three

principles of UD which are: accessibility, approachability

and usability. The result showed that all the museums

complied with the approachability principle, but fell short

in accessibility and usability requirements.

Similarly, in a study by Sholanke, Adeboye, Oluwatayo

& Alagbe [3], the researchers used the seven principles of

UD developed by The Center for Universal Design in

North Carolina State University to assess the features of

the main entrances of five selected public buildings in

Covenant University, Ota in Nigeria. The features

assessed include: carparks, pedestrian walkways, entrance

porches, entrance steps, entrance ramps, floor finishes and

entrance doors. The result indicated that all the buildings

fell short of meeting UD accessibility requirements. For

instance, ramps were not provided alongside steps at the

main entrances of majority of the buildings in line with

the demand of UD. Where a ramp was found, such ramp

did not conform with UD standard. Also, several steps

situated at the main entrances of the buildings were found

to be inconsistent with UD requirements.

Furthermore, a UD study that centred around the

everyday life of elderly adults in an adult home was

conducted by Mustaquim [16]. The research was carried

out to gain insight into the performance of the different

variables associated with the UD concept and how the

elderly adults identified with them in their day to day

activities in the home. The study employed quantitative

means to gather data in Montgomery County's Arcola

Health and Rehab Centre, Maryland, USA, over a period

of four weeks. A total of thirty-one patients, purposively

selected based on their cognitive abilities, took part in the

survey. The result showed that UD variables that defined

knowledge acquisition present a substantial modification

in its description, through the parameters that describe

perception. The result also underscored the significance of

understanding the UD principles, which was discovered

not to be adequate for the design of suitable homes that

are inclusive and accessible for elderly adults. Though the

study met its target, being a case study of a single adult

home means that the result cannot be generalised.

Also, a UD interior design application study was

conducted in shopping malls in Surabaya by Yusita, Yong

& Thamrin [17]. The study was carried out to identify

challenges associated with entrance and circulation

facilities, with a view to address the design challenges that

may arise in shopping centres around Surabaya. The study

employed qualitative research methodology. Data was

collected from fifteen malls in the study area. The malls

were selected based on the following criteria: mall

diversity, location distribution, popularity and the

establishment distribution. Observation and

documentation were used to gather field data. A

significant problem discovered in most of the malls was

lack of ramped access at their entrances. And where ramps

were found, such ramps lacked handrails in line with a

key UD requirement. The research findings indicated that

the accessibility needs of the physically challenged was

not given enough attention in the development of the

shopping malls.

In addition, Kadir & Jamaludin [18] investigated the

level of implementation of Malaysian standards and UD in

structures accessible by the public in Putrajaya. The

evaluation was based on ability of the facilities provided

to attain the standard of existing requirements and

guidelines applicable to Malaysia. The research is a case

study that employed qualitative research approaches. The

five buildings that were assessed for the purpose of the

study were chosen based on how frequent they are visited.

The buildings include: a government administrative office,

an educational foundation, a health service centre, a

conference/event centre and a worship centre. The study

found that the only thing that was lacking in the buildings

is the absence of appropriate accessibility features to the

information counter.

Generally, previous UD studies found that center

around the physical environment, established that little or

no consideration were made for accessibility and usability

features that meet the needs of PWDs in majority of the

buildings investigated. It was also observed from most of

the studies that the focus of the researchers, was mainly

on low-rise public buildings. Hence, there is a dearth of

detailed information on the UD compliance level of

vertical accessibility components in high-rise buildings,

particularly in academic environments in Nigeria. Due to

the peculiar nature of high-rise buildings, it is imperative

that their vertical movement provisions conform with UD

requirements in academic settings, towards promoting

inclusive education. Though Sholanke et al. [9] and

Hibatullah [14] investigated accessibility in some

academic buildings in university environments in Nigeria

and Jordan respectively, the buildings the researchers

examined are mainly low-rise buildings. This did not

provide the necessary feedback on the UD compliance

level of accessibility components such as lifts that are

mainly a requirement in high-rise buildings in the study

areas. Consequently, this study was conceived to fill this

gap by investigating the UD compliance level of vertical


accessibility components of high-rise buildings in

Covenant University, Ota, Nigeria, with a view to identify

areas for possible improvement, towards making

contributions on ways of promoting social inclusion in

educational environments in Nigeria.

2.2. Accessibility in High-rise Buildings

The criteria used to define a high-rise building vary

across the globe. The Building Code of Hyderabad, India

highlighted the requirements for a high-rise building as

having at least four floors, or fifteen to eighteen meters or

more in height [19]. Emporis Standards [20] defined a high

rise as a multi-story structure between thirty-five to

hundred meters high, or a building whose altitude is not

determined, but is in the range of twelve to thirty-nine

floors. In the United States, National Fire Protection

Association (NFPA) [21] described a high-rise as a

building higher than seventy-five feet (twenty-three

meters), or about seven storeys. However, according to the

National Building Code [22] used in Nigeria, any building

that is more than four floors is classified as a high-rise

building in the country. Such a building is expected to be

provided with specialised feature for vertical movement

that will accommodate the accessibility and usability needs

of everyone, including the physically challenged.

Accessibility, basically covers the extent to which a

building’s point of entry provides ease of movement to the

users, with the inclusion of people with physical

disabilities into the spaces and facilities within the building,

in order to enable them perform obligatory activities and

functions. Generally, vertical movement components used

in public buildings include: stairs, ramps, lifts, escalators

and travellators. The most common of these lots are stairs,

ramps and lifts. The three accessibility components are

generally used in most high-rise buildings for easy vertical

movement of users, especially in academic environments.

2.3. Vertical Accessibility Components Universal

Design Strategies in Academic Environments

The usual vertical accessibility components that are

generally provided in academic environments include:

stairs, ramps and lifts. Each of these access features have

specific standard requirements, in order to enable them

cater for the accessibility needs of every user that intends

to use any of them to access a building, irrespective of the

user’s age or disability. Vertical movements in a building

can be classified into two categories. The first is where

there is a change in level on a level plane on a floor, while

the second is moving from one floor to another [23-25].

A Universal Design Handbook, Building for Everyone

[26] provided useful guidelines for the design of stairs,

ramps and lifts. The provisions of the guidelines are as

follows:

2.3.1. Staircases

Staircases or stairs can be used as a means of vertical

movement in buildings when there is a change in level on

the level plane which is often the entrance to a building, or

from one floor to another. There are various specifications

that must be followed in order to design stairs that can be

accessible and usable to most user groups. Key among

these specifications include:

(1) The dimension of a stair must be consistent throughout

its flight with tread and going dimensions ranging

from 300 mm – 450 mm and riser dimensions ranging

from 150 mm – 180 mm.

(2) The face of the riser should not be less than 60o.

(3) Step risers should be rigid, since open risers can cause

visual discomfort.

(4) The clear dimension of the inner stairs, which is

measured between the handrails, should not be less

than 1200 mm.

(5) The total height of a step flight between landings

should not surpass 1800 mm.

(6) Stairs with two or more successive flights should

ensure that the number of steps in each flight are as the

same as possible.

(7) Stairs which are not enclosed should be put directly in

line with a corridor or main circulation path.

(8) Stairs that are enclosed should continuously provide

signs and directions that lead to the stairs.

(9) Railings attached to stairs should be placed 900 mm –

1100 mm above the landings and above the stairs.

(10) Stairs that are enclosed should continuously provide

signs and directions that lead to the stairs.

(11) Railings attached to stairs should be placed 900 mm –

1100 mm above the landings and above the stairs.

The aforementioned requirements for the design of an

accessible stairs are illustrated in Figures 1 and 2 with all

dimensions in millimeters.

Source: Building for Everyone [26].

Figure 1. Stairs Details




Figure 2. Handrails Details

2.3.2. Ramps

Ramps are mainly used as means of vertical movement

when there is an alteration in level on the level plane.

They can be used when there is a change in floor for very

large buildings. In such a case, they require a large space

to be very effective. However, ramps should be

accompanied with stairs except in situations where the

difference between the ground level and the level of the

building is less than 300 mm.

Ramps are more effective than stairs when entering into

a building as they cater for the aged, the physically

challenged and other categories of users. The following

considerations should be put in place when designing an

accessible ramp that can be usable for everyone:

i. Ramps should have a slope not greater than 1 to

20.

ii. The maximum rise between the landings should be

450 mm.

iii. The maximum length of a ramp should be 9000

mm in accordance to the 1 to 20 gradient.

iv. When there are two consecutive ramps, they

should be of the same slope and gradient.

v. It is important to avoid ramps with steeper

gradients as they are dangerous to users.

vi. The distance between the low rail and the ramp is

between 600 mm – 750 mm, whereas the distance

between the top rail and the landing is between

900 mm – 1000 mm.

The stated requirements for the design of accessible

ramps are illustrated in Figure 3 with all dimensions in

millimeters.


Figure 3. Ramp Details

2.3.3. Lifts

Lifts or Elevators are the most convenient means of

passage from one floor to another for people that do not

want to use staircases, especially in high-rise buildings.

Lifts are mechanical devices that rely strictly on regular

supply of electricity to function and be effective in a

building. The following factors should be considered in the

design of lifts:

Lifts should permanently be positioned opposite

stairways in a building to provide users an alternative

means of passage. The location is important for users

who are not fully comfortable using the lifts and

want to access other floors easily.

The location of lifts should be visibly indicated with

signs from the entrance and other vital areas inside a

building for easy direction.

Lifts provided in public places should be able to

accommodate people travelling with luggage.

Lifts should have minimum internal dimensions of

1800 mm by 1800 mm.

Lift doors should be as wide as 950 mm to

accommodate every category of user.

Lift doors ought to open for at least 8 seconds to

allow everyone exiting and entering the lift do so

conveniently.

There should be an obvious visual contrast between

the lift door and the adjacent wall surfaces.

Figure 4 shows an illustration of the requirements of an

accessible lift with all dimensions in millimeters.



Figure 4. Lift Details

3. Methodology

The research is a case study of Covenant University, Ota

in Nigeria, with a focus on high-rise buildings vertical

movement components. The case study approach was

considered suitable for carrying out the research, because

the research was targeted at unfolding an existing situation.

According to Yin [27], case study can be categorised into

three: explanatory, exploratory and descriptive. All these

approaches help to provide answers to research questions

of how and why. Noor [28] explained that the purpose of a

case study is not to examine the organisation as a whole,

but direct the centre of interest to a specific area, feature or

unit of analysis, in this case a university setting. As the

study was out to compare what is existing to known

standards, qualitative research methodology was

considered the most appropriate method to execute the

research and was employed. The study was targeted at

evaluating the compliance level of vertical accessibility

components in high-rise buildings with UD strategies. This

necessitated the examination of what is existing in the

selected buildings and the findings compared with UD

strategies found in literature. According to Sholanke,

Adeboye & Alagbe [29], it is appropriate to use qualitative

research methodology where the purpose of a research

centres around examining, understanding and describing a

phenomenon. Qualitative research approach is usually

useful for investigating and unfolding the truth about the

state of a situation, event or an item as is the case with this

study.

To gather field data for the research, a thematic textual

analysis of known UD strategies in literature was first

conducted to collect secondary data that was used to

develop an observation guide. The secondary data were

collected from relevant published literature that were

sourced for with the aid of Google search engine via the

internet. Key among such literature are: the seven

principles of UD developed by the Centre for UD in North

Carolina State University in America, the Building for

Everyone [26], as well as a PhD thesis by Sholanke [30] on

UD compliance of academic buildings in Ogun State,

Nigeria. The secondary data was analysed by textual

analysis to sieve out relevant information that was useful

for the development of the observation schedule. Based on

the criteria used to judge high-rise buildings in Nigeria

specified in the National Building code [22] mentioned

earlier, only two buildings in the university campus fall

under the category of high-rise buildings. The two

buildings that constitute the study population of high-rise

buildings are: The Senate Building with eight floors; and

The Centre for Research, Innovation and Discovery

Building, made up of seven floors. Because the study

population is just two buildings, both buildings were

adopted as the sample size and used for the research.

The study was designed as a qualitative research, hence

all the data gathered, analysed and presented are qualitative

in nature. Primary field data were gathered from the two

buildings that constitute the sample size by the aid of the

observation guide developed for the study, as well as

pictures taken with a digital camera to document the

findings and enrich data collected with the observation

guide. The primary data obtained from the buildings were

those pertaining to the vertical accessibility components.

The data were content analysed and grouped in themes.

The analysis involved comparing the data obtained with

known UD standard strategies mentioned earlier to

determine their compliance level with the standards. The

findings of the research are presented using descriptive

approach with texts and pictures in accordance with

qualitative research methodology of this nature. The

primary field data collected from the two buildings were

gathered between December 2019 and February 2020 as

earlier mentioned.

4. Result, Analysis and Discussion



4.1. Senate Building

The Senate Building in Covenant University serves as

the main administrative building for the university. It was

commissioned on March 17, 2013 by the Chancellor,

Bishop (Dr.) David Oyedepo. The building houses the

Senate Chamber of the university as well as offices for the

Chancellor, Vice Chancellor, Registrar, Consultancy and

Financial Services. The building is made up of eight

floors, making it the tallest building in the university

campus. The vertical accessibility components found in

the building are ramps, steps/staircases and lifts. These

features are examined in the following sections.

4.1.1. Main Entrance Stairs and Ramps

At the main entrance of the Senate building, both ramps

and steps are provided as vertical movement components

for users to access the building at the main entrance of the

building in conformity with UD requirement, as shown in

Plates 1A and 1B.

(A)

(B)

Plates 1A and 1B. Senate Building Main Entrance Ramps and Steps

Each of the ramps at the main entrance of the Senate

building are positioned on either side of the steps at the

main entrance, as shown in Plates 1A and 1B. The surfaces

of the ramps and step treads are finished with polished

granite which are firm, hard and ordinarily non-slippery.

However, polished granite is not suitable for outdoor floor

spaces due to their slippery nature when they get wet. The

steps and ramps surfaces can become slippery and unsafe

to use when wet during raining season. This contravenes

the safety standard of the UD principles which requires

features to be safe to use for users at all times. The height of

the ramps is 540 mm, but the ramp to the right-side of the

step is 3130 mm long, while the one on the left-side is 2800

mm in length. This shows inconsistency in the gradient of

the ramp, contrary to UD requirement. Also, the slopes of

both ramps are too steep. Their gradients are far higher than

the 1 to 20 minimum standard specified for accessible

ramps. This makes the ramps uncomfortable and unsafe to

use. The effective widths of the ramps which are, 1050 mm

and 1100 mm also fall short of the minimum acceptable of

1200 mm for a one-way accessible ramp. The widths are

narrow and not suitable for a wheelchair user to

conveniently navigate through. In addition, the ramps are

not provided with a handrail on either side for the use of

those who might need to support themselves while using

the ramps in line with UD requirements. Generally, the

specifications of both ramps at the entrance of the Senate

building fall short of the requirements for an accessible

ramp. Their compliance level with UD strategies is low.

Likewise, the UD compliance level of the steps at the main

entrance of the building is also low. This is because the

dimensions of both the step risers (190 mm) and tread (900

mm) are outside the acceptable limit of 180 mm and 450

mm respectively. The minimum effective width of the

steps is 4600 mm. Due to the large span, this requires that

at least one handrail be provided for those who have

mobility difficulty to support themselves when climbing or

descending the steps. However, no handrail was provided.

Also, the treads surfaces may become unsafe when wet as

earlier mentioned. Nevertheless, the steps have closed

risers which makes them safe to use, especially when dry,

as a foot cannot slip through them.

4.1.2. General Access Staircase

The Senate building is provided with two internal access

staircases. The first one is a general access staircase located

at the far left of the main entrance hall and the second is a

service and emergency exit staircase situated at the rear end

of the building. The two staircases are dog-leg stairs. As

the focus of the study is on the main staircase used in

high-rise buildings, only the general access stairs were

examined. Plates 2A and 2B are pictorial images of the

general access staircase showing the various components

of the stairs.


(A) (B)

Plates 2A and 2B. Senate Building General Access Staircase

The general access staircase is a concrete stair finished

with polished granite as shown in Plates 2A and 2B. The

risers of the stairs are 160 mm high and generally

consistent across the floors in line with UD requirement.

Usually stairs risers are expected to be consistent and have

heights between 150 mm and 180 mm. The risers are

closed risers which are safe for users as a foot cannot

mistakenly slip through them. The treads of the stairs are

290 mm wide and consistent. Though this dimension is

slightly short of the 300 mm minimum standard

requirement for a step, the difference of 100 mm is

considered insignificant to impact negatively on users’

convenience. Moreover, the treads are generally consistent

in size. The surfaces of the treads and landings of the

staircase are also firm, hard and non-slippery in line with

UD requirements. The effective width of the stairs and

landings is 1400 mm which is wider than the minimum

requirement of 1200 mm for passage ways. The widths are

large enough to allow two or more people to pass side by

side. The height of floors to landings is approximately 1800

mm, which is the minimum acceptable requirement in this

regard, hence adequate. Each flight of the stairs is made up

of an average of 12 risers. This falls within the maximum

acceptable limit of 15 steps per flight. The staircases are

provided with round stainless-steel handrails on both sides.

The handrails height is approximately 950 mm from the

surface of the treads. This dimension conforms with the

acceptable height range specified for accessible handrails

which is between 900 mm and 1000 mm. The diameter of

the handrails is 50 mm and conforms with the minimum

acceptable diameter of 60 mm specified for accessible

designs. However, a lower handrail was not provided for

people of short status and children, in line with UD

requirements. Nevertheless, based on the overall findings

on the general access staircase in the building, its

compliance level with UD parameters is high.

4.1.3. General Passenger Lift

Whereas the general access staircase of the Senate

building is located to the far left within the main entrance

hall, the only general passenger lift in the building is

positioned to the opposite far right of the main entrance

hall as shown in Figures 3A and 3B.

(A) (B)

Plates 3A and 3B. Senate Building General Passenger Lift

The lift shown in Plates 3A and 3B is a four persons

(630 kg) passenger lift. The lift is provided with an

elevator signage at the top of the door for easy

identification of the lift by users of the building. The sizes

and spaces provided to approach and use the lift on each

floor are over 1800 mm by 1800 mm which is the

minimum requirement in such instance. The lift approach

sizes and spaces on each floor of the building are large

enough to accommodate several people at a time in

conformity with the seventh principle of UD. Though the

height of the lift door is 2000 mm and adequate, the

effective width of the door of 800 mm, falls short of the

minimum acceptable standard of 950 mm. The internal

dimensions of the lift car are 990 mm by 1380 mm, which

also fall short of the minimum standard of 1800 mm by

1800 mm for an accessible lift. This implies that a

wheelchair user will find it difficult to enter and maneuver

within the lift car, contrary to UD requirement. The lift is

also not provided with a handrail within the lift car in line

with UD safety standard. The handrail is usually needed

for users to support themselves when the lift is in motion

to avoid falling. The lift control buttons are positioned at

accessible heights of between 1030 mm and 1200 mm.

These heights are reachable for most people, including

wheelchair users. The lift car is provided with a

full-length mirror at the opposite side of the door. Signage

that indicates when the lift car gets to a particular floor is

provided both inside and outside the lift car. However, it

was observed that there is no audible voice prompt to

complement the signs for the benefit of those with visual

impairment. Nevertheless, the lift is provided with a

speaker for communication in case of emergency. The lift

floor is firm, hard and non-slippery in conformity with



UD requirements. The lift door stays open for

approximately five seconds before closing when called to

action. Its opening and closing speed are steady and

reasonable. The speed of the lift car is also steady and

reasonable. Based on the overall findings on the lift, the

lift is averagely compliant with UD strategies.

Generally, the result on the compliance level of the

vertical movement components of the Senate building

with UD strategies shows that only the main access

staircase within the building complied reasonably with

UD strategies, as most of its specifications conform with

UD standard requirements. But that of the passenger lift

inside the building is considered moderate, as its provision

complied averagely with UD strategies. On the other hand,

the main entrance steps and ramps all recorded a low UD

compliance level to indicate that they are inadequately

provided.

4.2. Centre for Research, Innovation and Discovery

(CUCRID) Building

The CUCRID building comprises of seven floors,

making it the second tallest building on the campus of the

university. The building serves as the centre for all

research, innovation and discovery projects in the

institution. The building was also commissioned by the

Chancellor, Bishop (Dr.) David Oyedepo in June, 2016,

during the convocation week. The building houses start-up

laboratories, research and technology laboratories, the

school of postgraduate studies and several other facilities

meant for promoting research, innovation and discovery in

the university. Just like the Senate building, the vertical

movement components provided for the building are

ramps, steps/staircases and lifts. These components are

examined as follows:

4.2.1. Main Entrance Ramp and Steps

At the main entrance of the CUCRID building, a ramp

and steps are the two vertical movement components

provided for users to access the building from the approach

in line with UD requirement, as shown in Plate 4A and 4B.

(A)

(B)

Plates 4A and 4B. Main Entrance Ramps and stairs

The ramp at the main entrance of the CUCRID building

is located to the right-side of the main entrance steps.

Both the ramp and the steps open into a covered entrance

foyer. The surfaces of the ramp and step treads are

finished with hard and firm granite tiles that are

non-slippery, as shown in Plates 4A and 4B. The height of

the ramp is 900 mm with a length of 9000 mm. The slope

of the ramp is steep. Its gradient is steeper than the 1 to 20

minimum standard specified for an accessible ramp. The

ramp is also not provided with handrails on both sides in

conformity with standard ramp requirement. This makes

the ramp uncomfortable to climb or descend from.

However, the ramp’s effective width of 1600 mm is more

than the minimum standard of 1200 mm for a one-way

accessible ramp. To a large extent, the specifications of

the ramp at the entrance of the CUCRID building fall

short of the requirements for an accessible ramp. This

implies that its compliance level with UD strategies is

low.

However, the UD compliance level of the main

entrance steps is high. This is because, both the risers and

treads of 150 mm high and 450 mm deep respectively, are

within the acceptable dimensions of standard step

requirements stated earlier. The risers are also closed

risers in line with UD requirement. However, the steps

have an effective width of 8450 mm. This necessitates the

provision of at least a handrail due to the large span, as

explained earlier. However, no handrail was provided.

The purpose of the handrail is to enable persons with

mobility difficulty to be able to support themselves when

climbing or descending the steps. Nevertheless, the steps

specifications are to a large extent compliant with UD

strategies, hence adjudged reasonable.

4.2.2. General Access Staircases

The CUCRID building is provided with a total of four

staircases out of which two are located in the main entrance

hall behind the reception desk, serve as the general access

staircases. The other two are situated at the far right and far

left inside the building and serve as fire escapes and service


staircases, as well as compliment the two general access

staircases. Based on the scope of the study, only the general

access staircases were examined. The two staircases are

identical. They are winding in nature, as shown in Plates

5A and 5B.

(A)

(B)

Plates 5A and 5B. CUCRID General Access Staircases

The general access staircases in the CUCRID building

are steel framed structures with their treads and

intermediate landing platforms anchored to the steel frames,

as shown in Plates 5A and 5B. The dimensions of the treads

are 400 mm and consistent in conformity with UD

requirements. The size of the treads also falls within the

acceptable range of between 300 mm and 450 mm for

accessible designs. The surface of the treads was finished

with polished granite that is hard, firm and non-slippery in

line with UD requirement. However, the risers are not

consistent contrary to UD requirement. They are largely

between 150 mm and 170 mm in height. In some cases,

they are as low as 70 mm and as high as 190 mm, which are

outside the acceptable height range of between 150 mm

and 180 mm for steps. The risers are also open risers which

are considered not safe as a user’s foot may mistakenly slip

through them. This makes the stairs not completely safe to

climb or descend from as anyone may miss a step and fall

on them. The effective width of the stairs is 1470 mm,

while that of the landings is 2000 mm. These dimensions

are adequate as they are more than the acceptable minimum

limit of 1200 mm recommended for passage ways. The

staircases flights are made up of an average of 12 risers.

This falls within the maximum allowable limit of 15 steps

per flight. The staircases are also provided with round

stainless-steel handrails of 50 mm diameter on either side

of the stairs. The handrails height range are largely between

1000 mm and 1100 mm. These specifications of the

handrails are fairly consistent with standard handrail

requirements. However, few areas of the handrails have

heights lower than the acceptable limit of 900 mm. In a

case, it is as low as 700 mm which is not safe. Also, a lower

handrail was not provided for in line with UD requirement.

Nevertheless, based on the findings on the two general

access staircases in the CUCRID building, their overall

compliance level with UD strategies is average.

4.2.3. Lifts

(A) (B)

Plates 6A and 6B. CUCRID Building General Passenger Lifts

The general access lifts in the CUCRID building are

situated between the general access staircases within the

main entrance hall. Though four lift shafts are provided,

only two of them are equipped with lift cars used for

vertical movement of users within the building, as shown

in Plates 6A and 6B.

Each of the two passenger lifts shown in Plates 6A and

6B is a fifteen persons (1000 kg) passenger lift. An elevator

signage was provided at the top of the lift doors for users to

be able to easily identify the lift. The sizes and spaces for

approach and use of the lift provided on each floor is

adequate, as their dimensions are over the 1800 mm by

1800 mm minimum requirement specified for accessible



lifts. The sizes of the spaces are wide enough to

accommodate several persons at a time in line with the

seventh principle of UD. The height of the lift door is 2100

mm and within the acceptable limit of 2000 mm. However,

the effective width of the lifts doors is 800 mm. This falls

short of the acceptable limit of 950 mm. The effective

lengths and widths of the lift cars is 1700 mm and 1200 mm

respectively. These dimensions also fall short of the

minimum size of 1800 mm by 1800 mm specified for

accessible lifts. Wheelchair users will also most likely find

it challenging when entering, as well as maneuvering

within the lift cars. In addition, the lift cars are built with

transparent glass panels which might not be suitable for

people who are scared of heights. But standard handrails of

950 mm are provided within the lift cars in conformity with

UD safety standard. The handrails are used by users to

support themselves when the lift is in motion. Most of the

control buttons of the lift are positioned at accessible

heights of between 950 mm and 1200 mm. Just two of the

buttons whose height are 1300 mm and 1600 mm are

positioned outside the accessible height range. Signage that

indicates when the lift car gets to a particular floor was

provided inside, as well as outside the lift car. Nonetheless,

it was also observed that no audible voice prompt was

made available to complement the signs for the benefit of

people with visual impairment. But the lift has a speaker in

it for communication in case of emergency. The floors of

the lift cars are firm, hard and non-slippery in line with UD

requirements. The lift doors stay open for approximately

five seconds before being closed. The doors opening and

closing speed, as well as the speed of the lift cars, are

steady and reasonable. In view of the general findings on

the lifts, their compliance level with UD strategies is

average.

In general, the findings on the compliance level of the

vertical movement components of the CUCRID building

with UD strategies indicates that only the main entrance

steps complied reasonably with UD strategies, as majority

of its provisions are in line with UD requirements. The

main entrance ramps recorded a low UD compliance level

as most of its provisions do not conform with UD

requirements. But, the compliance level of the two

passenger lifts and the two general access staircases within

the building with UD strategies, is moderate. This is

because their provisions are averagely compliant with their

respective UD strategies.

4.3. Discussion of Findings

The findings from the analysis of the field data gathered

on the vertical movement components of the Senate and

CUCRID buildings in Covenant University presented in

Sections 4.1 and 4.2, show that both high-rise buildings are

provided with at least a ramp and steps at their main

entrances to enable users gain access into the buildings.

Similarly, each of the building is provided with at least a

general access staircase and a lift within the building to

enable users transport themselves from one floor to the

other. This indicates that conscious attempts were made at

the main entrances and within both buildings to provide for

the vertical accessibility needs of all potential users,

including the physically challenged, in conformity with

UD requirements.

However, a detailed examination and analysis of the

vertical movement components show that majority of their

provisions do not conform with UD strategies. Only the

steps at the main entrance of the CUCRID building and the

general access staircase inside the Senate building,

recorded high UD compliance levels, as most of their

provisions conformed with UD requirements. Hence, only

these two vertical movement features of the high-rise

buildings are adjudged to be reasonably compliant with UD

requirements. The provisions of the lifts in both buildings

and that of the general access staircases within the

CUCRID buildings are adjudged moderately compliant

with UD requirements. This is because their provisions

were found to averagely comply with UD strategies.

However, the ramps at the main entrances of both buildings,

as well as the steps at the approach of the Senate building,

all recorded a low UD compliant level, as most of their

provisions were found not to comply with UD strategies.

It is apparent from the result that the provisions of the

vertical accessibility components in the high-rise buildings

are inadequate. The most affected are features commonly

useful for the physically challenged. For instance, all the

ramps at the main entrances of the buildings recorded low

UD compliance levels, while the provisions of the lifts in

both buildings are barely averagely compliant with UD

requirements. Only one of the main entrance flights of

steps and a general access staircase, which are usually

accessibility features provided for the benefit of

able-bodied persons within one of the buildings, recorded

high UD compliant ratings. This goes to show that the

physically challenged, particularly those who use mobility

aid such as wheelchair users, as well as the aged and

workers pulling or pushing trolleys, will most likely find it

challenging using the vertical movement features

components situated in the high-rise buildings.

Generally, the findings of the study corroborate several

other previous studies that found that people living with

one form of disability or another are often not adequately

provided for in public buildings in terms of their

accessibility and usability needs, compared to provisions

made for able-bodied persons [9,29,31,14,15,3,17]. The

result on ramps specifically tallied with the results of

Sholanke, Adeboye & Alagbe; Sholanke, Adeboye,

Oluwatayo & Alagbe; Yusita, Yong & Thamrin [31,3,17].

The said authors found that ramps provided at the main

entrances of public buildings they investigated (academic

buildings in universities in Nigeria and shopping malls in

Surabaya), are most likely to hinder accessibility for the

physically challenged users of the buildings as a result of


various inadequacies identified that contravene UD

requirement. Few of such inadequacies are lack of

handrails attached to the ramps and steeped ramp gradients.

The result also conformed with the findings of Sholanke

[30] that discovered that academic buildings in selected

universities in Nigeria are largely inadequately equipped

with vertical movement features suitable for the use of the

physically challenged, despite most of the buildings being

storey buildings comprising more than two floors.

In general, the vertical accessibility components of

high-rise buildings in Covenant University are not

satisfactorily compliant with UD strategies. The buildings

are not sufficiently equipped with enough vertical

movement provisions that can guarantee the promotion of

social inclusivity in educational environments in the study

area. While able-bodied persons might not find it difficult

to independently gain access into the building from their

main entrances, as well as travel up and down between

floors inside the buildings, the physically challenged,

especially mobility aid users, will most likely find it

challenging to do same.

5. Conclusions

The study was conducted to examine the compliance

level of vertical movement components of high-rise

buildings with universal design strategies in Covenant

University, Ota in Nigeria, in order to identify areas for

further improvements, towards contributing to ways of

promoting social inclusion in educational environments.

The Senate building and the Centre for Research,

Innovation and Discovery building are the two buildings

that fall under the category of high-rise buildings in the

university campus. A summary of areas found not to

comply with universal design requirements, hence call for

improvements in the buildings include: steep ramp

gradients, narrow ramp widths, lack of handrails to ramps,

inadequate and inconsistent step risers and treads,

inadequate staircases handrails and lifts specifications. Lift

provisions that fall short of universal design minimum

requirements are their effective door widths, effective car

sizes, heights of some lift control button and lack of

support handrails within a lift car. In general, the findings

show that adequate vertical movement provisions are not

made in the high-rise buildings. Accessibility components

usually needed by people with mobility impairment are the

most affected. The general implication of the results is that

the buildings lack enough vertical movement components

for promoting social inclusion in the university campus.

The key contribution to knowledge of the study is the

provision of empirical data on the compliance level of

vertical accessibility components of high-rise buildings

with UD strategies in the study area. The study also

revealed specific areas of the vertical movement

components in the said high-rise buildings that

contravened UD requirements and require attention. The

paper stands to increase awareness on the importance of

conforming with UD strategies in the development of

accessible academic environments. It further draws

attention to the inadequate and lack of appropriate

provisions for the handicapped members of the society in

the design and development of public environments. In

general, the paper has established a new empirical based

study from where further studies can be generated.

Based on the findings of the study, the following

recommendations are made: where possible, the buildings

should be retrofitted with necessary accessibility

provisions where they are lacking or inappropriately

provided; measures should be put in place by the university

management to ensure that further high-rise buildings in

the university are designed and developed to comply with

universal design strategies generally, especially with

regards to vertical movement provisions; there is also a

need to review building development guidelines in the

study area to ensure that they are capable of promoting

social inclusion in the development of the

built-environment; building professionals, especially

architects should always take care to make adequate

provisions for the accessibility needs of everyone,

including people with disabilities, in the development of

high-rise buildings. Conscious efforts should be made to

ensure easy vertical movement for all potential users in

such buildings.

Lastly, the authors recognise that, because the study is a

case study limited to Covenant University high-rise

buildings, its findings cannot be generalised beyond the

university setting. Consequently, similar studies should be

conducted in other universities in Nigeria and other

countries around the globe to help provide a broader insight

into the subject matter. Such studies are necessary as they

are likely to provide more insight into possible areas that

require improvements in the development of high-rise

buildings in academic settings, towards promoting social

inclusion in the development of inclusive learning

environments. For the same reason, similar studies could

be extended outside the university environment to include

office buildings, hotels and residential apartment blocks.

An objective approach was adopted to conduct this study.

Further studies can employ subjective means that rely on

users’ perception to evaluate the effectiveness of vertical

movement components in high-rise in meeting users’

needs.

Acknowledgements

The authors are appreciative of Covenant University

management for the support, necessary resources and

conducive atmosphere provided to carry out this study.

The peer reviewers whose suggestions provided the

authors the opportunity to improve the quality of the



earlier manuscript are acknowledged and appreciated. The

authors are also appreciative of all authors whose research

materials were consulted in the course of gathering

background information for the paper. All of such

scholarly materials were duly cited in the work and

referenced in the following section.

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Civil Engineering and Architecture 8(5): 750-759, 2020 http://www.hrpub.org DOI: 10.13189/cea.2020.080502

The Occupational Health and Safety Effect on Road Construction Worker Performance

Fourry Handoko1,*, Maranatha Wijayaningtyas2, Imam H. A. Kusuma2, Sutanto Hidayat2, A. Ismail3, Z. Abdullah4

1Industrial Engineering, National Institute of Technology Malang, Indonesia 2Civil Engineering, National Institute of Technology Malang, Indonesia

3Department of Real Estate, Faculty of Build Environment, Universiti Teknologi Malaysia, Malaysia 4Faculty of Engineering, Universiti Teknikal Malaysia Melaka, Malaysia

Received June 17, 2020; Revised August 1, 2020; Accepted August 25, 2020

Cite This Paper in the following Citation Styles (a): [1] Fourry Handoko, Maranatha Wijayaningtyas, Imam H. A. Kusuma, Sutanto Hidayat, A. Ismail, Z. Abdullah , "The Occupational Health and Safety Effect on Road Construction Worker Performance," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 750 - 759, 2020. DOI: 10.13189/cea.2020.080502.

(b): Fourry Handoko, Maranatha Wijayaningtyas, Imam H. A. Kusuma, Sutanto Hidayat, A. Ismail, Z. Abdullah (2020). The Occupational Health and Safety Effect on Road Construction Worker Performance. Civil Engineering and Architecture, 8(5), 750 - 759. DOI: 10.13189/cea.2020.080502.


Abstract This study was designed to analyze the factors of Occupational Health and Safety (OHS) implementation affecting the performance of road construction workers. The research employed a quantitative survey method by self-distributing questionnaires using simple random sampling to 50 road construction workers on a road-widening project, with a 99% response rate. The analysis based on the results of the questionnaire data through the validity test, reliability, and the multiple regressions testing: f-test and t-test of each statement item. Regarding the descriptive analysis test results, the most dominant among several elements of Work Safety variable statement was the appropriate use of work equipment, which was 81%. In contrast, the practical result of the Occupational Health variable was the first aid kits provided by companies, which was 82%. For the Worker Performance variable, the dominant result was the workers' attitude to conform to the rules leading to achieving work targets, which was 88%. Furthermore, according to the results of multiple regressions testing, it can be concluded that the implementation of occupational safety and health had a positive effect on employee performance. The findings show that the application of OHS in construction projects affects the performance of workers which ultimately also determines the achievement of the company's work targets.

Keywords First Aid Kits, Personal Protective Equipment (PPE), Road Projects, Worker Attitudes, Work Targets

1. IntroductionThe technology transfer program objectives are to

enhance the capacity of human resource development, especially in technology [1,2]. Besides, technology transfer is recognized as a means to advance technology capability and is inseparable from the implementation of infrastructure and property construction [3.4,5,6]. The construction sector has become one of the crucial areas of the national economy in developed and developing countries [7,8,9]. Human resources have an essential role in the success and need special attention from the company [10,11]. The fact that humans are a significant asset in an organization or company must receive serious consideration, and they must be managed as best as they can. Concerning human resources, the management must manage resources systematically, efficiently, and with careful planning [12].

Worker performance defines the quality and quantity of work achieved by employees in performing their duties in


conformity with the responsibilities given to them [10]. Additionally, in the performance of human resources, the occupational health and safety system must be of concern. In Indonesia, the number of work accidents is alarming. According to research conducted by the International Labor Organization (ILO), Indonesia ranks 52 out of 53 countries with poor OHS management, even though the costs incurred by the company will be substantial should there be an accident at work [13].

According to data from the International Labor Organization (ILO) in 2010, there were more than 2 million people died due to accidents and occupational diseases each year. Approximately 160 million people suffer from occupational diseases and 270 million cases of work accidents annually throughout the world [14]. Those data indicate that occupational health and safety in Indonesia is low as they have not received attention and become a part of the culture in Indonesian society [15].

As stated by the construction management agency staff of the Ministry of Public Works in the construction management sector, the implementation of Occupational Health and Safety (OHS) programs in each development project is not good. The Ministry of Public Works has also required every contractor to carry out OHS. A variety of OHS programs implemented in the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency, include providing adequate Personal Protective Equipment, health facilities, and social security for workers. Thus, this study focused on the construction of the shaft and monument construction into the district government office.

This study will study the case in the construction mentioned above project only in Sumenep City District, Sumenep Regency, Indonesia, this study is only specific to one development site and will not be widen to other aspects. In this case, the researchers sought to confirm the implementation of OHS in the project. From the description, the identification of the problems are: 1. Lack of sensitivity from the company regarding the

importance of workers occupational health and safety (OHS) on a project under the company auspices.

2. Lack of attention from the company to provide better services and equipment related to work safety for its workforce as an essential factor of all project objectives.

3. Lack of understanding by workers of the risks regarding occupational health and safety (OHS).

However, there is a gap from previous research on the effect of the implementation of OHS by construction workers on performance improvement. According to Busyairi [16], it showed that the variables of work safety (work environment, work safety equipment, work methods) and occupational health variables (health checks, rest hours, ergonomics) had positive and significant contributions on worker productivity in manufacturing companies.

Nonetheless, the results of Firmanzah's research [17] in the state electricity company showed that work safety variables had a negative and significant effect on employee performance. Therefore, the inequality of the results provides an opportunity to examine the extent of the influence of OHS on the performance of workers in cases in construction projects, especially on road construction projects.

Accordingly, the problem formulation is as follow: 1. What are the factors of implementing Occupational

Health and Safety (OHS) that can affect the performance of workers on the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency?

2. How is the performance of workers affected by the implementation of Occupational Health and Safety (OHS) on the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency?

This study can enrich the researchers' knowledge about the effect of Occupational Health and Safety (OHS) programs implementation and work motivation on worker productivity. It can also be used as further research material for other researchers interested in this field and to learn how much the implementation of Occupational Health and Safety (OHS) programs and work motivation affect employee productivity. Thereby, companies can find out the extent of the program that has been applied and how important it is to carry out the Occupational Health and Safety (OHS) program on employee performance.


2.1. Occupational Health and Safety (OHS)

Many industries put OHS in a prioritised need. Without its application in the work environment, there will get a high chance of work accidents. According to occupational safety research by Firmanzah et al. [17], the critical factors of applying OHS are:

1. Humanity Employees are people who should not be seen merely as

a means of production; they are individuals serving as the company's assets. Thus, every human being needs to be protected from all possible threats and dangers.

2. Government Regulations A company, regardless of the type of business, aims to

create a product that can be used by the community; its existence is related to the community, and so it is regulated through various regulatory mechanisms.

752 The Occupational Health and Safety Effect on Road Construction Worker Performance

3. Economy Economic factors are also the driving force for the

implementation of OHS maintenance in a company. Understandably, a company's operations will always follow economy consideration, such as seeking profit. Maintaining OHS means the company has to pay more. However, the costs incurred will be even higher if a work accident occurs. OHS maintenance intends to prevent work accidents.

Swasto [18] asserted work safety involves the whole process of protecting workers against the possibility of hazards arising in the work environment. There are two attempts to provide work safety for employees, according to Soeprihatno [19], they are: 1. Preventive efforts such as controlling or inhibiting the

source of danger in the workplace so that it can be reduced or not cause risk to employees.

2. Repressive efforts such as dealing with incidents or accidents caused by sources of danger in the workplace.

In addition to preventing employees from accidents, the company also needs to maintain employees' health which includes physical and mental health. Employees can be affected due to illness, stress, or accidents. According to Manulang [20] and Simamora [21], there are three indicators of Occupational Health: 1. Medical work environment 2. Workforce health environment 3. Maintenance of workforce health

2.2. Occupational Health and Safety (OHS) and Worker Performance

Simamora [21] says that performance refers to the degree of achievement of tasks, where it can form an employee's job. Performance reflects how well employees meet the requirements of a job. Mangkunegara [22] argues that human resource performance is a term derived from the word Job Performance or Actual Performance (work performance or actual achievement achieved by someone). Therefore, it concludes that the performance of human resources is work output (quality) both in quality and quantity made per unit period in carrying out their work following the responsibilities given to them.

Several studies in Indonesia show that there is an influence between OHS and the performance of workers in several different types of work such as workers in the manufacturing industry, electricity companies, and general services [16,17,23,24,25]. However, the results of the previous studies were different, some showing that health and safety had a positive effect, but others showed a negative influence between OHS and employee performance. Thus, this study using the same variables as some of the previous reviews will test the effect of OHS on the performance of workers in construction projects. The hypothesis formed is: 1. H1 - work safety positively influences worker

performance 2. H2 - occupational health positively affects worker

performance The variables to be used are as shown in Table 1, with

the research conceptual framework shown in Figure 1.

Table 1. Research Variables

No. Variables and Indicators Sources

1 Work Safety

Guarantee of Occupational Safety and Health Occupational Safety and Health Training Physical work environment Psychological, social environment Work safety equipment Types of work tools Equipment condition Safety devices

[14] [15] [21] [22] [23]

2 Occupational Health

Personal Protective Equipment Workload Work environment and health insurance Working conditions Workforce health facilities Maintenance of workforce health Medical examination Rest time Ergonomics Workplace cleanliness Maintenance of work tools Enough lighting when overtime Sound noise Air temperature

[14] [15] [21] [22] [23]

3 Worker Performance

Working Hours Quantity and quality of work Timeliness Work equipment Job opportunities Knowledge Skills

[14] [15] [21] [22] [23]


Figure 1. Research conceptual framework

3. Materials and Methods This section discusses the research methods used to

analyse the Occupational Health and Safety (OHS) implementation factors affecting the performance of workers on the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency. The research strategy determines to obtain the data needed in advance. The following aspects affecting the types of procedures are used in this study: a. The type of statement used b. Control of the events understudy c. Focus on current events

3.1. Research Methods

The method used in this research was descriptive research, and the type was quantitative research. According to Sugiyono [26], descriptive study is the research conducted to determine the value of independent variables, either one or more variables (independent) without making comparisons or connecting with other variables. Moreover, it is a quantitative research; according to Sugiyono [26], it is the research conducted by obtaining data in the form of numbers or compiled qualitative data.

3.2. Research Design

Research design is a framework or plan for conducting studies that will be used as a guide in collecting and analysing data. Based on the problem formulation and research objectives, it can be concluded that the design used in this study uses descriptive and verification analysis methods. According to Sugiyono [26] that the descriptive analysis method is a statistic used to analyse data in a way, describe the data that have been collected as they are. While verification applied to test hypotheses using statistical test equipment, this study uses multiple linear regression analysis test equipment.

3.3. Data Collection Technique

According to Sugiyono [26], data collection techniques

are the most strategic step in research because the primary purpose of the research is to collect data. In this study, researchers used two types of data: primary and secondary; the primary data were used to find out the effect of the implementation of Occupational Health and Safety (OHS) on employee performance and the secondary data were to support research data presentation. The data collection processes were as follow:

1. Primary Data

Primary data are a source of data obtained directly from the source (not through intermediary media). It can be in the form of individual or group subject opinions, observations of objects (physical), events or activities, and test results. The method used to obtain primary data is the survey method: The survey method is a central data collection method

using a written statement. This method requires a contact or relationship

between the researcher and the subject (respondent) of the study to obtain the necessary data.

The data obtained are mostly descriptive, but data collection design is to solve cause and effect or express ideas.

They are generally used to collect the same data from many subjects.

The techniques used are distributing questionnaires and conducting interviews.

2. Secondary Data

Secondary data are a source of research data obtained indirectly through intermediary media (collected and recorded by other parties). Secondary data are generally in the form of evidence, notes or historical reports that have been arranged in archives (documentary data) that are published and not published.

3.4. Population and Sample

The population is a generalisation area consisting of objects or subjects with specific qualities and characteristics determined by researchers to study and draw a conclusion [11]. The population in this study was all 50 workers on the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency.

The sampling method, according to Sugiyono [26], is to determine the sample to be used in research. The non-probability sampling employ in this study, which was saturated sampling. Then, the saturated sampling technique is when all members of the population are used as samples. This method is applied if the population is relatively small or less than 30 people. A saturated sample is also called a census, in which all members of the population as respondents. The researchers use this type of sampling since there were 50 people in the population.


The researchers used a percentage error of 1% = 0.01 for a small population, then calculated the sample size using the Slovin technique; according to Sugiyono [26], it is as follows :

𝑛 = 𝑁1+𝑁𝑒²

………. (1)

In which: n = sample size N = population size i.e. project workers e = per cent leeway for inaccuracy due to error taking. Then the number of samples to be examined is:

n = 501+50(0.01)²

n = 49.9 = 50 people

3.5. Data Analysis Technique

In this study, the researchers used a descriptive and associative analysis approach to determine the causal relationship with the survey approach considering the variables to be processed and the purpose to present a structured, factual, and accurate illustration of the facts and the relationships between the variables studied.

The data analysis is an activity carried out after the data from all respondents were collected [26]. It involves grouping data based on variables and types of respondents, stimulating data based on variables from all respondents, presenting data from each variable studied, doing calculations to answer the problem formulation, and doing calculations to test proposed hypotheses.

The instruments used in the research are then tested for validity and reliability. A validity test confirms whether the instrument used to obtain data in the study can be used or not, while the reliability test confirms whether the instrument will produce the same data in several times testing or to measure the same object. The validity test of the instrument in this study was conducted to find out whether the measuring instrument, which was a questionnaire, could carry out its functions. As explained in the research method, a statistical approach was used through the correlation coefficient of the item's statement score with the total item's statement score; if the correlation coefficient is greater or equal to 0.30, the statement is declared valid.

A reliability test applied to find out whether the measuring instrument designed in the form of a questionnaire can rely upon; a measuring instrument is reliable if it will give relatively the same results (not much different) when used repeatedly. A statistical approach is used to see whether a measure is reliable or not; it is done through the reliability coefficient. If the reliability coefficient is greater than 0.60, the whole statement is declared to be reliable.

After the data collected from the field, then a descriptive analysis is performed by displaying the percentage of the average value of each indicator. This method is used to describe the implementation of occupational health and

safety at the company and the level of performance of workers after the implementation of the Occupational Health and Safety (OHS) system.

The quantitative approach used in this research was the multiple linear regression analyses to test the hypotheses. Multiple linear regression analysis is applied if there are several independent variables of at least two or more. The multiple linear regression analysis aims to examine the effect of the independent variables on the dependent variables, either partially or collectively. It is also useful to find out which independent variable most influences the dependent variable by using or calculating multiple linear regression equations.

1. F-test F-Test Analysis is used to find out the positive, negative,

and significant relationship between the variables l-variable Occupational Safety (X1) and Occupational Health (X2) simultaneously with the variable of Worker Performance (Y).

2. T-test T-Test analysis is used to test the regression coefficient

partially and determine whether the effect of the variables Safety (X1) and Occupational Health (X2) on the variable Worker Performance (Y) is significant or not.

3. Linear Regression Equations According to Sugiyono [26], multiple linear regression

analysis is intended to predict the condition (the ups and downs) of the dependent variable (criterion). However, if two or more independent variables as a predictor factor are manipulated (raised the value down); so, multiple regression analysis will be conducted if the number of independent variables is at least two.

3.6. Research Instruments

In this study, researchers used the Likert scale 5 to measure the level of performance of workers; some examples of the Likert scale in this study are presented in Table 2.

Table 2. Likert scale

Likert Scale Score Strongly Disagree (SD) 1

Disagree (D) 2 Neutral (N) 3 Agree (A) 4

Strongly Agree (SA) 5

According to Sugiyono [26], the notion of a research variable is an attribute, trait, or value of people, objects or activities having individual variations determined by researchers to be studied and conclusions could be drawn. In this study, there are three variables and indicators, as shown in Table 3: Work Safety required in a job to guarantee the welfare

of working life (X1)


Occupational Health means a prosperous condition of the body, soul and social, allowing a person to live productively, socially, and economically (X2).

Worker's performance is the result or level of an optimal person in carrying out the task or work (Y).

Table 3. Research Variables Indicators

No Work Safety (X1)

Occupational Health (X2)

Worker Performance (Y)

1 Work protective equipment

Medical examination Ability

2 A safe workplace Noise Effectiveness

and efficiency

3 Use of work equipment Time off Attitude

4 Working

equipment condition

Enough lighting when overtime Situation

5 Work equipment placement

Workplace Cleanliness Skills

4. Results and Discussion

4.1. Validity Test

The validity test was conducted to statement items related to all indicators after surveying by distributing questionnaires to 50 respondents in the construction project of the shaft road and entry monument of the integrated district government office in Sumenep City District, Sumenep Regency. Then, the data containing the score of the statement items in the questionnaire were included in the table. Furthermore, the correlation value of each item to the total score was calculated. The results of the validity test, as shown in Table 4.

Table 4. Test Validity of Research Indicators

No Indicator The correlation coefficient (r-count)

r-table value (α=1%) Result

1 X1.1 0.822 0.463 Valid 2 X1.2 0.709 0.463 Valid 3 X1.3 0.800 0.463 Valid 4 X1.4 0.752 0.463 Valid 5 X1.5 0.731 0.463 Valid 6 X1.6 0.614 0.463 Valid 7 X2.1 0.642 0.463 Valid 8 X2.2 0.701 0.463 Valid 9 X2.3 0.725 0.463 Valid 10 X2.4 0.774 0.463 Valid 11 X2.5 0.683 0.463 Valid 12 X2.6 0.641 0.463 Valid 13 X2.7 0.698 0.463 Valid 14 Y.1 0.785 0.463 Valid 15 Y.2 0.828 0.463 Valid 16 Y.3 0.861 0.463 Valid 17 Y.4 0.790 0.463 Valid 18 Y.5 0.752 0.463 Valid 19 Y.6 0.748 0.463 Valid

4.2. Reliability Test

The reliability test technique used the alpha reliability coefficient. The decision-making criterion was that if the value of the alpha reliability coefficient is greater than 0.6, the variable is reliable. The test results are shown in Table 5.

Table 5. Reliability Test Research Indicators

No Variable Alpha Reliability Coefficient Result

1 Work Safety (X1) 0.832 Reliable

2 Occupational Health (X2) 0.819 Reliable

3 Worker Performance (Y) 0.881 Reliable

4.3. Descriptive Analysis

Descriptive analysis is conducted to find out about the implementation of occupational health and safety affecting the performance of workers, a percentage analysis was performed to calculate the percentage of the average score of each statement variable's item to describe the level of meeting a predetermined criterion. The results of the analysis are shown in Table 6.

Table 6. Descriptive Analysis Results

No Indicator Total Mean Percentage

1 X1.1 112 3.73 74%

2 X1.2 119 3.97 79%

3 X1.3 110 3.67 73%

4 X1.4 122 4.07 81%

5 X1.5 115 3.83 76%

6 X1.6 112 3.73 74%

7 X2.1 124 4.13 82%

8 X2.2 114 3.80 76%

9 X2.3 115 3.83 77%

10 X2.4 111 3.70 74%

11 X2.5 112 3.73 75%

12 X2.6 110 3.67 73%

13 X2.7 122 4.07 81%

14 Y.1 127 4.37 84%

15 Y.2 130 4.33 86%

16 Y.3 133 4.43 88%

17 Y.4 121 4.03 80%

18 Y.5 120 4.00 80%

19 Y.6 119 3.97 79%

The indicator with the highest Mean on the Work Safety (X1) is a statement that workers have properly used work equipment while doing work. The lowest mean value was that the company always controls the work location regularly.


The indicator with the highest Mean in the Occupational Health (X2) is the statement that the company has provided first aid kits, while the lowest mean value is that workers feel comfortable when doing overtime work with adequate lighting at the project site.

The indicator with the highest Mean on Worker Performance (Y) is a statement that workers always maintain their attitudes and conform to the rules that have been set so that work targets are achieved. At the same time, the lowest mean value is the company provides workload based on the workers' skills.

4.4. Multiple Linear Regression

Linear regression analysis of research variables is a statistical calculation approach done by tabulating and calculating research data so that it produces output to conclude. The properties of the data can determine the calculation of the value of central tendency (a measure of primary value), for example, the mean and median values. The path diagram of the modelling results is shown in Figure 2. Based on the results of the F-Test and T-Test, the regression analysis results are obtained and shown in Table 7.

Figure 2. Path Diagram Analysis Result


Table 7. Multiple Linear Regression Analysis Results

Variable B 𝑡𝑐𝑜𝑢𝑛𝑡 Sig. Work safety (X1)

Occupational health (X2) Worker performance (Y)

0.496 0.408

2.849 2.696

0.008 0.012

The details are as follows: Constanta : 2.743 R : 0.743 R. Square : 0.552 F-count : 16.601 F-table : 3.910 Sig F : 0.000 T-table : 0.701 Multiple Linear Regression Equations

𝑌 = 2.743 + 0,496𝑋1 + 0,408𝑋2. (2)

The result of the regression equation has the following meanings:

A constant of 2.743 shows results that affect Worker Performance (Y) of external variables are not included in this study, respondents' perceptions before the effect of occupational health and safety.

The regression coefficient on the work safety variable (X1) of 0.496 indicates that the implementation of work safety programs can affect improving worker performance (Y), which has positive coefficient values. Thus, it can be interpreted that the work safety programs appropriately implemented can be used as a driving force to increase employee performance (Y) on other variables constant.

The regression coefficient on the occupational health variable (X2) of 0.408 shows that the company's efforts to maintain occupational health through health programs for workers and work environment health have an impact on improving employee performance (Y), which have the coefficient values not negative. This means that occupational health programs (X2) can improve worker performance (Y) with constant variables. Thus, all research hypotheses can be accepted.

4.5. Discussion

However, this research finding support Busyairi's study [16], who researched the implementation of OHS in manufacturing companies, shows the same results that OHS has a positive effect on improving employee performance. Nonetheless, these results, contrary to Firmanzah's research [17] in the state electricity company showed that work safety variables had a negative and significant effect on employee performance. According to the respondent's answer, the performance of workers affected by the implementation of Occupational Health and Safety (OHS) has a positive effect on work because the work is in an open location and a lot of manual work is conducted by workers who need protection. For example, the safety helmets are worn on the head to protect the worker from the scorching heat of the sun and to focus

more on open work; if workers do not wear safety helmets, the workers are troubled by the heat of the sun on free labour. Rubber boots are dressed in a mixing-work and manual excavating so that the workers are protected from foot injuries. According to the respondent, at around 25% of the mixing-work progress, workers are injured when using shoes.

5. Conclusions To conclude, the implementation of Occupational

Health and Safety (OHS) factors affecting the performance of workers are as follows: 1. Work Safety Factor (X1) with the highest result of

X1.4 = 4.07, with a percentage of 81% (Very Good); Occupational Health factor (X2) with the highest result of X2.1 = 4.13, with a percentage of 82% (Very Good); Worker Performance factor (Y) with the highest result of Y.3 = 4.43, with a percentage of 88% (Very Good).

2. From the results of interview responses, the Occupational Health and Safety (OHS) has a positive effect on the performance of workers since this job is in an open location and involves a lot of manual works.

The contributions of this research are: 1. Theoretically, it would increase knowledge in the

field of OHS regarding the effect of the implementation of occupational safety and health (OHS) programs and work motivation on worker productivity. This study is used as further research material for other researchers interested in this field, and supports previous research that there is an effect of the implementation of occupational safety and health (OHS) programs and work motivation on worker productivity.

2. Practically, for companies engaged in fields other than construction services, they can find out the extent of the programs that have been carried out in construction projects and know the importance of the implementation of the Occupational Safety and Health (OHS) program to support the improvement of worker performance.

Accordingly, the following limitations and future directions for the next research are: Because the main limitation of this study is the small

sample size, further research expects to collect more samples of respondents from several types and project locations.

The application of different analytical methods or research variables would increase the performance of workers. It is also expected that further research will be expanded that there will be more broad conclusions and benefits of study on occupational


safety and health, given the occupational risks in a company.

Project implementers expect to carry out Occupational Health and Safety (OHS) conforming to applicable regulations and to complete the required personal protective equipment (PPE) to improve the performance of construction workers further.

Acknowledgements We are very grateful to the construction company for

their appropriate and constructive suggestions to support the data of this study.

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A Structural Format to Facilitate User Input for the Co-design of a Cardiac Health Unit

Tanut Waroonkun

Faculty of Architecture, Chiang Mai University, Thailand


Cite This Paper in the following Citation Styles (a): [1] Tanut Waroonkun , "A Structural Format to Facilitate User Input for the Co-design of a Cardiac Health Unit," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 760 - 770, 2020. DOI: 10.13189/cea.2020.080503.

(b): Tanut Waroonkun (2020). A Structural Format to Facilitate User Input for the Co-design of a Cardiac Health Unit. Civil Engineering and Architecture, 8(5), 760 - 770. DOI: 10.13189/cea.2020.080503.


Abstract Experience-based co-design and post occupancy evaluation are two mechanisms adopted for future planning and design of built spaces. They share a common strategy in that they both require input from a prospective, or current, built environment user. In the case of healthcare spaces, these users include doctors, nurses, patients and family. However, obtaining relevant and useful information from these sources is problematic. The users lack any specific conceptual knowledge and skills required in the design process. Several authors have addressed this issue by asking the user to comment on specific healthcare environment variables. These variables are the results of prior evidence-based research. Based on the work of Van der Voort and Van Wegen (2005) the author has developed a survey questionnaire and user input procedure Waroonkun (2019) that addresses the functional elements of a healthcare, built environment (in this case, a cardiac health unit). The strength and impact of this method was its ability to tap into a broad functional view of the users’ experience of a built environment. The results of the present study indicate using a POE based, structured assessment strategy provided a solid guideline for determining a wide range of design issues from a user perspective.

Keywords Experience-based Codesign (EBCD), Post Occupancy Evaluation (POE), Cardiac Health Unit (CHU)

1. IntroductionThe Maharaj Nakorn Chiang Mai Hospital is a large

public hospital in regional Thailand. The hospital has expanded substantially over its history. Part of this development was the establishment of a Cardiac Health Unit some twenty years ago. The Cardiac Health Unit (CHU) was proposed and built during the period when hospital management adopted an “incremental” approach to development: no forward overall strategy plan [15]. The physical space initially allocated to the cardiac unit was a specific square-footage. Facilities required for the center had to be designed to fit the allocated space. There was no consideration given to sustainability/flexibility, and definitely limited interest in a patient-centered approach to design.

Patients attend the Cardiac Health Unit as outpatients. They are either making an initial enquiry (after referral by a physician) regarding concerns of more serious cardiac problems, or they are attending for follow-up after heart related diagnoses that require monitoring, or they have recently undergone heart surgery and/or pacemaker implant. The limitations of the facility have become obvious. The situation has been exacerbated by the increasing number of patients: a result of increased longevity of the population and the increase in incidence of cardiac problems in the community.

The author was invited to investigate any built-space design issues effecting the efficient functioning of the current CHU. The rationale was to provide comment on any structural changes required, or alternatively, to provide advice on the construction of a new site. To this end, the author has chosen to use an experience-based co-design (EBCD) model. EBCD is a participatory process wherein stakeholders of a service or product have input to its final


design. Considerable research is now available regarding the use of EBCD in the development of healthcare services [3]. There is, however, limited research discussing the role of EBCD in the design of physical hospital spaces.

Based on a model developed by Bate and Robert (2007) researchers (healthcare services) have sought stakeholders’ input using surveys, interviews, and focus groups. EBCD research regarding hospital services and architectural issues has involved input from nurses, doctors, and patients as “participators” in the healthcare environment. After an initial individual survey, the various groups come together to finalize an approach to service design that all agree would be mutually beneficial. However, when deciding on architectural design rather than healthcare service procedures, there is a different focus for the EBCD process. Building design issues require stakeholders to comment on their experience with their physical built environment rather than service provision. Further, the EBCD model requires stakeholders, in the final phase, to share the results of their focus group deliberations with design professionals.

Researcher comments have suggested that input from stakeholders is limited by their lack of experience with the design process. This current study aims to address this issue. For the design team the question is: What information do we get from the stakeholders? How can we ensure this information is successfully considered as input for the final design? An important source of information about a designed physical space is the post occupancy evaluation (POE). The POE process, inter alia, assesses the functionality of the built space. Here functionality addresses the question: Does the building do what it was designed for in an effective and efficient way [5]. Van der Voordt and Van Wegen (2005) argue that the ‘functionality’ of a built space can be measured in terms of nine elements: reachability, accessibility, efficiency, safety, spatial orientation, privacy, health and well-being, interior climate, and sustainability.

In assessing the functionality of the current cardiac health unit, the author has selected certain of the above elements as a basis for user input. Requiring stakeholders to think about their experiences and describe them in this structured format will minimize the problems of lack of experience and expertise in providing useful input. A structured assessment of stakeholder experience that is based on an architectural model will help focus user thinking and further provide information that is relevant to designers.

The aim of this study is to determine if a structured model for assessing user input will provide more relevant information for the final stage of the EBCD process involving interaction with design professionals. The need is to provide a guideline for information gathering that will enhance the quality and relevance of information available from stakeholders. Although there have been other methods of categorizing this information, the author argues

that a structure that is already part of the building evaluation process will be more successful. Using the categories for building functionality suggested by Van der Voort and Van Wegen (2005), as a guideline, will make it easier for users to organize their thoughts about their experiences. The users can then provide a more focused opinion regarding their perception of the current CHU space and provide comment for any new design. Further, the information forthcoming will be more synchronous with the conceptual thinking of designers and thereby enhance any subsequent interaction between users and design professionals.

The outcome of this study will provide a model for assessing stakeholder input for the final stage of the EBCD process, wherein the design professional seeks input from users of a built environment.

2. Background The current Cardiac Health Unit (CHU) at Maharat

hospital was established some twenty years ago. Historically, the hospital has used an “incremental space adaptation strategy” for continuing development [15]. Incrementalism is an approach to development that is used when there is a need for rapid expansion of physical facilities. At the time there was a perceived need for a cardiac health unit. The physical space initially allocated to the proposed unit was a specific square-footage. Facilities required for the center had to be designed to fit the allocated space. There was no consideration given to sustainability/flexibility, and definitely limited interest in a patient-centered approach to design. Hospital design was, at that time, based on the requirements of medical specialties as opposed to concern for the patient [10]. The current cardiac health unit layout is shown in Figure 1.

For the purposes of this study, in terms of public and private space, the physical space allocated to the CHU has been categorized as three separate zones; medical staff areas; medical examination area, and waiting (public) area. Medical staff areas are places that are off-limits to the general patient population, and consist of rooms used by doctors and nurses in their organizing and administrative roles. Medical examination areas include specific medical examination rooms: echocardiogram, ECG, exercise stress test, pacemaker review, congenital heart disease monitoring, and general diagnostic interview room. Entry to these areas is at the behest of medical staff. Waiting area includes those public spaces that patients may freely use. (See Figure 1).

The proposed experience-based co-design (EBCD) model to be used in this study is a participatory process, involving active input from medical staff and patients. Bate and Robert (2006) suggest a basic model for EBCD as a multi-stage process. The initial step requires the gathering of information from stakeholders as individuals. Individual

762 A Structural Format to Facilitate User Input for the Co-design of a Cardiac Health Unit

profiles are then analyzed and shared with members of the specific participant group. The different participating groups come together to share experiences, and through various strategies, decide on recommendations for change. Most healthcare research using EBCD, to date, has focused on the re-design of procedures and services [3]. There has been little discussion of its use in the analysis of healthcare facilities (built environment). This current study focused on user opinions about the built structure of a hospital clinic rather than the services provided.

Waroonkun (2019) when investigating nursing staff input to the design of a new outpatient department, proposed a modified model of EBCD. Essentially this model includes a final stage where the user groups meet with design specialists and jointly develop a working outline for a potential design for a new, or revised, facility. A more complete version of the model is shown in Figure 2. Fay, Carll-White and Harrell (2016) also argue for the use of a final charrette, wherein user input has a significant role in design outcome. The charrette process is seen as a concrete way to apply the results of a post-occupancy evaluation.

Prior research has identified a number of limitations when using the EBCD and POE strategies to elicit user input. A consistent observation relates to the difficulty users experience when asked to comment on an issue (building design) where they have limited conceptual knowledge or experience [8,10,16]. Jellema, Annemans and Heylighen (2019) suggests that, when examining the role of architecture, most individuals would have difficulty describing how they experience a ‘space’. In an attempt to resolve this problem, several authors concerned with design of physical spaces have provided initial user surveys based on a number of macro environmental categories.

There is a recognized relationship between a hospital’s-built environment and patient healthcare outcomes [13,14]. This necessitates that any assessment of the hospital environment includes environmental variables that are known to have such an impact. Fay, Carll-White and Harrell (2016) have argued that any such variables must result from extant evidence-based research. In an assessment of a hospital Emergency Department they surveyed staff, visitors, and patients seeking comment on built environment design variables. Their survey instrument included core questions related to audio environment, visual environment, safety enhancement, wayfinding systems, treatment rooms, family support spaces, staff support spaces, privacy, and communication. In an extensive review of POE assessment tools, Brambilla and Capolongo (2019) found that most POE assessment tools, used in hospital/clinic environments, have a strong emphasis on healthcare variables and sustainability. The healthcare variables included: safety enhancement, visual environment, audio environment, staff and doctor space features, patient room features, wayfinding features, family/visitor space features, and sustainability. Waroonkun (2019) used survey items drawing on

evidence-based design literature and healthcare environment research. Nursing staff feedback regarding an outpatient department was assessed for several categories: workplace layout (physical layout of space), safety (both nursing staff and patients), general ambience (lighting, noise, greenery, color), privacy (staff and patient), and convenience facilities (canteen, etc.).

Experience based co-design is equivalent to post-occupancy evaluation (POE) in as much as they both aim to improve future building design using some form of input from intended users. Post Occupancy Evaluation (POE) has been defined by several authors [2,4,5]. Essentially, POE asks: Does the built structure achieve the purpose for which it was designed? What is the inter-relationship between the built environment, user experiences (e.g. patients, doctors, nurses), and operational outcomes of the building? [9]. How does the building performance compare with user expectations? [1]. Van der Voort and Van Wegen (2005) argue that POE deals with the “functional quality” of the building. Functional quality “requires a building [built space] to have good accessibility, to provide sufficient space, to be arranged efficiently and comprehensibly, to be sufficiently flexible, and to provide spatial and physical conditions that will ensure a safe, healthy, and pleasant environment” (p.4). They further argue that the functional quality of a building can be evaluated by considering nine specific criteria: reachability, accessibility, efficiency, flexibility, safety, spatial orientation, privacy, health and physical well-being, and sustainability.

The objective of the EBCD in this study is to improve the design outcome for a new cardiac health unit, as part of a hospital environment, using input from prospective users. Providing comment regarding built environment design variables is somewhat beyond the knowledge and experience of medical professionals and patients [12]. Thus, a guiding structure that can facilitate opinion regarding the built environment is desirable. The instrument developed for this study was based on the elements of ‘functionality’ as defined by Van der Voort and Van Wegen (2005) [4]. The macro areas of the instrument were also linked to extant healthcare environment variables based on evidence-based literature search. This instrument differs from other measures in that it prioritizes the ‘functionality’ characteristics of a built environment over healthcare related issues. The instrument thus caters for lack of user knowledge and expertise, includes health related concepts, and links to building functionality as an integral aspect of post-occupancy evaluation.

As the current study relates to a defined space (CHU) within the hospital building, it was limited to considering only the following functionality elements: • Accessibility: ease with which users can enter the

space and use rooms and services intended for them. • Efficiency: optimum support for anticipated activities,

includes spatial layout, dedicated areas, ease of cleaning and maintenance.


• Safety: especially user safety, must cater for all potential users considering strength, mobility, handicaps. Need to consider environmental factors; e.g. floor surfaces, adequate lighting, management of space, no sharp edges or corners.

• Spatial Orientation: understandable layout: e.g. recognizable functional units, clear distinction between public and private areas; clear and comprehensible signage; organizational measures: reception/information areas.

• Privacy: visual: control over whether to be seen or not (examination room); auditory: not disturbed by noise of others, confidential communication not overheard by others; social/ territorial control over need to be “private”; control over levels of social contact.

• Health and well-being: light (daylight, suitable intensity, reflective surfaces, color); noise (no irritating noises-especially in cardiac stress situations); interior climate: room temperature-avoid extremes; ventilation-removal of uncomfortable odors; control of humidity

Using these criteria as part of an assessment regime, stakeholders can give a more focused opinion regarding their perception of the current CHU space and indicate preferences for inclusions or modifications in any new designs.

3. Materials & Method The research proposal was presented to Hospital

Management and the Senior Cardiac Registrar. Approval was granted on the condition that nursing staff were consulted prior to selection of patient participants.

3.1. Participants

Participants in this study were drawn from three distinct groups of users of the CHU: patients, nursing staff, and medical practitioners. Each participant was approached individually to invite their involvement in the study. The three-stage process (survey, focus group, and joint working group) and the participant’s potential involvement were fully discussed. Within the ‘Doctor” group several medical professionals declined to be involved, citing ‘busy schedule’ as the reason. Nursing staff were keen to be involved. Patients were initially screened by the research team (with the advice of the Senior Nurse) before they were approached. Very elderly patients and those with more serious cardiac issues were not approached (this may have some repercussions regarding the ‘representativeness’ of the sample, but the author was prepared to err in favor of patient welfare). Further, given the difficulty for patients to attend the hospital (travel times, transport availability), only those patients who were scheduled to attend the CHU on a future date were approached

3.2. Survey Instrument

A survey questionnaire was designed to elicit participant feedback about various aspects of the CHU built space. The space was considered as three functional units: waiting area (public), examination area (public/private), and medical staff area (private). The survey items were based on the elements of a functional analysis (as part of a POE) of a built environment. More particularly six macro areas were selected as being suitable for this study: accessibility, efficiency, safety, spatial orientation, privacy, and health and well-being [4]. In deference to prior evidence-based research of hospital environments [14] questions items about “greenery” and artwork were also included in the survey. Participants were asked to rate their level of agreement for individual items related to a particular macro element. The survey used a Likert format, where respondents score ‘1’ meaning ‘strongly agree’ through to ‘5’ meaning ‘strongly disagree’. A score of ‘3’ represents a ‘neutral’ response – no committed feeling either way. A mean score and standard deviation were calculated for each item. Patient views on medical staff areas were not elicited as those areas are not relevant to patient use. This necessitated the development of two survey forms: items regarding the medical staff area were absent from the ‘patient version’ of the survey questionnaire. The language used for the survey instrument was Thai. Translations have been made for this report.

3.3. Process

Phase 1 (Survey Completion): Participants were first given the survey form to be completed individually at the hospital and returned to a member of the survey team on completion. Survey team members were on hand to deal with any problems, otherwise the results were confidential. The survey results were tabulated for each group and a copy was sent to each member of their group. Participants were asked to review their group’s results and think about the reasons for their own responses. The report and their thoughts would be part of a group discussion in the next phase of the study.

Phase 2. (Focus Group): Members of each participant group met as a distinct ‘focus group’ (doctors, nurses, and patients). A future date for each focus group had been arranged and participants were asked if they could attend on that date. For patients, the cardiac unit was able to schedule future appointments so that patients would be free to participate (medical consultation in the morning and research post-lunch afternoon. A free lunch was provided by the hospital). For doctors and nurses, management agreed to cover participants’ time off by rostering extra staff for that period.

In each focus group session participants were given a copy of their respective group’s survey profile again. Focus groups met in the CHU meeting room (quiet, private space, seating for twenty people). The focus group facilitators


were members of the research team who had undergone a short course on focus group management. All facilitators had previous focus group experience [18]. After initial introductions and explanation of the purpose of the focus group, the facilitator-initiated discussion using the survey macro elements as a discussion structure. The opening question in each case was, “What are your thoughts on the items related to factor X”. The group was encouraged to express their views freely. The facilitator explained there was no ‘correct’ answer and that all thoughts, ideas, suggestions were valuable.

Audio recordings of each focus group were kept for later analysis. Major themes and common ideas about each element were assessed and noted. At the close of the focus group discussion each group was asked to nominate three members to participate in a Joint Working Group (Phase 3). Results of the Phase 2 focus groups were sent to all members of the Joint Working Group (JWG) prior to its meeting.

Phase 3 (Joint Working Group): Because of the small number of participants in each user group, the ‘joint group sessions’ stage of the model (Fig. 1) was omitted. A joint working group (JWG) made up of three members of each of the three participating user groups was established (N=9). The JWG met in the same venue as Phase 2. Each of the participants was again given a copy of the Phase 2 focus groups’ discussion profiles. The research team leader (author) was present at this session initially. He explained the objective of this session to the group: to provide their thoughts on the current CHU built area with a view to making design adjustments in the future. The author stressed that the discussion was “not just an academic exercise” but that a future design team would be keen to know “what works and what doesn’t”. Again, the facilitator opened the session with an introduction phase, an explanation of the purpose of the session, and an opening question. As for phase 2, discussion was based on the macro elements from the survey. The joint working group was asked to discuss issues raised in the Phase 2 focus group sessions. As a result of their discussion they were asked to compile a list of suggestions and recommendations for the re-design of the current CHU or the design of a new CHU. The JWG session was recorded and later analyzed and summarized. The report of the recommendations and their rationale would provide the input for later discussion with design professionals.

4. Results Participants in the study were drawn from one of three

groups (Doctors, Nurse, and Patients). The number of doctors available to the Cardiac Health Unit is ten. In order that no one group dominated the study, the number of participants was held at ten for each group (N = 30)

Doctors: the doctor group (N = 10) consisted of eight (8)

males and two (2) females. Three (3) were senior cardiac consultants, the remaining seven (7) were cardiac registrars. All physicians had at least five years’ experience as a cardiac specialist and three years working in the hospital CHU.

Nurses: all of the nursing group (N = 10) were female. All participants had at least two years’ experience in the cardiac unit.

Patients: Patients in the study (N = 10) were male (N = 4) and female (N = 6). Age range for patients 21-40 years (N = 3), 41-60 years (N = 5), over 60 years (N = 2). Many elder patients were excluded from the study as a result of selection conditions applied.

Survey results are displayed in Table 1. For each item the participants indicated their level of agreement with the item statement. A low-level score (< 3) shows general agreement with the statement. A high-level score (> 3) indicates a level of disagreement. A score of ‘3’ represents a ‘neutral’ response. A detailed analysis follows:

Doctors: Survey results for doctors suggest doctors have little concern about the CHU built area in general. They have three areas of concern: the amount of space available in the examination room (Item 2.3, x̄ = 4.1), and in the medical staff area (Item 2.4, x̄ = 3.9), and there was some concern about movement within the CHU space in general (Item 2.6, x̄ = 3.9, Item 3.7, x̄ = 3.8)

Nurses: Nurse survey profile suggests several areas of critical concern. Accessing areas within the treatment area is of concern (see survey items 1.4, 1.5, 1.6). In terms of building efficiency, nurses have concerns regarding all aspects (items): waiting area, examination area, and general workflows within the space. This is reflected also in nurses’ opinion regarding the demarcation of spaces (Item 5.2, x̄ = 4.1). They had an issue with safety in areas used by patients (Items 3.1 and 3.2), and also about general movement in the CHU (Item 3.7, x̄ = 4.1). Nurses shared patients’ concern for privacy in areas where staff/patient interaction occurs (Items 4.1, 4.2, 4.3). Nurses felt there was limited suitable space for confidential discussion in the medical staff area (Item 4.4).

Patients: Patients concerns related to accessing the examination rooms within the CHU (Item 1.4, x̄ = 3.7). They expressed concerns about space and facilities in the waiting area and examination room (Items 2.1, 2.2, 2.3). Privacy issues were also registered as sources of dissatisfaction (Items 4.1, 4.2, 4.3). The general layout of the CHU was seen as confusing for patients (All items for “Spatial Orientation”). The ambience (“well-being” element) of the CHU was generally acceptable but with some concerns about the noise level in the waiting area (Item 6.4), and the temperature in the examination room (Item 6.2). In terms of aesthetics, patients felt that the inclusion of some type of greenery is appropriate (Item 6.13). That view was not shared regarding the introduction of artwork/photos. Overall patients did not feel at ease in the CHU (Item 6.15)


Figure 1. Floor plan of the current Cardiac Health Unit

Figure 2. A more detailed version of the EBCD model


Table 1. Questionnaire Responses

POE Element Item Doctors Mean (SD.)

Nurses Mean (SD.)

Patients Mean (SD.)

Accessibility 1.1 Entry to the CHU is easy to find and use 1.5 (0.52) 1.4 (0.51) 2.6 (0.51) 1.2 Getting to the Registration Desk is easy 2.5 (0.51) 3.6 (0.70) 3.2 (0.63) 1.3 The waiting area is easy to find 1.5 (0.52) 2.5 (0.53) 3.2 (0.63) 1.4 Moving to the examination room is easy and unobstructed 3.4 (0.52) 4.3 (0.67) 3.7 (0.67) 1.5 Accessing the medical staff area is easy and unobstructed 3.0 (0.47) 4.1 (0.74) N/A 1.6 Wheelchair access to all areas is easy 3.2 (0.42) 4.0 (0.67) 2.9 (0.57) 1.7 The CHU has a welcoming feel 2.5 (0.70) 2.8 (0.91) 3.1 (0.74)

Efficiency 2.1 Waiting area has sufficient space for its intended use. 3.3 (0.48) 4.5 (0.52) 4.0 (0.94) 2.2 Waiting area has enough facilities (chairs, water, etc.) 3.4 (0.51) 4.2 (0.78) 4.0 (0.82) 2.3 Examination room has enough space for use and equipment. 4.1 (0.73) 4.4 (0.70) 3.7 (0.67) 2.4 Medical staff areas have enough space for function and equipment 3.9 (0.57) 4.4 (0.70) N/A 2.5 Medical equipment is easily available when needed. 3.3 (0.48) 4.5 (0.52) N/A 2.6 Moving to different areas of the CHU is easy and unobstructed 3.9 (0.57) 4.1 (0.57) 4.0 (0.67)

Safety 3.1 Waiting area provides a safe environment for all users 3.1 (0.57) 3.9 (0.74) 3.7 (0.82) 3.2 Examination rooms provide a safe environment for all users 3.2 (0.42) 3.8 (0.79) 3.3 (0.48) 3.3 Medical staff areas provide a safe environment for all users 3.0 (0.67) 3.0 (0.67) N/A 3.4 Internal equipment and furnishings use a safe design and materials 2.8 (0.42) 3.2 (0.63) 2.5 (0.53) 3.5 CHU is a safe environment for wheelchair and disabled people. 2.5 (0.53) 3.2 (0.63) 2.6 (0.70) 3.6 Emergency safety equipment is visible and easily reached 2.5 (0.53) 2.0 (0.67) 2.6 (0.51) 3.7 Moving about in the CHU is safe and unobstructed. 3.8 (0.79) 4.1 (0.57) 3.8 (0.63)

Privacy 4.1 Conversation with nursing staff at registration is private 2.8 (0.63) 4.1 (0.74) 4.2 (0.63) 4.2 People outside could easily see the patient in the examination room 3.4 (0.51) 2.4 (0.51) 2.0 (0.67) 4.3 People outside can hear conversations in the examination room 3.9 (0.74) 2.7 (0.95) 2.4 (0.70) 4.4 The medical staff area provides sufficient privacy and security 2.9 (0.74) 3.9 (0.74) N/A

4.5 In the CHU I felt I have control of how I made contact with other people 1.5 (0.53) 2.0 (0.67) 3.5 (0.53)

Spatial Orientation 5.1 In the CHU it was easy to see where the patient had to go next 1.0 (0.0) 1.0 (0.0) 3.8 (0.79)

5.2 The separate ‘Public’ and ‘Medical’ areas are clearly defined 1.5 (0.53) 4.1 (0.74) 4.3 (0.67) 5.3 Different sections in the CHU had clear and understandable signs 2.4 (0.97) 3.6 (0.70) 4.2 (0.63) 5.4 The arrangement of rooms in the CHU is confusing 4.1 (0.89) 4.2 (0.79) 2.3 (0.95) 5.5 Moving from one section to another in the CHU is confusing 4.6 (0.52) 4.4 (0.70) 2.5 (0.85) 5.6 Waiting area is set up so that patients can sit together with family 3.1 (0.57) 3.8 (0.63) 4.3 (0.82)

Well-being 6.1 The temperature in the waiting area is comfortable 2.4 (0.52) 3.0 (0.67) 2.9 (0.74) 6.2 The temperature in the examination room is comfortable 3.3 (0.48) 3.0 (0.67) 3.7 (0.67) 6.3 The temperature in the medical staff area is comfortable 2.8 (0.42) 3.0 (0.67) N/A 6.4 The noise level in the waiting area is annoying. 3.3 (0.48) 2.4 (0.70) 2.4 (0.52) 6.5 The noise level in the examination room is annoying. 3.5 (0.53) 3.3 (0.48) 3.2 (0.79) 6.6 The noise level in the medical staff area is annoying. 4.1 (0.74) 4.0 (0.82) N/A 6.7 There is good lighting in the waiting area 2.5 (0.52) 3.2 (0.63) 3.1 (0.57) 6.8 There is good lighting in the examination room 2.4 (0.52) 2.8 (0.42) 2.5 (0.53) 6.9 There is good lighting in the medical staff area 1.3 (0.43) 1.6 (0.70) N/A 6.10 The ventilation in the waiting area is good - fresh air, no smells 2.1 (0.88) 2.2 (0.79) 2.8 (0.42) 6.11 The ventilation in the examination area is good - fresh air, no smells 2.3 (0.68) 2.7 (0.48) 2.8 (0.42) 6.12 The ventilation in the medical staff area is good - fresh air, no smells 2.1 (0.74) 2.6 (0.70) N/A 6.13 There should be plants or ‘greenery’ in the waiting area 2.9 (0.57) 2.8 (0.63) 2.2 (0.79) 6.14 Pictures on the wall would make the waiting area more relaxing 3.0 (0.00) 2.9 (0.74) 3.1 (0.74) 6.15 Overall, I felt comfortable using the CHU 1.5 (0.53) 3.1 (0.74) 3.7 (0.67)


4.1. Focus Groups

The above survey results provided the basis for discussion during the participant specific (doctor, nurse, patient) focus groups. Focus group input disclosed more detail regarding issues raised in the survey questionnaire. The time spent on this initial focus group discussion varied. Doctors completed their discussion in twenty minutes. Nurses spent more time together; discussing issues for about an hour. Patients were slow to start conversation among themselves but as confidence with the situation grew so did discussion. Patients spent some seventy minutes “chatting” together.

Doctors: Results of discussions suggest the main concern for doctors is the amount of space available. The medical examination areas are too cramped when medical personnel, equipment, and persons accompanying patients all require access to the space. This crowding is also a safety issue when moving about the CHU. The medical staff areas of concern for the doctors were the area set aside for doctors to write reports and to interact with nursing staff on confidential matters. Doctors found the CHU set up (design) to be workable for them. They had no issues with the general physical ambience of the unit.

Nurses: Nurse focus group was a dynamic and engaging session. All nursing staff made considerable input to the discussion. The fundamental concerns were accessing work areas and the lack of available space to perform their duties efficiently. The lack of storage space for equipment etc. resulted in access and flow areas being used for storage, thus causing obstructions and time wasted. The location and size of the storage area was a significant issue. Equipment storage space was not sufficient and accessing equipment (and patient records from the same space) mean traversing an obstacle course between storage room and destination. The fact that “public” and “medical” space are not clearly defined meant that equipment and patients awaiting access to exam room were located wherever space was available. Nurses were concerned about the level of privacy in their professional and patient interaction conversations. Because of space issues and overcrowding in examination room areas, they also had concerns about patient’s visual privacy. A particular item of “irritation” was a noisy air conditioning unit above the patient registration area that made it difficult to hear and be heard (a maintenance issue)

Patients: Patients generally found the experience in the CHU lead to anxiety and confusion. Patients’ experience in the waiting area: cramped seating – or no seating, lack of flexibility in seating arrangements (especially if patient was in a wheelchair), lack of amenities at or nearby, added to patients’ initial anxiety levels. Notwithstanding prior experience in the unit, the lack of appropriate signage and confusing layout was a cause of concern. Reflecting a theme from the nurses, patients were also concerned about the lack of privacy in the waiting area, at the registration

desk, and in the examination room. They felt that visual (and to some extent auditory) privacy was lacking. General ambience of the space was acceptable. However, there was comment about temperature regulation in the exercise stress test room (too hot and no breeze). Elderly patients found the waiting area too noisy and worried that they would not be able to hear when their name was called. On the issue of lighting, the absence of windows and natural light was never raised (The current CHU space has no windows).

4.2. Joint Working Group

The Joint Working Group (JWG) was made up of nine people in total. The members of the JWG were selected by their peers in their focus group. Doctors (3) were all male, and junior registrars. The doctor representatives were ‘volunteered’ by the senior physicians. The nurses (3) were all female and represented different levels of experience at the CHU. Nurses chosen were considered by their group to be experienced nurses and confident speakers. Patient members (3) were one male (41-59 years age group) and two females (41-59 years age group, 60+ years age group). Patients were chosen because of their experience in the CHU (multiple visits) and their confidence to speak up. The joint working group session was slow to start initially. There was some concern about communication between people of perceived different social status. However, after one of the senior patients spoke openly and frankly, the group warmed to each other and began to act like a team on a mission. The time taken for a final output by the group was nearly three hours (include coffee break).

The discussion agenda for the JWG was based on the elements of functionality as used in the original survey. Generally, the members of each focus group were supportive of one another’s focus group discussion points. Results of the joint group discussion are reported below.

Access: The public area entrance is not wide enough to enter for wheelchairs and gurneys, especially as the entrance is through a crowded waiting area. The central area of the CHU and access to the examination rooms is often blocked by equipment and/or patients waiting for assessment. The medical equipment and records storage area location means nurses have obstructed access to this area.

Efficiency: The waiting area lacks sufficient space for current use, has insufficient seating and little potential to arrange furniture to cater for special users (e.g. family with wheelchair patient). There is insufficient space in the medical examination rooms to accommodate equipment, medical personnel, and patient group. There is a lack of specific rooms for some types of assessment, that by default, are conducted in open space (e.g. Fig.1, areas: 2.4, 2.6, 2.7). Location of registration counter in the central area leads to overcrowding and obstructions. There is limited


dedicated space (room) for doctors and nurses to complete paper work and converse about medical/patient matters. There is no specific dining and relaxation area for medical staff. The meeting room is essential (teaching hospital) and is suited for purpose.

Safety: All areas where the public are involved, lack several safety installations appropriate to CHU clientele e.g. hand rails, non-slip floors, seating with armrests.

Spatial Orientation: The CHU lacks sufficient space for its effective functioning resulting in overcrowding and obstructions. The layout of the unit is confusing for patients in terms of location of specialist sub-units. The storage room is located at the furthest point from where equipment or records are required. Movement from the waiting area to the toilets means patients must traverse the central function area of the CHU. Adding to the confusion is the considerable overlap between “public” and “restricted area”. There is no clear signage displayed.

Privacy: Seating in the waiting area is cramped, making it difficult to organize a ‘family unit’, thus it is near impossible for patients and family to have a private conversation. Patients in the examination rooms are clearly visible to people in the central area (which often includes other patients waiting outside the examination room). Conversations between patient and medical staff can be heard by others. This is especially the situation at the registration counter.

Well-being: The general ambience of the CHU was considered basically acceptable. The temperature in exam rooms needs local control so it can be adjusted according to room usage. The ambient noise in the unit can reach a high level. The group agreed that this was simply caused by the presence of large number of people accessing and involved in the unit.

The final broad overall comment from the group indicates several areas to be considered in future designs. Many of the problems are the result of overcrowding due to lack of space. The second point of concern was the poor layout of the unit. There was no logical strategy connecting the patients required consultation sequence and the location of areas where the consultation would be conducted. Overlapping of movement pathways within the unit causes considerable problems. The group felt the CHU was generally not user-friendly.

5. Discussion Experience based co-design and post occupancy

evaluation, when used as a means to inform the design of built spaces, share a common strategy. They both incorporate the opinions of current or intended users regarding a built space. These opinions indicate whether or not the planned space does in fact reflect its end purpose. In the case of the hospital Cardiac Health Unit the relevant users include doctors, nursing staff, and patients (and

family/friends). Obtaining relevant and useful input from groups who

have no design experience is problematic [7,16,18]. Design professionals are concerned that users are lacking in design conceptual knowledge and experience [10]. Yet the user is at the core of EBCD and POE analysis. Design strategies “need a deeper understanding of the problems and realities of people for whom we are designing” [9]. This study aimed to minimize the above perceived difficulty by providing users with a ‘guideline’ to express their opinions and experiences. The instrument used a structure based on elements of building functionality [4]. These elements were also linked to healthcare environmental variables based on EBD research [9]. The unique perspective of this instrument is its focus on the ‘functionality’ characteristics of the built environment.

The results of the initial survey, and later focus group discussions, elicited considerable relevant information. That the three participant groups (doctors, nurses, patients) clearly showed different response profiles suggesting the instrument is capable of tapping differences in perceptions. The end-point of the process (joint working group) resolved issues using the criteria specified in the instrument. The result is an overall perspective of the Cardiac Health Unit (CHU), rather than a comment on each of the contributing variables in isolation. The instrument fosters an integration of the users’ various perspectives, thus giving an overall impression of the Cardiac Health Unit. The issues discussed in the focus groups, although related to healthcare environment variables, were nevertheless discussed in the context of the function of the CHU. Hence, the users were able to decide that amount of “physical space” available was a primary concern. Further, in regards to the feeling of confusion in the patients, the working group decided on a cause for this problem. The absence of a logical spatial layout connecting patient treatment flow and the location of the relevant treatment areas was considered the cause of patients’ confusion. An analysis of the full outcome of the joint working group discussion provided valuable insights. By understanding the concerns of the users resulting from this assessment, design specialists will have a valuable set of inputs to inform their final building design.

Although the structured format for gathering user input was beneficial in providing focused guidelines for discussion, there was an issue that arose during the joint working group discussion. The relative status of participants has been identified as an issue [6,7]. In the early stages of the joint working group discussion, nurses and patients were observed deferring to doctors, and patients in turn deferring to nurses. However, after some pertinent comments the situation altered. In response to a doctor’s comments, a senior nurse suggested that the doctor was not always present: “before you arrive” and “after you’ve gone” were the bases to her reply. The


medical staff were seemingly more empathetic after a very senior patient explained the anxiety, fear, and confusion felt by most patients when they were at the CHU. After this exposition, the entire working group began to meld and focus on the discussion structure at hand: “We need to focus on the problems we have experienced so we can make positive suggestions” [Participant nurse comment]. A similar group dynamic was observed by Boström, Hillborg and Lilja (2017) when medical professionals and patients were involved in discussion groups. The authors observed that over the course of the meeting there develops a sense of mutual understanding and a trustful relationship.

A limitation of this current study may be that the small number of participants mitigates against any meaningful statistical analysis. However, results suggest that participant comments appear to be all encompassing. The inclusion of more users in each participant category, or in each step of the process, would most likely not identify any missed problem areas. It is possible, of course, that the strength of the observation (agree/disagree) may alter.

6. Conclusions The aim of this study was to develop a suitable survey

instrument to assess stakeholder feedback regarding a built environment. The results of the present study indicate that using a POE based, structured assessment strategy provides a solid guideline for determining a wide range of design issues from a user perspective. The strength and impact of the instrument is its ability to tap into a broad functional view of the users experience of a built environment. Its use has improved communication within user groups and will enhance subsequent discussion of built environment design variables with design specialists.

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DOI: 10.13189/cea.2020.080504

Performance of CO2 Cured Sugar Cane Bagasse

Ash Concrete in Marine Environment

T. Santhosh Kumar1,*, Balaji K. V. G. D2, Ch. Sandeep Reddy2, K. Chitti Babu1,

Ch. Lakshmi Sowjanya2

1GITAM School of Architecture, GITAM (deemed to be University), India 2Department of Civil Engineering, GITAM (deemed to be University), India



(a): [1] T. Santhosh Kumar, Balaji K.V.G.D, Ch. Sandeep Reddy, K. Chitti Babu, Ch. Lakshmi Sowjanya , "Performance

of CO2 Cured Sugar Cane Bagasse Ash Concrete in Marine Environment," Civil Engineering and Architecture, Vol. 8, No.

5, pp. 771 - 776, 2020. DOI: 10.13189/cea.2020.080504.

(b): T. Santhosh Kumar, Balaji K.V.G.D, Ch. Sandeep Reddy, K. Chitti Babu, Ch. Lakshmi Sowjanya (2020).

Performance of CO2 Cured Sugar Cane Bagasse Ash Concrete in Marine Environment. Civil Engineering and

Architecture, 8(5), 771 - 776. DOI: 10.13189/cea.2020.080504.


Abstract A large amount of industrial and agro wastes

mostly end up in landfills and not much attention is given

to these wastes, which cause environmental problems. Few

of the industrial and agro by-products such as fly ash, sugar

cane bagasse ash and silica fume act as pozzolanic

materials in preparation of blended cements which provide

satisfactory alternative results in waste management. The

main goal of this research is to check the durability

properties of carbon dioxide cured sugar cane bagasse ash

concrete when exposed to marine environments. A set of

different concrete mixes were prepared by partially

replacing the cement with various percentages of

sugarcane bagasse ash (0%, 5%, 15%, 25%) and 10% of

silica fume in each mix and then these specimens were

cured in water for 28 days, in CO2 gas for 8 hours and in

dry ice for 8 hours. After curing, these specimens are

exposed to seawater for a period of 28 days, 90 days and

120 days, and then tests are conducted for compressive,

tensile, and flexural strength. The test results indicate that

replacement of cement with 5% bagasse ash & 10% silica

fume showed better effective results when compared to all

other percentages of replacements. The specimens cured in

CO2 gas showed similar results as that of water cured

specimens while the specimens cured with dry ice showed

a loss in strength.

Keywords SCBA, Silica Fume, CO2, Gas Curing Dry

Ice Curing

1. Introduction

Reducing the usage of natural resources by partially

replacing cement with different pozzolanic material such

as silica fume, sugar cane bagasse ash, and replacing water

with carbon dioxide for curing, it was found that 80% of

strength was achieved for 8hrs of CO2 curing compared

with 28 days water curing specimen [1]. Durability

properties have studied for recycled aggregate concrete

specimens cured with carbon dioxide, it was shown that

compressive strength at 72 hrs of CO2 cured concrete was

similar to 90 days water curing and split tensile strength

showed higher results compared to 90 days water cured

results, higher chloride penetration resistance was

observed [2]. To achieve the rapid strength two curing

methods were followed for the concrete made up of

recycled aggregates. samples cured with pressurized

carbon dioxide curing showed better results than flow

through carbon dioxide curing [3], [4]. This work aims to

examine the potential absorption of concrete by carbon

dioxide. For this study, dry ice was used [5]. After 2hrs of

curing the compressive strength of dry ice cured samples

was 22.12% more than the water cured samples [6]. Green

concrete using aggro waste [SCBA] for a water-cement

ratio of 0.42 showed that at 15% of replacement the

strength of concrete showed best results at 28 days of

curing compared to other percentages (5%,10%,20%,25%),

at 28 days of curing for 20%,25% replacement samples

772 Performance of CO2 Cured Sugar Cane Bagasse Ash Concrete in Marine Environment

showed less split tensile strength [5], [7]. Investigated the

possibility of sugarcane bagasse ash, micro silica as

replacement of cement for lightweight weight concrete for

a water-cement ratio of 0.4. for 15%, 20% and 25%

bagasse ash showed 8%, 24%, 35% reduction in

compressive strength. 13% of increase in compressive

strength was observed for 5% replacement. Due to the low

ability to occupy space, the water absorption was increased

by increasing the percentage of replacement. 5% of

bagasse ash replacement showed optimum results

compared to other percentages of replacements [8]. In

order to study the potential of the reuse of industrial wastes,

Hermawan et.al studied the mechanical and dimensional

properties of cement bonded particles cured with CO2 gas

and it was found that C3S hydration was accelerated due to

CO2 curing which improves the strength of concrete [9].

Suitability of sea water for curing and compressive strength

of concrete was found that a loss of 6% was observed for

seawater cured samples at 180 days of curing, 10% loss

was observed when concrete made with seawater and cured

with plain water [9]. Studied the fluence of sea water, sea

sand for curing and mixing for concrete and it was found

that there is a slight increase in compressive strength of

concrete mixed with fresh water and cured in sea water at

90 days of curing and no change was observed in tensile

strength of concrete, and there is a decrease in flexural

strength of concrete was observed [10]. Ultra-high

performance of concrete made of sea water, sea sand and

silica fume for cement replacement was used and the

results showed that the concrete made with sea water, sea

sand, white cement and silica fume, quartz powder

achieved 28 days cube strength [11]. There is a slight

decrease in compressive strength and elastic modulus of

concrete made with sea water compared to fresh water

curing [12]. Types of aggregate affect the concrete volume

and the water permeability of concrete [13].

India contributes 6.6% (4th largest) of total world CO2

emissions, there is a need to capture and use CO2 in the

right way [14]. Major sources for carbon emissions are

fossil fuels and cement manufactures. Most of the world’s

energy generating from the combustion of fossil fuels and

it is the major source for greenhouse gases like CO2 etc.., it

is necessary to develop various methods to use these gases

in different practices [15]. Using Carbon dioxide for curing

of concrete offers a better substitute for water [16].

CO2 is a waste product produced from the industry,

therefore CO2 has to be either stored under the earth or

beneath the sea and it will be a problem at any point of time,

instead of that in the proposed research a large portion of

CO2 will go into the concrete and it forms a stable

compound and a part of it may go into the atmosphere but it

will be comparatively less and this is how it will effectively

utilize the Carbon dioxide.

2. Materials

2.1. Cement

53 grade OPC cement was used for this research, which

is having a specific surface area of 313 m2/kg, and

physical properties test results are shown in Table 1.

Table 1. Physical properties of cement

Specific gravity 3.1

Fineness of cement 8

Standard consistency of cement 31%

Final setting time of cement 320 minutes

Initial setting time of cement 85 minutes

Compressive strength at 28 days (MPa) 52.5

2.2. Aggregates

Natural crushed stones of angular shape were used as

coarse aggregates and river sand with a fineness of 2.73

from Zone 2 was used as fine aggregates.

2.3. Silica Fume and Bagasse Ash

Sugar cane bagasse having Specific gravity of 2.1 and

specific surface area of 2500m2/kg, particle mean size of

0.1-0.2µm was used. Specific gravity of 2.1, specific

surface area of 1500-3000m2/kg silica fume was used.

Table 2 gives the chemical properties of cement, SCBA

and silica fume.

Table 2. Chemical properties of cement, SCBA, SF

Chemical

Compound Cement SCBA

Silica

Fume

SiO2 20.12 63.00 85

Al2O3 5.77 31.50 1.12

Fe2O3 3.45 1.79 1.46

Na2O 0.34 - 0.5

CaO 63.68 0.48 0.8

MgO 0.3 0.4 0.8

LOI 1.47 0.71 0.6

3. Methodology

3.1. Experimental Procedure

Concrete cubes of size 100mmX100mmX100mm,

cylinders of size 150mmX300mm, prisms of size

100mmX100mmX500mm for a water-cement ratio of 0.45

with SCBA replacement of 0%,5%,15%,25% and silica

fume of 10% for each mix were casted. These specimens

are cured in carbon dioxide gas, Dry ice for 8 hrs and in

water for 28 days. These specimens were placed in

seawater for 28 days, 90 days, 120 days. All the specimens

were tested for compressive, split tensile strength, flexural


strength as per Indian standards [16] – [18].

3.2. Curing Methods

3.2.1. Water Curing

After casting all the test specimens were cured in water

for 28 days for the analysis of test results. Fig 1 shows the

water immersion curing of test specimens.

Figure 1. Water Curing

3.2.2. Carbon dioxide gas curing:

The process of using carbon dioxide for curing is called

carbonation. The carbonation helps to gain rapid strength

and improve mechanical properties of concrete. This

curing is done by two methods. A carbon dioxide cylinder

was used for pressurized curing and Dry ice (solid form of

CO2) was used for moist curing.

1000mm×500mm×500mm size metallic chamber with a

pressure capacity of 2Kg/cm2 was used for pressurized

curing. The specimens are kept in CO2 chamber for 8 hours

and maintained the same pressure till the end of curing as

shown in Fig 2.

Figure 2. Carbon dioxide chamber

3.2.3. Dry ice curing

The cubes, cylinders and prisms are cast and cured in dry

ice for a period of 8 hours as indicated in Fig. 3A. The

specimens are placed in dry ice chamber and sealed tightly

to avoid air entering inside and cured for 8 hrs. After curing

these specimens are placed in seawater for 28 days, 90 days

and 120 days for testing.

Figure 3. Dry ice curing

4. Results and Discussions

4.1. Tests on Fresh Concrete

To check the workability of concrete slump and

compaction factor tests were conducted for freshly mixed

concrete. Slum and compaction factor test results are

32mm and 0.94 respectively.

4.2. Tests on Hardened Concrete

The compressive strength split tensile strength, flexural

strength of concrete specimens cured with water, CO2 gas

and Dry ice samples were tested after 28 days, 90 days, 120

days of immersion in sea water.

4.2.1. Compressive strength:

At 120 days of exposure to sea water the concrete mix

made of 10% of silica fume, 5% Bagasse ash showed

higher results compared to all other concrete mixes. For 5%

of replacement, there is an increase in compressive

strength up to 20.5% for water curing, 17.5% for gas curing

and 17.8% for dry ice curing compared to conventional mix

at 120days exposure to sea water. There is a decrease in

compressive strength for a mix made with 15%

replacement of cement with bagasse ash showed 11.6%,

17.5%, 12.8% for water, gas and dry ice curing compared

to conventional mixes at 120 days in sea water. For 25%

replacement, the strength decreased up to 23.9% for water,

34.6% for gas and 36.33% for dry Ice cured specimens

compared with conventional mixes. Compared to water

curing gas, dry ice curing showed less strength at a

120days period. Gas cured mixes showed strength loss of

2.5%. For 0% replacement, 5.9% for 5% replacement,

8.93% for 15% and 13.74% for 25% of replacement

compared to water cured specimens. At 120 days of


exposure to seawater dry ice cured specimens showed

strength loss of 4.5% for 0% replacement, 7.6% for 5%

replacement, 8.8% for 15% replacement, 20.1% 25%

replacement compared to water curing. Compared to dry

ice curing, gas curing specimens showed a less strength

loss and it was observed that there is an increase in loss of

strength when the percentage of replacement increases. Fig.

4, Fig. 5 and Fig. 6 indicates the compressive strength of

concrete cured with water, gas and sea water respectively.

Figure 4. Compressive Strength of Water cured specimens

Figure 5. Compressive Strength of CO2 gas cured specimens

Figure 6. Compressive Strength of Dry Ice cured specimens

4.2.2. Split tensile strength

The split tensile strengths of the concrete for various

percentages of SCBA are shown in Fig. 7, Fig. 8, and Fig.9.

At 5% of replacement, the concrete specimens showed an

increase in strength approximately 2%, 11%, 18% for

water, gas, dry ice curing respectively compared to

conventional mixes. For a replacement of 15% the strength

was decreased approximately from 7% - 11%, 8% - 15%,

14% - 16% for water, gas, dry ice cured specimens

respectively compared to conventional mixes. For the

replacement of 25%, the water cured specimen’s strength

loss was ranged between 20%-22% compared to a

conventional mix, 8% -20% loss was observed in gas

curing compared with conventional mix of gas cured

specimens and 18%-21% of strength loss was observed

between conventional and bagasse ash 25% mixes cured

with dry ice curing. Figure 7, 8 and 9 indicates the split

tensile strength of concrete cured with water, gas and sea

water respectively.

Figure 7. Split tensile strength of water cured specimens

Figure 8. Split tensile strength of water CO2 gas cured specimens


Figure 9. Split tensile strength of Dry ice cured specimens

4.2.3. Flexural strength

The flexural strengths of concrete specimens with

various percentages of SCBA as shown in Fig. 10, Fig. 11,

Fig. 12. It was observed that at 5% SCBA replacement

there is an increase in strength approximately up to 7%-9%

compared to a conventional mix cured in water,10%-11%

strength was increased for gas cured specimens compared

with gas cured conventional mix and 10%-15% strength

increased for dry ice cured concrete specimens compared

with conventional concrete specimens cured with dry ice.

For 15%replacement of cement with SCBA, the strength

was decreased (4% for water cured specimens, 3% for gas

cured specimens and 4% for dry ice cured specimens) at the

age of 120 days. For 25% replacement of cement with

SCBA, at the age of 120 days, there is a decrease in

strength varies approximately 17% for water curing, 20%

for gas curing, and 25% for dry ice curing specimens.

Figure 10. Flexural strength of water cured specimens.

Figure 11. Flexural strength of CO2 gas cured specimens

Figure 12. Flexural strength of Dry ice cured specimens

5. Conclusions

Based on the above investigations, the following

conclusions can be summarized as follows:

1. Due to the larger surface area of SCBA compared to

cement particles, there is a decrease in workability as

the percentage of replacement SCBA increases.

2. 8hours of carbon dioxide curing achieved

compressive strength compared to that of 28 days of

conventional cured specimens.

3. There is 20.5% increase in compressive strength of

concrete mix made of 5% SCBA,10% silica fume

replacement compared to conventional mix cured

with water, 17.5% increase in compressive strength

for 5% SCBA,10% silica fume replaced mix

compared to conventional gas cured mix and

similarly 17.8% improvement was observed for dry

ice cured specimens.

4. As the percentage of replacement increases, the

strength loss also more.


5. At 120 days of seawater exposure the 15% SCBA

concrete showed strength loss up to 20% where as

25% SCBA concrete showed up to 40% loss was

observed.

6. The samples cured with water, CO2 gas (8hrs)

showed similar results. Whereas, dry ice cured

samples showed less strength compared to CO2 gas,

Water cured mixes.

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Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in

Developing Countries

Udomiaye Emmanuel1,*, Chukwuali Basil Chukwuemeka2, Kalu Cheche Kalu1

1Department of Architectural Technology, Akanu Ibiam Federal Polytechnic, Uwana, Nigeria 2Department of Architecture, University of Nigeria, Enugu Campus, Nigeria


Cite This Paper in the following Citation Styles (a): [1] Udomiaye Emmanuel, Chukwuali Basil Chukwuemeka, Kalu Cheche Kalu , "Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in Developing Countries," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 777 - 791, 2020. DOI: 10.13189/cea.2020.080505.

(b): Udomiaye Emmanuel, Chukwuali Basil Chukwuemeka, Kalu Cheche Kalu (2020). Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in Developing Countries. Civil Engineering and Architecture, 8(5), 777 - 791. DOI: 10.13189/cea.2020.080505.


Abstract Sustainable architecture searches for methods to lessen the adverse environmental burdens of buildings by efficiently and moderately using materials, energy and space. Ensuring sustainable development in multiple dimensions requires an essential factor such as sustainable architectural practice that inculcates assessment framework. Life Cycle Energy Assessment (LCEA) is a key component of Life Cycle Assessment (LCA) in which energy use at different life cycle stage of buildings is the only parameter analysed. In developing countries, defining sustainable architecture and environmental sustainability assessment in buildings remains a herculean task. The aim of the study was to examine the theoretical challenges associated with defining what we mean by calling a building “green” or sustainable architectural design and a post-positivism viewpoint on sustainability assessment of architectural design. The objectives are to review the criteria for sustainable architecture and conduct an LCEA of an existing residential apartment building in Abakaliki- Nigeria, using process-based Life Cycle Energy Assessment. The embodied energy intensity was found to be high at 6.10GJ/M2, while cement- based component was 8.8% by mass but accounted for 67.6% of the embodied energy. Consequently, it is imperative to carry out LCEA at the early stage of design and employ strategies to reduce embodied energy instead of focusing only on lessening the operational energy. Environmental and energy efficiency

approaches should be prioritized on a life cycle energy basis.

Keywords Architecture, Assessment, Energy, Environment, Sustainability

1. IntroductionAny professional that is involved in building design,

procurement, construction and building maintenance or other activities related to the built environment in recent years would have encountered in one way or another the term sustainability or sustainable architectural design. Sustainable development is the “development that achieve the needs of the present without hindering the ability of the future generations to meet her needs” [1]. Therefore, sustainable architecture advocates ways to lessen the adverse environmental burdens of buildings by efficiently and moderately using materials, energy and space. Arezon, Kalan; Oliveira & Eduardo [2] added that sustainable architecture deals with the use of deliberate technique of ecological and energy management in planning the built environment. Ensuring sustainable development in multiple dimensions requires an essential factor such as sustainable architectural practice that is equipped with an

778 Life Cycle Energy Assessment (LCEA) Approach: A Prospect for Sustainable Architecture in Developing Countries

assessment framework. It is the designer's insight and technical knowledge to implement the fundamental features of the practice i.e. to design and build in accord with the environment [3], sociocultural and economic aspects of a community [2]. Therefore, the enhancement of architectural design and ‘specifications writing’ for an all-encompassing accomplishment of the environment is relevant and crucial for; reducing, costs, lowering energy use/greenhouse gas emissions, and for finding actual resolution that not only accomplishes an improved economy and environmental performance but also as an assessment framework for architects [4]. According to Walker [5] architects have the responsibility to engage in life cycle energy thinking during the design phase through a coherent deliberation about a combination of issues like environmental sustainability, durability, longevity and appropriate materials. One of such environmental assessment tools or framework that enables the architect to ascertain the level sustainability of his design is Life Cycle Energy Assessment (LCEA). Life Cycle Energy Assessment (LCEA) remains a key component of Life Cycle Assessment (LCA) in which energy use at different life cycle stages is the single parameter analysed. According to IPCC -Intergovernmental Panel on Climate Change [6] “LCA is a standardized tool under the International Organisation for Standardisation (ISO) for the measurement of environmental impact of products and processes throughout their life cycle usually from cradle to grave”. Life Cycle Assessment (LCA) exemplifies an all-inclusive technique used to estimate the environmental sustainability of a product such as buildings at all stages in its life cycle. Architecture is a significant arena for sustainable innovation. This is because according to the UNEP [7] construction of buildings “accounts for 40% of total energy use, 40% of altogether raw materials use, 30% of solid waste generation, and responsible for about 33% of the global greenhouse gas emissions”.

Vision 2050 of the International Union of Architects -IUA is to realize carbon-free and low energy, thus sustainable buildings [8]. Unfortunately, the current practice in most developing countries is far and in opposite direction with regard to the vision. This could be as a result of the fact that sustainability has not be accorded the needed attention in the training of the architect [9]. A recent Nigerian study by [10-11] revealed that carbon emission intensity of buildings in Nigeria is significantly high related to the values obtained from developed countries. Udomiaye et al., [11] added that the high emission intensity was traced to high volume of non-structural concrete elements such as concrete fascia, non-load bearing columns and concrete parapets. Moreover, the paucity of knowledge that exists with respect to what makes sustainable architecture or green design, how emissions from built environments can be mitigated and how to assess environmental sustainability need to be filled. This can be done by involving

incorporation of established knowledge, advanced architectural design strategies, application of innovative technologies and development of sustainability assessment guidelines. Environmental sustainability assessment of design is pivotal to understanding sustainable architecture. Thus, the aim of this paper is to bring awareness to a shared practical issue of sustainable architecture and provide parameters for assessing sustainable architectural design with the view to make the buildings more efficient, functional, and sustainable. This was done through literature review and practical Life Cycle Energy Assessment of an existing residential apartment building as a case study.

1.1. Sustainable Design and Green Architecture

Sustainable design is a design concept that considerably reduces the adverse influence of construction and operation of buildings on the environment, economy and human health as described in figure 1, thereby enhancing the overall building performance during its Life Cycle. Therefore, Sustainable buildings need to be resistant to climate change and be adaptable, non-rigid and durable so as to enhance a building’s service life [12]. Sustainable architecture and environmental sustainability are integral to green building. According to Madhumita [13] the "green" architecture is a conscious effort to protect air, water, and earth by selecting eco-friendly building materials and construction methods. Green Architecture idea, often refers to as “sustainable architectural design” or “green building,” is the philosophy, science and building designed approach and constructed in harmony with environmentally responsive principles [14]. The primary aim of green architecture is to mitigate the amount of resources consumed (i.e. economy of resources) during construction, use and operation of buildings as well as curbing the damage inflicted on the environment and sociocultural life through carbon emission, pollution and waste. The basic objectives of sustainable design are to achieve; energy efficiency, renewable energy, zero carbon and application of the 3R rule-Reduce, Reuse, and recycle.

Figure 1. Sustainable design concept. Source: Author


1.2. Relevance of Sustainable Architecture

Many developing countries are going through speedy development because of the huge infrastructural evolution from formal and informal sectors. The process of embarking on infrastructural development to meet the housing need of the ever-increasing urban population has raised environmental sustainability concerns. Currently, due to an increasing understanding of human interface with nature, it is extensively acknowledged by the scientific community that consuming energy from non-renewable sources has caused significant environmental damage [15]. The principles of green design can effectively blend aesthetic and functionality to save planet earth. The design and sustainable construction, or "Green Building" is an opportunity to use our resources more efficiently, while creating more energy efficient and healthy homes [16]. Effective green building or sustainable architecture is relevant based on the need to; I) Reduce embodied and operational energy and

emission II) Minimize operating cost by increasing productivity

and less energy and water. III) Improve occupant health as a result of improved

indoor air quality. IV) Reduce environmental impacts, climate change

migration and adaptation

1.3. Main Criteria for Sustainable Architecture

Sustainable architecture is more than just energy-efficient buildings. However, Vujozevic [17] posited that energy efficiency is the most significant approach that gives an opportunity to address the three current issues: environmental damage, climate change and energy security. In practice, sustainable architecture or green design involves five main design considerations or principles as presented in figure 2. These are site development, material specifications, energy efficiency, conservation of water and indoor air quality [14]. Pursuing these principles requires organizing a vast range of practices, procedures, skills to lessen or mitigate the environmental burdens and impact on human health, It frequently highlights the advantages of renewable resources, e.g. using sunlight through passive/active solar, photovoltaic equipment as well as using plants, green roofs, reduction of rainwater run-off, rain gardens, and other techniques are used such as using energy efficient building materials [18]. However, the practices or technologies adopted in green design or sustainable architecture are continuously developing and might actually vary based on regional differences, but the central philosophies are constant from which the technique is derived. Energy efficiency of building is a key factor in the search for sustainability in architecture [19]. Hence, understanding energy use in building could as well be a panacea for sustainable architecture.

Figure 2. Basic Elements of sustainable Architectural Design


2. Material and Methods

2.1. Energy Use in Buildings and Assessment

As earlier mentioned, the knowledge of energy use in buildings and its assessment framework are fundamental to understanding sustainable or green architecture. The rising fears around the preservation of the eco-system from late 1980s has made energy use of buildings to be closely monitored than previously, principally with regards to resource depletion, local/regional pollution and global warming, [20]. According to Ezema et al., [10] and Dixit [21] these forms of energy are consumed either directly or indirectly in a primary or delivered form. For example, in Nigerian scenario, the residential sector accounts for most of the final energy consumption with 57.8% [22]. Energy consumption throughout the life cycle of buildings consists of embodied energy, operating energy and demolition or decommissioning energy. Thus, the framework creates the fundamentals for energy efficiency procedures in the building industry, this underscores the relevance of LCEA in architecture and the built environment in general.

2.2. Embodied Energy

Embodied energy is the total energy expended in raw material extraction, manufacturing as well as energy used for the construction, maintenance of the building and haulage of raw and finished materials. Embodied energy consists of two parts: initial and recurring embodied energy [23-24]. The energy used in producing a building - materials production, haulage of materials and site construction (Manual and Machine) is referred to as initial embodied energy, while the energy used in maintaining building over its active life is known as recurring or maintenance. In mathematical expression, embodied energy is the sum total of initial embodied energy and recurring energy, whereas initial embodied energy is the sum total of material embodied energy, site construction energy and transportation as represented by equation

EEi = EEM + EET + EEC (Equation 1)

Where; EEi = initial embodied energy, EEM = embodied energy of material (cradle – to – gate), EET = embodied energy of transportation (gate – to – site), EEC = site construction energy.

2.3. Operation Energy

Operation energy is one of the parameters for assessing sustainable buildings. The energy used in keeping the indoor environment within the acceptable range and other human activities is referred to as Operating energy [20]. Through the operational phase, that is when the building is fully occupied, energy sources such as electricity for appliances, air-conditioning, lighting; LNG (cooking gas); kerosene, PMS (petrol) and diesel for powering electricity

generators constitute the segment of energy called operating energy. Data for computations are often obtained using questionnaire and the questionnaire are distributed to occupants. Operations energy can vary depending on the level of luxury essential to occupants, the predominant climatic environments as well as the operational plan [10]. This underscores the much effort to improved building energy efficiency through lowering of operational energy. In the case study area, metering of energy is at the point of entry to the building. The energy expended by the occupants is referred to as delivered energy [25], while the energy that is embodied in resources as they are found in nature: chemical energy embodied in fossil fuels (coal, oil, and natural gas) is known as Primary energy. However, energy used during the operation of buildings is generally stated in primary energy terms which integrates the source of the energy being expended in its delivered state. Energy and Treloar [23] added that in computing operational energy, primary energy is a suitable measure of the environmental consequences of energy- use. Its equivalence is gotten by the multiplication delivered energy with the primary energy factor (PEF). The primary energy translation factors are determined by the electrical energy mix of the study area.

2.4. Demolition Energy

Whenever a building’s life span or service life comes to a close, the structure is decommissioned and carried to landfill sites [10] and some demolition procedures are often employed, these are; mechanical demolition, deconstruction and hybrid demolition. Decommissioning energy is energy required to demolish a structure at the expiration of its life time. In most cases, the outcome is not dependent on material choice [26]. There is the possibility that some materials at the demolition stage could be recycled into the materials fabrication stage. This results to some level of ambiguity at the demolition phase with regards to the outcome of building materials in the future [27]. Nevertheless, existing studies indicated that energy needed for demolition is about one percent (1%) of the whole life cycle energy [27-28].

2.5. Life Cycle Energy Assessment (LCEA) in Buildings

Assessing environmental sustainability in buildings is multifaceted. Reliable number of research work has gone into developing framework for assessing the environmental performance of buildings over its life [29]. Life-cycle energy analysis includes the operational energy of the building, initial and recurrent (maintenance) embodied energy throughout its life cycle [25]. Life-cycle energy analysis is express in equation 2:

LCEA = EEi + (EErec +OE) x Service Life equation (2)

where: LCEA = the life-cycle energy assessment;

EEi = the initial embodied energy;


EErec = the annual recurrent (maintenance) embodied energy; and

OE = the annual operational energy (air- cooling appliances, light fittings and domestic energy uses).

Haapio and Viitaniemi [30] stated that the period of time after installation, in the course of which all the properties surpass the least satisfactory level is known as service life. Existing studies revealed that the service life of a building is determined by Life Cycle Assessment goals. According to Holmess and Hudson [31] environmental sustainability assessment in buildings has developed as one of the key subjects in sustainable architectural design and building construction. Nevertheless, in the developing countries, measuring the environmental sustainability of buildings is comparatively new and it is largely based on the statements or sustainability declaration presented by the manufacturers [32]. Ding [29] added that these tools are fundamentally in two groups: Assessment Tools and Rating tools.

Sustainability assessment measures (environmental or performance-based) are continuously developing in order to overcome their several restrictions [33]. Nevertheless, two key assessment approaches that are notable: quantitative approach and qualitative assessment approach [34-35].

2.6. Application of LCEA in Buildings

LCEA is well-positioned to deliver quantitative data to building professionals because it holistically assesses the environmental impacts of a product [36]. The main aim of LCEA is to inspire teamwork involving professionals in the built environment and construction process. There are methods that have been developed to compute life cycle energy in buildings as fully and exactly as possible: process -based; input - output; and hybrid [25]. Process-based method was adopted for the case study and the unit of measurement are megajoule (MJ), gigajoule (GJ) or in tonnes of oil equivalent (toe).

Process-based assessment - This is carried out in four (4) stages namely: goal and scope definition; inventory analysis; impact assessment and interpretation. During the process indirect/direct upstream energy flows of a product or process is evaluated and quantified [10]. The material upstream energy flow consists of extraction, manufacturing, transportation, construction and use flows (use and maintenance), while the downstream flow includes deconstruction [37].

Input - Output Assessment - Makes use of national statistical information such as gross domestic product (GDP) and economic growth per-capita compiled by government agencies or ministries for assessing national economic growth and flows amongst sectors. According to Optis [38] the system boundary of the technique is more comprehensive than process-based LCA because it accommodates the various economic influences within the

economy. Nevertheless, the accuracy level is far lower than the process-based technique because of the level aggregation of industry classification lacks regional variances [39].

Hybrid Assessment - This is a combination of the merits of process-based analysis (dependable energy consumption figures for specific processes) and that of input-output analysis (theoretically complete system framework) while removing their characteristic weaknesses - incompleteness and mistakes. A study by [40- 41] in an Australian building revealed that hybrid assessment can be employed to advance the correctness of embodied energy assessment.

2.7. Application of LCEA and Architectural Design Process

LCEA can be applied at the various stages of design process; Pre-design stage, schematic design stage and detailed design or design development.

2.7.1. Pre-design stage This implies choosing the right systems and setting the

right environmental goals [36]. LCEA is critical at this stage to guarantee energy efficiency, since it governs how the building is properly incorporated with the immediate environment [9]. Interpretation of the results of an LCEA entails the design team to prioritize which environmental impacts categories are most significant to discourse. For instance, does the design team want to reduce carbon emissions through the use of carbon-sequestering products? And what is the cost implication? LCEA could be used to make decisions regarding selecting a structural system and the building footprint among numerous possibilities. Bayer, Gentry; Joshi & Gamble [42] added that at this stage operational phases can also be evaluated to decide assembly types. Passive design strategies such as building positioning and building forms are determined in this stage and could meaningfully influence the energy performance of buildings especially at the use stage. The outcome of LCEA at this stage will help the design team to consider “daylighting, natural ventilation and passive design solutions for heating and cooling, using mass, landscaping and design to work with topography and climate” [43- 44].

2.7.2. Schematic Design Stage At the schematic stage the design proposal approved by

the client is now taken to a more serious and detailed level. LCEA can help design team make choices regarding building products and optimize structural systems by selecting the most environmentally friendly options [45]. Energy conservation procedures such as active approaches for cooling and heating systems, motorized by renewable resources are evaluated for their environmental loads, and a well-versed decision can be enhanced by the use of LCEA [9,36,46]. Buffaloe and Rebecca 2014 stated that at the schematic design phase, LCEA reminds the design teams


to ask the questions: How much material does the project actually need? And what is the spatial arrangement of structural systems that hugely minimize the environmental impact of the project?

2.7.3. Detailed Design or Design Development Stage At this stage, the schematic design is worked through in

detail, detailed working drawings are produced for co-coordinating structure, services, and professional installation. LCEA can shed light on the environmental trade-offs of various product choices during specification writing. For example, if the architect chose a steel panel door over wooden panel doors during pre-design and adopted steel panel doors needed during schematic design, LCEA can assist the architect to compare the pros and cons of different door material selections. Material finishes and water fixtures choices could impact potable water conservation, hence, can also be compared with the help of LCEA results [9].

2.8. Examples of Life Cycle Energy Assessments

An appraisal of existing studies on LCEA of buildings shows that the outcomes were dependent on Life Cycle Assessment goals and these goals significantly influenced the boundary, approach and methodology.

In Scotland, Asif, Muneer& Kelley [47] assessed a semi-detached three (3) bedroom residential building. LCEA was employed to evaluate the material embodied energy and the consequences on the environments. In the study, 65% (227.46GJ) of the embodied energy of the referenced building and up to 99 % of the resultant environmental burden was attributed to concrete components. Chang, Reis &Wang [48] undertook an LCEA study using residential buildings in China. Interestingly, the study discovered that energy consumed

by rural house units were much lower than total energy use by urban house units. For both cases, the percentage of operational energy was higher ranging between 75 % - 86 % of total life cycle energy separately. Moreover, an Australian study, Myers, Fuller & Crawford [49] revealed that embodied energy can be reduced by 28% (7.5GJ/m2 to 5.4GJ/m2) by simply replacing conventional materials with renewable building materials. Mithraratne & Vale [50] carried out LCEA using a New Zealand residential building as a case study with the aim of assessing its energy-use under different conditions adopting 100 years as service life. The study shown that operational energy varied from 57% to 74% of total life cycle energy and using extra insulation decreased the life cycle energy by 31%. The above study concluded that concrete elements though has the highest initial embodied energy component possibly will possess a lengthier valuable life that might result to lower embodied energy at the long run.

2.9. Case Study

For easiness and understanding of the discussion, Life-Cycle Energy Assessment (Process-Based) is demonstrated using a residential building project located in Abakaliki, south eastern Nigeria. The residential building analyzed for a service life of 60 years is a block one-bedroom apartment building containing five (5) units designed by EDT/GEMEX architects and engineers in 1997 and built by Ebonyi state Housing development Corporation (EBSHDC), Abakaliki, Nigeria. A total of one hundred and sixty-five (165) house units were used as sample size each building has a gross floor area of 355.68m2 as shown in figure 3 with details in appendix 1, 2 and 3.


Figure 3. Typical Floor Plan of one (1) Bedroom house unit (details in appendix 1, 2 and 3) Source: ESHDC

3. Case Study Results Results obtained for the intensity for embodied energy,

operational energy and total life-cycle energy are stated in square meters (M2) rate founded on the livable area of 355.68m2, also referred to as energy intensity. This is to enable comparison with other results having different sizes and in this type of climate as obtained from other studies.

3.1. Embodied Energy

As presented in table 1, material embodied energy (cradle to gate) for the case study was calculated to be 1095.48 GJ and energy intensity of 3.08 GJ/m2, with superstructure having the highest energy intensity of 0.88GJ/m2. For transportation energy the estimated quantity of fuel consumption of 3,408.72 liters of diesel, multiplied by the 35.94 being the default heating value, the

energy for materials transportation was computed as 122.51GJ with energy intensity of 0.34GJ/m2. In computing the construction (Manual and Machine) it was observed that majority the construction events were carried out manually and few contractors had machine/equipment. Hence, contract sum /labour cost were obtained and manual energy computed using human energy coefficient of 0.75 MJ/hour with day-to-day working period of 8 hours. The human energy factor was obtained from the Nigerian Agricultural sector’s settings and effectively used in industrial situations by Odigboh [51] and Ohunakin, Leramo, Odunfa & Bafuwa [52]. Quantity of diesel, petrol and lubricant were obtained and the value was multiplied by their energy coefficient. The construction energy (manual and machine) was calculated to be 60.16GJ with construction energy intensity value of 0.169GJ/m2.


Table 1. Cradle – to – Gate Embodied Energy Computation. Source: Author

No Bldg Component Embodied Energy (MJ) Intensity (MJ/m2) (%)

1 Substructure 314,574.91 884.43 28.72

2 Walls 236,701.30 665.48 21.61

3 Roof Structure 205,298.86 577.20 18.74

4 Doors and Windows 58,158.72 163.51 5.31

5 Wall Finishes 57,253.31 160.97 5.23

6 Floor Finishes 38, 699.08 108.80 3.53

7 Ceiling Finishes 35,550.38 99.95 3.25

8 Painting and Decorations 64,453.80 181.21 5.88

9 Plumbing Installation 63,826.78 179.45 5.83

10 Electrical installations 20,958.67 59.93 1.91

TOTAL 1,095,475.8(1095.48GJ) 100

Table 2. Total Embodied Energy of the referenced building. Source: Author

No Embodied Energy Category Embodied Energy (MJ) Intensity (GJ/m2 ) (%)

1 Cradle-to-Gate 1,095,475.81 3.08 50.3

2 Transportation(surface) 122,509.36 0.34 5.6

3 Site Construction 60,160.82 0.17 2.8

4 Recurring Embodied Energy 892,318.41 2.51 41.0

TOTAL 2,170,450 (2,170.5GJ) 6.10 100

Table 3. Operational energy (Annual) of house unit of the case study building. Author

No Energy Source Monthly Consumption Annual Consumption

Lower Heating Value/Primary Energy

factor

Total Primary Energy (MJ)

1 LNG 2Kg 24Kg 47.3 1,135.20

2 Petrol 24.36liters 292.32liters 32.7 9,558.86

3 Kerosene 20.15liters 241.8liters 35.24 8,521.03

4 Diesel 0 0 35.94 0

5 Electricity 188.7kwh 2264.6kwh 2.83(3.6MJ) 23,071.59

Total 42,286.69(42.29GJ)

The initial embodied energy was calculated to be 1278GJ with energy intensity value of 3.60GJ/m2. Recurring energy was estimated using 60 years as service life and the estimated value is 892.3GJ while the recurring energy intensity was estimated as 2.51GJ/m2. Using equation 1, the total embodied was calculated as 2,170.45GJ as presented in table 2. The embodied energy intensity is calculated as 6.10 GJ/m2.

3.2. Operation Energy

Data for identified energy source (quantity of Petrol, Kerosene, Diesel and LNG) for calculating the operation energy were obtained from the questionnaire. The values obtained were multiplied by the respective heating values and primary energy factor in line with Intergovernmental Panel on Climate Change (IPCC) protocol. The annual operational energy was calculated as 42.29GJ, with annual operational energy intensity as 0.59 GJ/m2/year. Over 60 years (Service Life) the operational energy was estimated as 2,537GJ with operational energy intensity as 35.67GJ/m2 for a house unit.


3.3. Total Life Cycle Energy Assessment (LCEA)

Equation 2 was used to calculate the total LCE. Since the operation energy was computed based on house unit the value for embodied energy per house unit was calculated by dividing the total embodied energy value by five (5) being the number of house unit per block. The total embodied energy per house unit is calculated as 434.1GJ, while the operational energy is 2,537GJ. Thus, the Life Cycle Energy for the case study house unit is 2,971GJ. The embodied energy accounted for 15%, while operational accounted for 85% of the total Life Cycle Energy Assessment as shown in figure 4, and the LCEA intensity is given as 41.84GJ/m2 for a house unit.

Figure 4. Total Life Cycle Energy percentage distribution. Source: Author

4. Discussion The values obtained from the case study is comparable

with the existing studies. The Life Cycle Energy Assessment was computed as 2,971GJ. It was observed that cement base materials accounted for just 8.8% by mass of total concrete used, however, it contributed 67.6% of the total embodied energy. This is slightly higher than the value from the Scottish study – 65% [47]. The study is on the view that reducing concrete based element in buildings is a panacea for the reduction of embodied energy. The embodied energy intensity value of 6.10GJ/m2 for the study area is high in comparison with the mean of 0.663GJ/m2 in a study by Ghattas, Gregory, Olivetti & Greene [53]. An earlier Nigerian study reported 7.38GJ/m2 for a similar building in Lagos [10]. The value of embodied energy intensity of the study area and that reported by Ezema [10] are of great concern with regards to sustainable housing and hence requires urgent actions. With regards to operational energy, the value of 41.84GJ/m2 obtained in the study is higher than 27.3GJ/m2 – 31.68 GJ/m2 reported in a foremost LCA by Adalberth [54]. However, the value is lower than a similar Australian and Nigerian (Lagos) study which also adopted direct calculation from electricity bills, the studies reported operational energy intensity values of

86GJ [41] and 51.8 GJ [10]. Similarly, the value falls within the range values range of 37.3 GJ – 66.85 GJ/m2 presented by Ramesh, Prakash, Shukla [55]. The operational energy accounting for 85.4% for the study is higher than the values (57% - 74%) reported by Mithraratne and Vale [50]. In line with the study objectives, using energy intensity as a parameter and based on the values obtained from the study, it is evident that more enlightenment is urgently needed with regards to sustainable architecture and development of sustainability assessment framework that integrate local data instead of relying only on international data. Especially now that the developing countries are racing to mitigate the housing deficit. It is imperative to adopt more sustainable measures in design process and renewable energy alternatives in order to reduce operational energy in the housing sector. Also, integration of passive design styles at the early stages of the design process is one of the effective methods of reducing operational energy in buildings. Moreover, it is important to note that in the study area, kerosene and petrol consumption contributed significantly to operational energy in comparison with developed countries, with 20.15% and 22.60% respectively. This is as a result of inadequate grid electricity supply in the study area (this is very common in the developing countries) resulting to the use of electricity generators and kerosene lamps/cooking stoves by the occupants. This underlines the need to improve grid electricity supply in Nigeria as a way of aligning with the global quest for sustainable built environment.

4.1. Implications of the Findings

Understanding the energy-use consequences of architectural design is key to sustainable architecture and climate change mitigation/ adaptation strategy in the housing sector. Life Cycle Energy Assessment (LCEA) of the referenced building provided an opportunity to identify the implications of architectural design decisions and the various dimensions of sustainable architecture in practice.

There are policy implications of the research findings with regards to energy -use and energy intensity regulations in the national building code especially for new buildings. According to Okonjo-Iweala [56] the Federal Mortgage Bank of Nigeria put the country’s present housing deficit at 17-22 million, as a result, the Federal Government is currently constructing affordable homes in 34 states of the federation. Thus, in order to lessen the energy intensity resulting from mass housing, it is imperative that the climaxes in their embodied energy and operational energy are addressed. Cement based building materials accounting for 67.6% is of great concern, therefore, at research and development level, more research intended at finding alternative materials and substitute for cement in building construction needs to be encouraged. Moreover, GHG emissions and energy-use in


the housing sector should be given thoughtful deliberation in energy and CO2eq lessening plans, instead of focusing only on oil, gas and agricultural sector, especially now that efforts to reduce the housing deficit is gaining momentum from the informal and formal investors.

At the level of architectural education and practice, there is need to include environmental sustainability assessment protocol in school curriculum and workout synergy with appropriate regulatory institutions to regulate and certify alternative materials to enhance their specification by architects. This will make the vision 2050 of the International Union of Architect realizable.

One of the ways to reduce the operational energy in the study area is the adoption of renewable energy technology. Thus, policy should focus on how collections of housing units or housing estates can be stimulated to install integrated Photo Voltic (PV) retrofits including micro-grid renewable installations.

5. Conclusions According to Guy and Farmer [57] sustainable

architecture is not a ‘prescription’, but it’s an approach, practice and an attitude. The study reviewed the theoretical

challenges associated in defining what we mean by calling a building “green” or sustainable architectural design and provides a summary of a post-positivism viewpoint on the development of sustainable architecture by using a case study. The imperative of an architect having an all-inclusive knowledge of all aspects of sustainability in order to be able to engage with a variety of professionals and specialists underscores the significance of this paper. From sustainable architecture perspective, buildings and infrastructures should become producers of energy rather than being just consumers of energy, directing our attention to imagining a future where we give more than we take. From the values obtained from the study and existing Nigerian study shows that the embodied energy intensity of the Nigerian housing sector is high.

Architects need to take responsibility at the early stage of building design by carrying environmental sustainability assessment of their design. This is because no one can claim that his building design is sustainable until a Life Cycle Assessment is carried out. This calls for more enlightenment among architects in practice with regards to Life Cycle Energy Assessment and the use of architectural design strategies for climate change migration and adaptations.


Appendix 1: Floor Plan of one bedroom apartment at Udensi Estate, Abakaliki. Source: EBSHDC


Appendix 2: Section X-X of One (1) bedroom apartment at Udensi Estate, Abakaliki. Source: EBSHDC


Appendix 3: Approach View of One (1) bedroom apartment at Udensi Estate, Abakaliki. Source: EBSHDC

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Air Temperature Analysis of a Residential House Using Soliworks Flow Simulation

Estrella C. Macabutas1,2,*, Alejandro F. Tongco1

1Engineering Graduate Program, School of Engineering, University of San Carlos, Philippines 2College of Engineering and Technology, Western Philippines University, Philippines

Received July 6, 2020; Revised August 17, 2020; Accepted September 11, 2020

Cite This Paper in the following Citation Styles (a): [1] Estrella C. Macabutas, Alejandro F. Tongco , "Air Temperature Analysis of a Residential House Using Soliworks Flow Simulation," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 792 - 800, 2020. DOI: 10.13189/cea.2020.080506.

(b): Estrella C. Macabutas, Alejandro F. Tongco (2020). Air Temperature Analysis of a Residential House Using Soliworks Flow Simulation. Civil Engineering and Architecture, 8(5), 792 - 800. DOI: 10.13189/cea.2020.080506.


Abstract The model house under study is a typical house with a G.I. roofing but it was retrofitted by adding a green-material (bamboo) into, thereby forming a parallel plate air passage. The air, in passing this channel (airgap), undergoes a natural or free convection process of cooling. Buoyant forces cause this downward flow of cooled air through the airgap. The roofing airgap designed to direct this cooled air to the room to be ventilated. The flow through the airgap is laminar because of the low air velocity caused by the free-convection process of cooling. This study evaluated the performance of a house with roofing that was retrofitted with a type of green-material called bamboo. An evaluation applied to 88 square meters of space through air-temperature analysis. The tool used in this analysis was the FloEFD simulation software. The inputs required in setting up the FloEFD model are initial boundary conditions, ambient pressure and temperature, the estimated space heat load (assumed to be constant), and the roof module. Based on the results obtained, the indoor temperature depends on the boundary conditions or the outside environmental temperature. The indoor air temperature decreased an average of 2°C from outdoor temperature with the initial conditions of 31°C and room heat flux of 300 Watts/m2 with a resultant air movement inside the room ranging from 0.217 m/s to 0.651 m/s. The insulating property of green-material utilized in the roofing system was instrumental in lowering the airgap exit temperature by an average of 4°C.

Keywords Air Temperature, FloEFD, Residential House, Roof, Simulation

1. IntroductionIn countries located in the tropics such as the Philippines,

ventilation and cooling are necessity to sustain the thermal comfort of occupants. Due to the rise in energy cost, this passive cooling method may prove to help alleviate the situation. The idea of passive cooling (passive heating in cold countries) entails the inclusion of passive design concepts in the pre-construction activities by designers.

Many studies on the passive cooling of buildings carried out using the simulation approach. The simulation method has high levels of accuracy [1]. There are buildings that require better circulation air to maintain low-temperature air with high relative humidity [2]. As stated by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), thermal comfort is “a condition of the mind in which satisfaction expressed with the thermal environment” [3]. The psychrometric process that occurs in the airgap is a sensible cooling one, and thus, the relative humidity increased while maintaining the constant moisture content of the air. The psychrometric process that the air went through in the airgap is sensible cooling. The study here centered on the structure with airgap integral to the house. The analyses and corresponding evaluations were carried out considering the effects of the mixing of cooled air from the airgap to the room air initially at a temperature equal to boundary conditions.


Solidworks flow simulation is the thermal analysis that deals with heat transfer to predict air-temperature changes [4] and evaluate the system for temperature and fluid flow that could help designers and Engineers [5]. Using the numerical approach, the building can be designed to alter the condition of temperature and airflow to some extent [6].

The Philippines is fast becoming a highly urbanized country with many establishments such as restaurants, hotels, shopping malls, amenities, and modern houses. In the fast-growing cities, modern housing-built condominiums, apartments, dormitories, or bungalow–type residential houses. The energy demand for cooling is constantly on the rise due to the fast-increasing rate of occupancy. Typical houses in urban areas have uncomfortable space temperatures [7]. Passive cooling may drastically alter the conceptual designs of houses and buildings, providing in-built features to attain low indoor temperatures. Not only in residential houses but also commercial buildings that depend on mechanical ventilation systems may avail of passive cooling concepts to attain lower indoor air temperatures, employing hybrid systems for reasons of the economy [8]. The continued usage of a stand-alone window-type air-conditioning system can lead to respiratory problems of building occupants as they provide an almost 100 % recirculated air [9]. Contrary to this, passive cooling systems provide almost 100% fresh outside air.

This study can contribute to the growing needs for the low-temperature, high-quality thermal environment by taking advantage of the natural phenomena around us. In addition to this, the research study entails the use of a locally-sourced green-material, preferably with high insulation value. Simulation and analysis were carried out employing Solidworks flow simulation driven by FloEFD. The results presented in this work can provide a reference to the currently applied thermal comfort analysis, especially to residential houses in the tropics. The input to this study is boundary conditions (26°C, 27°C, 28°C, 29°C, and 30°C). Relative humidity at the boundary conditions is always assumed here to be constant.

2. Materials and Methods

2.1. Model Description

The modeled residential house consisting of corrugated G.I. sheet, airgap, insulation, and ceiling board made of green materials (bamboo), as proposed in this study is shown in Figure 1.

Figure 1 describes the corrugated roof (G.I. sheet, 12mm) having a low pitch (or slope) of 2/12 (approximately 9.5 degrees). The peak of the roof joins a vertical wall with an airgap underneath to represent a tilted channel formed between two parallel plates. Warm air circulates through the interior of the house, flows through the 30.48 cm-deep

airgap, giving its heat to the roofing and flows downward at extremely low rates. Because of the depth of the airgap, the natural convection is somewhat suppressed, and the heat transfer is assumed to be by conduction alone. The warm air at airgap losses some of its heat to the G.I. sheet. The sky and the ambient air serve as the heat sink for the system while the massive construction of the room’s concrete walls stores sensible cooling to reduce space conditioning needs. The insulation and ceiling isolate the air in the airgap from the warm room air.

The boundary conditions used for the simulation are: Boundary (box); 24.36 (m) x 15.72 (m) x 12.16 (m); Environmental pressure: 101,325 (Pa); Heat sources: 300 (W/m2); Initial condition: 31(°C); Ambient (outdoor) temperature: 26 (°C) – 30 (°C); and Radiative surfaces: roof, outside wall, heat sources.

Figure 1. FloEFD model of the residential house

2.2. Simulation Tool

In this study, the FloEFD simulation tool used to assess the system’s performance in terms of resultant temperatures before and after the mixing of the cooled air and the initially warm room air. Parameters used to simulate the indoor temperature at different nodes. A Solidworks simulation tool driven by FloEFD used to perform simulation works. Solidworks incorporated in the software for the creation of 3D models.

The roof materials, initial boundary conditions of air and surface temperatures, and the heat load are the inputs to the FloEFD model. The model assumed leak-free space conditions for FloEFD analysis. It also assumed that laminar flow of air at the airgap and inside the room. The relative humidity level of 50%, the solar radiation, and heat conduction in solids were intentionally neglected for the purpose of simplicity. The influence of gravity and the increase in the density of cooled air were taken into consideration as the main heat transfer mode in the simulation of convection. The air pressure assumed was one (1) atmosphere (101,325 kPa). The concept of FloEFD simulation is shown in Figure 2.

794 Air Temperature Analysis of a Residential House Using Soliworks Flow Simulation

.

Figure 2. Concept of FloEFD tool for residential house building

2.3. Analysis of Results

The operative temperature concept such as GG average fluid temperature (Outside temperature of the house) SG average fluid temperature (outer and inner surface of the roof, an outer surface of the insulation layer, an inner surface of the insulation, an outer surface of ceiling board, and the inner surface of ceiling board), surface average wall temperature, room air temperature, the temperature of the heater, and relative humidity were used to analyze the simulation outcomes. The indices were calculated using an Excel spreadsheet that incorporates the computer program codes for estimation [10].


3.1. Simulation Tool

The FloEFD model simulates a typical residential house with a G.I. roof material that was retrofitted by adding a green material's insulation under it to form a parallel plate channel. The air contained in this channel (herein referred to as “airgap”) upon being cooled is convected down through the said airgap providing the room or space the needed ventilating airflow. It is then simulated for 300 Watts per square meter only (including the occupants). To

retain the thermal comfort inside the room without air-conditioned depends on the environmental temperature and boundary condition.

It was assumed that the environmental pressure was 101, 325 kPa (1 atm.) and Relative Humidity of 50%. The initial condition of 31°C for the outside wall whereas the environmental temperature and initial solid temperature assigned from 26°C to 30°C. This is the internal analysis type with considered close cavities. The heat transferred focused on conduction, convection, and radiation. The radiative surfaces are the roof, outside wall, and the heat source. The materials used for typical residential houses are GI roofing, green materials for insulation and ceiling board, and concrete materials for the walls.

Figure 3 demonstrates a boundary condition of 26°C. The resultant air and surface temperature of the inner room was 24.6°C and 27.93°C. The temperature of the air exiting the airgap is 22.2°C whereas the inner roof temperature was 22.24°C. The inner and outer insulation temperatures below the airgap are 21.57°C and 21.47°C respectively. The inner and outer ceilings attached to the insulation layer are temperatures of 21.57°C and 21.69°C, respectively. The temperature of the surface walls inside the room increased by 7% on the average from the input boundary condition. Thermal cooling of the room’s interior was obtained despite the approximated the room heat load of 300 W/m2.


Figure 3. Simulated temperature for the boundary condition of 26°C


The boundary condition in Figure 4 is 27°C with corresponding results of room and wall surface temperature of 25.46°C and 28.78°C, respectively. There are 23.26°C and 23.27°C for the airgap and the inner roof. While the temperature for the insulation layer of 22.47°C (outer) and 22.58°C (inner) and the outer ceiling is the same with the inner insulation but the outer insulation 22.69°C.

Figures 5 to 7 from the boundary condition of 28°C to 30°C. Initially, the inner surface wall temperatures of the room at the input boundary conditions were 29.80°C, 30.60°C, and 31.44°C. For the assumed boundary

condition of 28°C, 29°C, and 30°C, the resulting air temperatures entering the airgap were 26.49°C, 27.30°C, and 28.15°C, respectively. The fluid temperature from the airgap is about 24.19°C, 24.92°C, and 25.64°C, and the inner roof is around 24.20°C, 24.93°C, and 25.65°C almost the same with the airgap temperature. The outer temperatures of the insulation are 23.46°C, 24.12°C, and 24.84°C while the inner are 23.56°C, 24.23°C, and 24.95°C. Then the inner temperature of the insulation is the same as the inner temperature of the ceiling, however, the outer ceiling temperatures are 23.68°C, 24.35°C, and 25.07°C.




Figure 8 and Table 1 show the result of the simulated boundary condition assigned from 26°C to 30°C. The temperature of the surface wall of the house increases was ranged from 5% to 7% to the environmental temperature as shown in Figure 3 to 7. However, the fluid temperature that flows inside the house decreases from 1.3°C to 1.9°C from the assigned boundary condition. As you can see, the decreasing temperature of the house depends on the heat inside the room. If the heat lowers than of 300 W/m2 and the area of 88 square meters of residential house, there are possible the more decreases of the temperature inside the house. The roof module considered aiding for thermal

comfort cooling despite the approximated heat inside the room is 300W/m2 and the initial condition of 31°C.

Figure 9 shows the result of simulated air temperature and relative humidity. As you can see in the figure, the relative humidity ranged from 56.25% to 57.22%. This relative humidity was decreased although the air temperature inside the house decreases from the outside environmental temperature of 26°C to 30°C with the initial condition of 31°C. This is the process of mixing of air at constant humidity ratio resulting in a lower temperature but with increased in relative humidity.



Figure 8. Simulated temperature for the boundary condition from 26°C to 30°C

Table 1. Summary of results of simulated temperature based on the boundary condition from 26°C to 30°C

BC (°C)

Tr (o) (°C)

Tr (i) (°C)

Ta (°C)

Tm (o) (°C)

Tm (i) (°C)

Tp (i) (°C)

Tp (o) (°C)

Tc (i) (°C)

Tf (i) (°C)

Th (°C)

26 26.00 22.24 22.22 21.47 21.57 21.57 21.69 27.93 24.60 41.75

27 27.00 23.27 23.26 22.47 22.58 22.58 22.69 28.78 25.46 42.51

28 28.00 24.20 24.19 23.46 23.57 23.57 23.68 29.80 26.49 43.43

29 29.00 24.93 24.92 24.12 24.23 24.23 24.35 30.60 27.30 44.26

30 30.00 25.65 25.64 24.84 24.95 24.95 25.07 31.44 28.15 45.13


Figure 9. Simulated air temperature and relative humidity for the boundary condition from 26°C to 30°C

Figure 10. Air temperature with a boundary condition contours on the xy plane (26°C environmental temp) under 300W/m2 heat inside the residential house: (a) cut plot 1, (b) cut plot 2, (c) cut plot 3, (d) cut plot 4, (e) cut plot 5, (f) cut plot 6


Figure 11. Velocity with a boundary condition contours on the xy plane (26°C environmental temp) under 300W/m2 heat inside the residential house: (a) cut plot 1, (b) cut plot 2, (c) cut plot 3, (d) cut plot 4, (e) cut plot 5, and (f) cut plot 6

Figure 10 shows the result of a simulated boundary condition at 26°C with the initial condition of 31°C of different cut plots. In Fig. 10-a and 10-d, are the cut plot shows the front and back view orientation that the air temperature of the holes at the ceiling direct to the airgap. There is a flow of air temperature around 24°C to 27°C. However, the flow is different because of the windows, door, and the flow of the air from the airgap. In Fig. 10-b is the cut plot of 1.5 meters above the ground in the top view orientation. This figure shows the flow of air temperature of less than 27°C. This cut plot (Fig 10-b) is the temperature that made of the comfort inside the house although the air temperature of the ground higher because of the heat start from the ground then moved upward through the airgap. The cut plot of the airgap as shown in Fig. 10-c for the top view orientation, there is a flow of air temperature around 4 holes in every corner. The air temperature of the airgap is less than 26°C because the flow of heat goes up that merge in the air-cooled container

(airgap). In Figure 10-e and 10-f are the cut plots of the middle of the house with different orientations. Fig. 10-e is the right view orientation almost the same with the flow of left view (Fig. 10-f) where the air temperature is less than 26°C.

Figure 11 shows the result of the simulated flow velocity at different orientations at outer surface temperature of 26°C and with an ambient condition of 31°C. This Figure shows the different cut plots to determine the condition of air velocity inside the house. The higher air velocity was found in the two holes at the ceiling in a downward direction and measured between 0.58 m/s to 0.65 m/s as shown in Fig 11-a and 11-d. Most of the areas were found of a higher air velocity of 1.5 meters above the ground (Fig. 11-b). However, the higher air velocity at the airgap was also found at the 4 holes of the airgap (Fig. 11-c). In the cut plot (e) is the same situation of air velocity of a cut plot (f). Generally, the higher velocity was found in the four corners of the house which may be due to the holes were placed in


which the flow of circulated air at the airgap.

4. Conclusions The Solidworks software driven by FloEFD simulation

was used to analyze the air temperature of a typical residential house with the roof module made of locally sourced green material. To evaluate the air temperature of the residential house the boundary conditions were applied. The simulation results demonstrate the satisfactory uniform velocity and temperature distributions in the occupied region of the house. The results also indicated that analyzing the temperature distributions in the built system with EFD. The thermal EFD simulation model in this study incorporates the latest laminar modeling advancements applicable for room airflow simulation. It resolves the room’s air temperature distribution, and predicts air movement. It is found that the simulation outputs can give accurate numerical details of the secondary data such as relative humidity, and air movements.

Referring to the data plot the simulated results as shown for different ambient temperatures around the house would have lower surface temperatures. It was observed that the the airgap at exit has the lowest temperature record. The mean values for the air temperatures at the outside surface of the house were 26°C, 27°C, 28°C, 29°C, and 30°C at 300W/m2, average room air temperatures of 24.60°C, 25.46°C, 26.49°C, 27.30°C, and 28.15°C, respectively with an average decrease 2C°. The air velocity inside the room ranges from 0.217 to 0.651 m/s. This indicates that the local green materials were instrumental in the lowering of the supply air temperature by 4 C°. The materials used in the roof modules were local green material as insulation and ceiling board.

Acknowledgements The authors would like to thank to the National Taiwan

University of Science and Technology (NTUST), Taipei, Taiwan for granted the research internship program. Furthermore, the authors also acknowledge the Department

of Science and Technology – Engineering Research and Development Technology (DOST-ERDT), Philippines for graduate scholarship funding.

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[3] ANSI/ASHRAE, “ANSI/ASHRAE 55: 2004 Thermal Environment Conditions for Human Occupancy,” Ashrae, vol. 2004, p 30, 2004.

[4] P. Kurowski. Thermal analysis with Solidworks Simulation 2015 and Flow Simulation 2015. SDC publications, 2015.

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[9] A. Aflaki, K. Hirbodi, N. Mahyuddin, M. Yaghoubi, M. Esfandiari. Improving the air change rate in high-rise buildings through a transom ventilation panel: A case study. Building and Environment, 147, 35-49, 2019.

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DOI: 10.13189/cea.2020.080507

An Alternative Approach in Assessing Visual Comfort

Based on Students' Perceptions in Daylit Classrooms

in the Tropics

Irnawaty Idrus1,*, Ramli Rahim2, Baharuddin Hamzah2, Nurul Jamala2

1Doctoral Student of Department of Architecture, Faculty of Engineering, Hasanuddin University, Indonesia 2Laboratory of Building Science and Technology, Department of Architecture, Faculty of Engineering, Hasanuddin University,

Indonesia



(a): [1] Irnawaty Idrus, Ramli Rahim, Baharuddin Hamzah, Nurul Jamala , "An Alternative Approach in Assessing

Visual Comfort Based on Students' Perceptions in Daylit Classrooms in the Tropics," Civil Engineering and Architecture,

Vol. 8, No.5, pp. 801 - 813, 2020. DOI: 10.13189/cea.2020.080507.

(b): Irnawaty Idrus, Ramli Rahim, Baharuddin Hamzah, Nurul Jamala (2020). An Alternative Approach in Assessing

Visual Comfort Based on Students' Perceptions in Daylit Classrooms in the Tropics. Civil Engineering and Architecture,

8(5), 801 - 813. DOI: 10.13189/cea.2020.080507.


Abstract Daylight is the best lighting source for

classrooms that are mostly used during the daytime.

Effectiveness and productivity can be achieved if visual

comfort meets the recommendations set. This study aims to

develop an alternative visual comfort assessments method

based on students' perceptions in the classroom with

daylight. The study was carried out by collecting students'

perceptions and daylight illuminance data from 25

classrooms located in seven schools in Makassar,

Indonesia. A total of 737 students responded to this study.

This research was conducted from morning to noon in each

school. The results showed that the majority of students, as

many as 57.5%, felt that the level of daylight was

"Perceptible", and only 6.5% felt it was "Intolerable". The

results of daylight intensity measurements of 25 classes

showed that only 28% of classes meet the minimum

standard of the Indonesian National Standard (SNI), and as

many as 82% of classes do not meet the standard. Using a

new method based on student perception, it was concluded

that as many as 28% of classes were categorized as

"Acceptable", as many as 48% of classes were categorized

as "Preferred," and around 24% were not included in either

category. This shows that there are classes that are not in

accordance with recommendations, but are still acceptable

according to students' perceptions. This new assessment

method can be an alternative addition for designers to

assess the comfort of a room with daylight by users'

preferences.

Keywords Visual Comfort, Daylight, Classroom,

Students' Perceptions

1. Introduction

Many previous studies have explained that natural

lighting is the best source of light for buildings because it

has many benefits. Natural light helps create a healthy,

comfortable, and productive environment [1, 2]. In

addition, the use of significant natural light in buildings has

the potential to save 15-19% of electricity cost for lighting

[3, 4]. Architecturally, natural light is also useful for

creating dramatic design elements that provide a deep

visual experience [5].

However, natural lighting can only be used optimally if

there is enough sunlight in the area [5]. According to

Baharuddin and Ishak, Makassar city has great potential for

utilizing sunlight [6]. A Research by Rahim et al. showed

that, in June 2010, the value of global illuminance

measured in Makassar reached 142 kilolux [7, 8]. This

could be due to its location in a tropical area. This global

802 An Alternative Approach in Assessing Visual Comfort Based on

Students' Perceptions in Daylit Classrooms in the Tropics

illuminance is higher than the region located in

sub-tropical areas, e.g., Hong Kong, which has a maximum

global illuminance of 125 kilolux [8]. The tropical zone

extends from latitude 10° to 23°. Due to its geographical

proximity to the equator, it has an annual dry season during

all months. The sunshine in the tropics is available all year

round. Subtropics extend a further 10° towards higher

latitudes to about 35° North and South, and, in these areas,

the dry winters extend to about eight months of the year [9].

Natural lighting is highly recommended for educational

buildings [10]. Over the years, natural lighting has been

one of the most important factors in school design rather

than in other building designs [11]. Some researchers have

suggested the positive impact of natural lighting on user

performance [12], creating a pleasant environment [13],

creating a healthy environment [14], and supporting the

creation of sustainable building designs [15].

The fact that students spend as much as 30% of their

time studying at school is a reason for the importance of

visual comfort in a school building [16]. Sunlight can have

both positive and negative effects on visual comfort

because of its dynamic nature. It has an important role in

creating comfort in space [17]. Daylight can also affect

performance in reading and completing assignments, and it

can also affect the students' moods, emotions, and behavior

[18].

Visual comfort is influenced by various interrelated

factors. Existing metrics only evaluate one variable at a

time; therefore, no index has been defined which can be

considered as a parameter to represent the visual

environment. To compare buildings or building variants, a

percentage index is usually preferred, because it does not

depend on the absolute magnitude of the phenomenon

involved. In addition, individual values allow for easier

data comparison and interpretation, and more effective

interpretation of results [19].

This paper discusses visual assessment of comfort in

classrooms based on students' perceptions. In this study,

the authors aim to develop dynamic metrics based on user

perceptions to assess students' visual comfort by asking

several questions that refer to Spatial Daylight Autonomy

(sDA) and Annual Sunlight Exposure (ASE). The

questions will illustrate several factors that influence visual

comfort, such as the amount of light, uniformity of light,

quality of light, and glare according to students'

perceptions. The method is an alternative approach in

assessing visual comfort in classroom during daylight. A

more comforting environment will support student

performance in learning. Learning environment is an

essential key factor in determining the academic

achievement of students [20].


Many researchers around the world initially assess

visual discomfort based on the level of glare, independent

of personal preferences. Guth, who introduced the Glare

Index in 1949 [21] and others compiled a visual discomfort

assessment formula by predicting the level of glare. In

1972, Hopkinson formulated The Daylight Glare Index

(DGI or Cornell Equation) [22]. This was followed by

introduction of the CIE Glare Index (CGI) by Einhorn in

1979 [23]. This CGI was later refined by the Commission

Internationale de l'Eclairage in 1995 with the formulation

of The Unified Glare Rating System (UGR) [24]. In 2001,

Nazzal developed the New Daylight Glare Index (DGIN),

which is a modification of Hopkinson's original equation

that introduces several new variables into the metric [25].

All of these methods show correlations between light

sources and potential glare, but glare is a complex

phenomenon, and the assessment of glare will be different

for each observer.

After a few years, methods to assess glare were

enchanced to include user glare preferences. Harrold and

others proposed the concepts and formulas of Visual

Comfort Probability (VCP) [26]; Wienold &

Christoffersen [27] developed Daylight Glare Probability

(DGP) calculated by glare in vertical illumination. Hirning

[28] validated previous glare measurements and introduced

the Unified Glare Probability (UGP) as a predictor of glare

discomfort, by using a combination of natural lighting

mapping and user questionnaires [29]. Several studies on

visual comfort involving user questionnaires have been

conducted, such as by Chinazzo, which concluded that no

significant differences in evaluation of visual perception

were found between the moderate and high levels of

daylight, especially in terms of visual comfort [30].

Korsavi's research determined that daylight and sunlight

areas are no necessarily based on students' perceptions, and

concluded that these areas do not always cause visual

discomfort [31]. Methods involving user preferences will

certainly show a strong correlation with the perception of

glare, but glare is not the only factor that can cause visual

discomfort in daylighting spaces. Several metrics related to

natural lighting should be examined to find new, more

complex approaches to visual comfort.

Some important aspects that are considered in natural

lighting include the amount of daylight, personal

satisfaction, and energy conservation. To assess various

aspects of the day, experts use primarily dynamic as

opposed to static metrics [32]. Several studies have

revealed the advantages of dynamic metrics compared to

static metrics [33, 34]. Dynamic metrics take into account

daily and seasonal changes in natural lighting [35], which

static metrics do not consider. Static metrics also do not

account for user convenience [36]. Therefore, dynamic

metrics are also referred to as climate-based metrics [36].

Climate-Based Daylight Modeling (CBDM) is a new

approach approved by IES for daytime evaluation, based

on two metrics based on daytime conditions of a typical

meteorological year (TMY): Spatial Daylight Autonomy

(sDA) and Annual Sunlight Exposure (ASE) (IES LM

83-12) [37]. Spatial Daylight Autonomy (sDA) measures


the adequacy of daylighting for a particular area; this is

defined as the percentage of floor area, which meets or

exceeds the specified lighting level (300 lux recommended

on a horizontal surface, 0.8m above the finished floor) for a

certain number of annual hours (recommendation: 50% of

hours from 8 am to 6 pm). IES recommends two different

levels of quality for Spatial Daylight Autonomy; if 75% or

more of the analysis area meets the criteria categorized as

"Preferred", and if 55% or more of the analysis area meets

the criteria categorized as "Acceptable" [38]. Spatial

Daylight Autonomy is a comprehensive performance

metric combining time and space, which can be more

easily understood. Annual Sunlight Exposure (ASE)

assesses the potential for visual discomfort caused by

direct sunlight in the work area (lighting value indicator >

= 1000 lux). ASE is defined as a percentage of the analysis

area that exceeds 1000 lux for more than 250 hours per

year without using blinds and assuming operational time

between 8a.m. to 6p.m. [39, 40]. All of the aforementioned

metrics and assessment methods have their respective

advantages and disadvantages. Fundamentally, all of these

visual comfort metrics can complement each other.

Previous assessment methods formulated by researchers

have not included user perception as a measure of visual

comfort. Based on this, an alternative approach to

assessing visual comfort based on user perceptions could

further complement existing assessment methods.


3.1. Methodological Framework

The methodology essentially includes three stages. In

the first stage, the object of research is the level of natural

lighting in classrooms. Data was collected using

measurement tools, and then analyzed for suitability with

the classroom minimum lighting rules defined by the

Indonesian National Standard (SNI). At this stage,

supporting data is collected, such as the geometry of the

classroom, the size of light openings, the orientation of the

class, weather conditions, and the situations around the

research object.

In the second stage, the object of research is the

perception of students' visual comfort in a classroom with

natural lighting. Data collection for the first and second

stages was carried out simultaneously. Student perception

data was obtained using a questionnaire. The questionnaire

contained the respondent's information, date and time of

measurement, sitting position, class orientation, sky

condition, and questions regarding visual comfort

perception. Respondents answered each number according

to the instructions of the researcher. Before students

answered questions, researchers first provided an

understanding of the purpose of the questions to be

answered, so students would understand the purpose of the

question. Technical terms such as "overall sensation of

visual comfort" and "glare" are explained to students in

easy-to-understand language. In addition, to help

researchers achieve the research objectives, the selected

respondents were of age ten years and over.

Student perception is measured through a questionnaire

consisting of four questions. The student questionnaire

uses a Likert scale, which consists of five answer choices.

The first and second questions are 'students' impressions

about daylight availability and uniformity (sDA-related

questions), and the third and fourth questions are 'students'

impressions about sunlight (ASE-related questions) [31].

Both of these metrics are dynamic metrics, that are also

referred to as Climate-Based Daylight Modeling (CBDM).

The first question asks about perception of the availability

of daylight (DA) at the student's desk. The question

showed students' perceptions about the adequacy of light

perceived in their respective places. The second question

asks about the perception of daylight uniformity (DU)

throughout the classroom, showing students' perceptions

of the adequacy of light felt throughout the classroom.

The third question about Sunlight Comfort (SC) asks

about students' opinions of direct sunlight entering the

class. The fourth question about Perception of Glare (GP),

asks about students' perceptions of the glare felt in the

classroom. Students chose their answers according to their

feelings about the daylight condition. The last question

asks about conclusions about the overall sensation of

visual comfort felt. The answers from students also

indicated the percentage of perceived daylight comfort in

class. The data was analyzed using the descriptive

analysis method.

In the third stage, the object of research is the visual

comfort of the classroom. At this stage, the classroom is

assessed using the proposed method. The data that has

been obtained in the second stage is reanalyzed by this

method. Before determining the variables used to assess

the visual comfort of the classroom, Pearson's bivariate

correlation statistics are held first on the Questionnaire

Question. The proposed assessment formula is adopted

from the Spatial Daylight Autonomy (sDA) metric.

3.2. Research Location and Respondents

There are 25 classes in the research sample, located in

seven schools consisting of elementary, junior, and senior

high schools in Makassar City, Indonesia. The object of

research is public schools owned by the government.

Government-owned schools were chosen because they

have similar classroom dimensions, but differ in the

openness model and size. Three to five classes are chosen

for each school to be the object of research, with

North-South and East-West orientations. Details of the

research object can be seen in Table 1.

The assessment data was obtained from a questionnaire

filled out by students. A total of 737 students responded to

this study. In elementary school, only classes that are



occupied by students in the year of four, five, or six are

selected. For junior high schools, classes are selected for all

levels, and also for senior high schools. The age of

respondents ranges from 10 to 16 years old. All

participants had a normal or correct-to-normal vision.

Details of the respondents are presented in Table 2.

3.3. Data Collection Method

Data on daylight comfort perception was obtained

through a questionnaire that was distributed to students.

Data was collected in the classroom for 30 to 49 minutes

in each class. This research was conducted from morning

until noon. During the study, all the curtains were opened

and only natural light was used as a source of classroom

lighting. All electric lights were turned off. Students

answer the questionnaire from their numbered position.

The pattern of numbering student positions can be seen in

Figure 1(a). While filling out the questionnaire, the light

intensity data was taken using the Digital Lux Meter and

HOBO Data Logger measurement tools; the HOBO

device is equipped with an external sensor which can

function to measure temperature, light intensity, and

humidity [41]. In addition, measurements of the

classroom's dimensions include the length, width, and

height of the classroom using Krisbow digital distance

meters. The opening's dimensions measurement are carried

out using a manual distance meter. The placement of the

measuring instrument and the measuring point can be seen

in Figure 1(b). Placement of measuring points is regulated

based on SNI 03-2396-2001, consisting of two main

measuring points (TUU-1 and TUU-2) and four side

measuring points (TUS-1, TUS-2, TUS-3, and TUS-4).

The location of the TUU is 1/3d (from the field of the

effective light wall), and TUS is 0.5 meters from the side

wall [42]. The specifications of the measurement tools can

be seen in Table 3.

Table 1. Characteristic of Classrooms

Grade School Name Class

Code

Room Dimension (length x

width x height in m) Opening dimension (m2) Opening Orientation

Elementary

School

SD Ujung

Pandang Baru 1

1 7.5 x 7 x 3 12.66 E/W

2 7.5 x 7 x 3 12.66 E/W

3 7.5 x 7 x 3 12.66 E/W

SD Daya 1

22 7.5 x 7 x 2.8 12.52 E/W

23 7.5 x 7 x 2.8 12.52 E/W

24 7.5 x 7 x 2.8 12.52 E/W

25 7.5 x 7 x 2.8 12.52 E/W

Junior High

School

SMPN 29

9 9 x 7 x 3.3 24.08 N/S

10 9 x 7 x 3.3 28.28 N/S

11 9 x 7 x 3.3 18.2 N/S

12 9 x 7 x 3.3 24.08 N/S

SMPN 10

19 9 x 7 x 3.3 28.7 N/S

20 9 x 7 x 3.3 10.32 N/S

21 9 x 7 x 3.3 28.7 N/S

Senior High

School

SMAN 4

4 9 x 8 x 3.8 23.52 E/W

5 9 x 8 x 3.8 18.9 E/W

6 9 x 8 x 3.8 13.3 E/W

7 9 x 8 x 3.8 14.28 E/W

8 9 x 8 x 3.8 16.8 E/W

SMAN 2

13 9 x 8 x 3.0 19.6 N/S

14 9 x 8 x 3.0 19.6 E/W

15 9 x 8 x 3.0 19.6 E/W

SMAN 21

16 9 x 8 x 3.7 21.63 E/W

17 9 x 8 x 3.7 21.63 N/S

18 9 x 8 x 3.7 21.63 N/S

Table 2. Characteristic of Respondent

School Boy Girl Age (Year) Total

Elementary 89 99 10-13 188

Junior High School 94 130 12-14 224

Senior High School 129 196 14-16 325

Total 312 425 - 737


Table 3. Specification of Measurement Tools

No. Instrumen Name Range Accuracy Resolution

1 HOBO Data Logger Temp/RH/Light/External

(U12-012)

- Air Temperature -20 to +70 oC ± 0.21 oC 0.03 oC at 25 oC

- Relative Humidity 5 to 95% ± 2.5% 0.03 RH

- Lighting Intensity 11-32292 Lux NA (indoor use) NA (indoor use)

2 Digital Lux Meter

- Lighting Intensity 0.1-200000 Lux ± 4% 0.1 Lux

3 Krisbow, Laser Distance Meter 40 m NA

NA= Not Available

(a)

(b)

Figure 1. (a) Numbering of Student Position; (b) The Measurement Point



3.4. Data Analysis Method

The data obtained were analyzed using SPSS statistical

software and Microsoft Excel. Data analysis was carried

out in several stages, including:

3.4.1. Data Entry

All data obtained in the field is inputted into SPSS. The

variables are the student’s name, age, gender, eye

conditions, weather conditions, date, time, school name,

grades, sitting positions, daylight intensity, opening area,

DA perception, DU perception, SC perception, GP

perception and also the classroom orientation. According

to Jamala, the orientation variable affects the distribution

of sunlight [43].

3.4.2. Descriptive Statistical Analyses

Student perception data is grouped by each class..

Descriptive statistical analysis was performed on the

variables of DA perception, DU perception, SC perception,

and GP perception using SPSS. The visual comfort value

of students generated in five levels of perception, namely

Intolerable (I), Disturbing (D), Perceptible (P),

Comfortable (Cf), and Very Comfortable (VCf). The

student's comfort value is presented as a percentage.

3.4.3. Analyses of Students' Perception

The student comfort value is included in a table in Excel

format, like the example in Table 5. After inputting the data

in the table, the results obtained, which shows the

percentage of students' visual comfort perception in a

classroom.

3.4.4. Assessing the Daylight Comfort of Classroom

To assess the visual comfort of daylight in the classroom,

an assessment method was used based on student

preferences. Before determining the factors that most

influence visual comfort, a statistical correlation analysis is

performed. Students' questionnaire answers were analyzed

using an assessment method called Probability of Daylight

Comfort (i-DCP). This method was adapted from the

Spatial Daylight Availability (sDA) assessment. IES

recommends two different levels of quality for Spatial

Daylight Autonomy, and the first is if 75% or more of the

analysis area meets the criteria categorized as "Preferred",

the second is if 55% or more of the analysis area meets the

criteria categorized as "Acceptable".

This method assessed a room based on user preferences

of whether its daylight comfort is "Acceptable" or

"Preferred". Assessment results in two-tailed categories.

1st Category: “ACCEPTABLE” if (P+Cf+VCf)>=55% (1)

2nd Category: “PREFERRED” if: (P+Cf+VCf)>=75% (2)

Abbreviation note.

sDA : Spatial Daylight Autonomy

ASE : Annual Sunlight Exposure

DA : Daylight Availability on Desk

DU : Overall Daylight Uniformity

SC : Sunlight Comfort

CBDM : Climate Based Daylight Modelling

GP : Perception of Glare

I : Intolerable

D : Disturbing

P : Perceptible

Cf : Comfortable

VCf : Very Comfortable

4. Results

4.1. Daylight Intensity of Classrooms

Data collection was conducted from July to August 2019.

The weather conditions were mostly sunny at the time of

data collection. The light intensity data is analyzed for

compliance with the minimum lighting rules by the

Indonesian National Standard (SNI). Descriptive analysis

was carried out; the average value of light intensity was

compared to its compliance with SNI rules. The minimum

average light intensity value must be above or equal to 250

Lux. Based on these rules, the results obtained that only

seven of the 25 classes that meet the SNI standard and as

many as 18 classes do not. The data on the results of

measuring natural light intensity can be seen in Table 12.

4.2. Student's Visual Comfort Perception

Data collection is carried out simultaneously with

daylight intensity data collection. After analyzing the

perception data of 737 respondents, the results show that an

averages 3% felt "very comfortable", and 12.5% felt

"comfortable". The highest percentage of respondents who

felt that the level of natural light in the class was

"perceptible" 57.5%. "Perceptible" means that the

respondent is less comfortable, but still perceives that there

is enough light to work well and they are not constrained.

The percentage of students who felt that the level of natural

light was "disturbing" was also quite large, at 20.5%.

"Disturbing" means students already feel uncomfortable

and a little disturbed, but are still able to work. The

percentage of students who felt "intolerable" is 6.5%.

"Intolerable" means students already feel uncomfortable

and find it difficult to work well. Based on a direct

interview between the author and the respondent, when

experiencing this, students overcome it by moving into a

sitting position or turning on an electric lamp when they

feel uncomfortable. The graphs of students' visual comfort

sensations are presented in Figure 2 and Figure 3.


(a)

(b)

Figure 2. (a) Daylight Availability on Desks (DA) Perception Chart; (b)

Overall Daylight Uniformity (DU) Perception Chart

From Figure 2(a), it can be seen that the majority of

students who gave "Perceptible" responses to the

questionnaire regarding Daylight Availability on Desks

felt that the daylight availability is within normal limits and

does not interfere with their activities. From the curve on

the histogram chart, the spread of the data looks normal.

From Figure 2(b), it can be seen that the majority of


questionnaire regarding Overall Daylight Uniformity felt

that the availability of light in the whole class is within

normal limits, is even, and does not interfere with their

activities. From the curve on the histogram chart, the

spread of the data looks normal.

(a)

(b)

Figure 3. (a) Sunlight Comfort (SC) Perception Chart; (b) Glare

Perception (GP) Perception Chart

From Figure 3(a), it can be seen that the majority of


questionnaire regarding Sunlight Comfort felt that sunlight

exposure in the classroom was still within normal limits

and did not cause visual discomfort. From the curve on the

histogram chart, the spread of the data looks normal.

From Figure 3(b), it can be seen that the majority of

students who gave "Disturbed" responses to the

questionnaire regarding Glare Perception felt disturbed by

the glare that occurs in the classroom, but even though they

feel disturbed, they can still tolerate this situation. When

they feel the glare, the students moved into a sitting

position to find a comfortable position. From the curve on

the histogram chart, the data distribution is still in the

normal category.



From all these results, it can be seen that the percentage

of students who feel "Perceptible Comfort" is quite high, at

57.5%. "Perceptible" means that the respondent is not

comfortable, but also does not feel disturbed by the natural

lighting in the classroom. Respondents felt normal, even

though the light intensity was at a number below the

recommended standard. The minimum value of light

intensity in the classroom according to SNI is 250 Lux [42].

According to Idrus, in several schools in Makassar, only

25% met the SNI standards and 75% of the classrooms did

not meet them [44].

4.3. Assessing Daylight Comfort Probability (i-DCP) of

Classrooms

Before determining the variables that were used to

assess the visual comfort of the classroom, Pearson's

bivariate correlation statistics are held first on the

Questionnaire Question. Overall, Daylight Uniformity

(DU), Glare Perception (GP), and Sunlight Comfort (SC)

criteria have a significant correlation with perceptions of

overall visual comfort. Correlation analysis of variables

were performed.

Daylight Availability on Desk (DA) does not seem to

have a strong correlation. As can be seen in Table 5, the

significance value of the three variables DU, SC, GP, are

sig <0.05, and the significance value of DA is sig>0.05. In

addition, asterisks also indicate the level of significance.

Daylight Comfort Probability assessment based on

students' perceptions has been carried out in 25 classes. Six

cases are presented in this paper; two cases representing

ratings that are categorized as "Preferred", two cases

represent the category "Acceptable", and two cases that

represent the category "Not Acceptable/ Preferred".

Daylight Comfort Probability of Classroom assessment

that is categorized as "Preferred" is presented in Table 6

and Table 7 along with the discussion. The Daylight

Comfort Probability assessment that is categorized as

"Acceptable" is presented in Table 8 and Table 9 along

with the discussion. Furthermore, the Daylight Comfort

Probability assessment that is categorized as "Not

Acceptable" is presented in Table 10 and Table 11 along

with the discussion.

Table 4. Results of Statistic Analysis of Student's Visual Comfort (All Cases)

CBDM Intolerable Disturbing Perceptible Comfortable Very Comfortable Sum (%)

sDA DA 1.4 9.6 79.3 8.3 1.3 100.0

DU 3.2 18.3 60.9 15.9 1.8 100.0

ASE SC 5.3 18.2 67.2 9.2 0.1 100.0

GP 15.9 35.9 22.5 16.8 8.9 100.0

Average (%) 6.5 20.5 57.5 12.5 3.0 100.0

Table 5. Results of Statistic Analysis of Student's Visual Comfort (All Cases)

Correlations

Overall Visual

Comfort DA DU GP SC

Overall Visual Comfort

Pearson Correlation 1 .057 .116** .269** .186**

Sig. (2-tailed) .123 .002 .000 .000

N 737 737 737 737 737

Daylight Availability on

Desk (DA)

Pearson Correlation .057 1 .257** .097** -.066

Sig. (2-tailed) .123 .000 .008 .074

N 737 737 737 737 737

Overall Daylight

Uniformity (DU)

Pearson Correlation .116** .257** 1 .096** -.101**

Sig. (2-tailed) .002 .000 .009 .006

N 737 737 737 737 737

Glare perception (GP)

Pearson Correlation .186** -.066 -.101** .109** 1

Sig. (2-tailed) .000 .074 .006 .003

N 737 737 737 737 737

Sunlight comfort (SC)

Pearson Correlation .269** .097** .096** 1 .109**

Sig. (2-tailed) .000 .008 .009 .003

N 737 737 737 737 737

*. Correlation is significant at the 0.05 level (2-tailed)

**. Correlation is significant at the 0.01 level (2-tailed).


Table 6. Statistical Analysis of Student Visual Comfort Data in the Classroom (Case-1)

Classroom

Code

Daylight Intensity (Lux) Orientation

I D P Cf VCf Sum

(%) min max mean 1 2 3 4 5

DU

UP-I 113 371 261 E/W

0 16 80 4 0 100

SC 4 12 80 4 0 100

GP 4 24 0 0 72 100

Average (%) 2.7 17.3 53.3 2.7 24.0 100

Based on the data in Table 6, the assessment Daylight Comfort of Classroom (Case-1) is:

P = 53.3%; Cf = 2.7%; VCf=24%; then (P + Cf+VCf) = 80%

Referring to Eq. (2), the result of Daylight Comfort Probability (i-DCP) in Case-1 is "PREFERRED".


Classroom

Code


I D P Cf VCf Sum

(%) min max mean 1 2 3 4 5

DU

29-I 136 150 143 N/S

0 10 86.7 3.3 0 100

SC 0 10 73.3 13.4 3.3 100

GP 23.3 20 23.3 10 23.4 100

Average (%) 7.8 13.3 61.1 8.9 8.9 100


P = 61.1%; Cf = 8.9%; VCf=8.9%; then (P + Cf+VCf) = 78.9%

Referring to Eq. (2), the result of Daylight Comfort Probability (i-DCP) in Case-2 is "PREFERRED".


Classroom

Code


I D P Cf VCf Sum

(%) min max mean 1 2 3 4 5

DU

29-II 112 145 131 N/S

0.0 37.1 54.3 8.6 0.0 100

SC 8.6 8.6 74.2 8.6 0.0 100

GP 22.9 34.3 17.1 8.6 17.1 100

Average (%) 10.5 26.7 48.5 8.6 5.7 100


P = 48.5%; Cf = 8.6%; VCf=5.7%; then (P + Cf+VCf) = 62.8%

Referring to Eq. (1), the result of Daylight Comfort Probability (i-DCP) in Case-3 is "ACCEPTABLE".


Classroom

Code


I D P Cf VCf Sum

(%) min max mean 1 2 3 4 5

DU

10-I 289 335 318 N/S

3.0 3.0 48.5 36.4 9.1 100

SC 0.0 12.1 60.6 27.3 0.0 100

GP 36.4 42.4 9.1 12.1 0.0 100

Average (%) 13.1 19.2 39.4 25.3 3.0 100

Based on the data in Table 8, the assessment of Daylight Comfort of Classroom (Case-4) is:

P = 39.4%; Cf=25.3%; VCf=3.0%; then (P+Cf+VCf) = 67.7%

Referring to Eq. (1), the result of Daylight Comfort Probability (i-DCP) in Case-4 is "ACCEPTABLE".




Classroom

Code


I D P Cf VCf Sum

(%) min max mean 1 2 3 4 5

DU

UP-III 82 175 119 E/W

0.0 24.1 75.9 0.0 0.0 100

SC 0.0 69.0 20.7 10.3 0.0 100

GP 0.0 96.6 3.4 0.0 0.0 100

Average (%) 0.0 63.2 33.3 3.4 0.0 100


P = 33.3%; Cf = 3.4%; VCf=0%; then (P + Cf+VCf) = 36.8%

The result of Daylight Comfort Probability (i-DCP) in Case-5 does not meet either category.


Classroom

Code


I D P Cf VCf Sum

(%) min max mean 1.0 2.0 3.0 4.0 5.0

DU

29-III 44 58 49 N/S

0.0 48.6 51.4 0.0 0.0 100

SC 25.7 14.3 60.0 0.0 0.0 100

GP 11.4 57.1 8.6 22.9 0.0 100

Average (%) 12.4 40.0 40.0 7.6 0.0 100

Based on the data in Table 8, the assessment of Daylight Comfort of Classroom (Case-6) is:

P = 40%; Cf=7.6%; VCf=0%; then (P+Cf+VCf) = 47.6%

The result of Daylight Comfort Probability (i-DCP) in Case-6 does not meet either category.

Table 12. Assessment of Daylight Comfort in Classroom (All Cases)

CLASS

CODE Orientation

Daylight Intensity (Lux) ( P+Cf+VCf) SNI sDA Perception

Min Max Avg

UP-I E/W 113 371 261 80.0% Comply Preferred

UP-II E/W 113 131 153 89.3% Not Comply Preferred

UP-III E/W 82 175 119 36.8% Not Comply Not Acceptable

ID-I E/W 101 127 108 63.3% Not Comply Acceptable

ID-II E/W 52 70 61 46.9% Not Comply Not Acceptable

ID-IIII E/W 277 367 339 88.0% Comply Preferred

ID-IV E/W 248 269 260 58.3% Comply Acceptable

29-I E/W 136 150 143 78.9% Not Comply Preferred

29-II N/S 112 145 131 62.8% Not Comply Acceptable

29-III N/S 44 58 49 47.6% Not Comply Not Acceptable

29-IV N/S 121 145 138 77.1% Not Comply Preferred

10-I N/S 289 335 318 67.7% Comply Acceptable

10-II N/S 21 26 24 43.8% Not Comply Not Acceptable

10-III E/W 136 147 141 83.3% Not Comply Preferred


04-II E/W 236 274 254 73.6% Comply Preferred

04-III N/S 195 229 209 77.1% Not Comply Preferred

04-IV N/S 185 212 202 90.3% Not Comply Preferred

04-V N/S 449 556 503 68.3% Comply Acceptable

02-I N/S 80 174 148 63.7% Not Comply Acceptable

02-II N/S 19 27 22 46.1% Not Comply Not Acceptable

02-III E/W 25 36 29 47.6% Not Comply Not Acceptable


21-II E/W 224 264 243 82.8% Not Comply Preferred

21-III E/W 250 359 286 74.2% Comply Acceptable


The method is carried out on the 25 classes that are the

object of this research. The results show that there are 12

classes with daylight comfort perceived as "Preferred",

there are 7 classes with daylight comfort perceived as

"Acceptable", and 6 classes with daylight comfort

perceived as "Not Acceptable" and "Not Preferred" (see

Table 12).

5. Discussion

From the stated results, we can see that there are 12 cases

with daylight comfort probability categorized as

"Preferred" and there are 7 classes with daylight comfort

probability categorized as "Acceptable". We can also see

from Table 12 that there are 6 classes that do not fit into

either category. From the measurement of natural light

intensity in the classroom, the results show that as many as

18 classes do not comply with the minimum lighting value

standard by SNI, and only 7 classes comply with the

standard (see Table 12).

From field observations, some classrooms did not

comply with standards because they did not have good

access to natural light. Their daylight access is impeded by

vegetation, such as large trees that are placed very close to

buildings. In addition, another problem is the limited land

owned by the school, which causes the buildings to have to

be too close together, especially if the school is located in

the middle of a densely populated settlement. From the

results, it can be seen that there are 12 classrooms do not

meet the requirements recommended by SNI, but the

results of the Daylight Comfort Probability (i-DCP)

assessment for these 12 rooms are categorized as

"Preferred" and "Acceptable". Students still feel that the

natural light in the class is comfortable and accept the

situation. The SNI method that determines the

recommended light intensity is one of the factors that

affects visual comfort, which is related to the quantity of

light. However, it is not only the quantity of light that

affects visual comfort, but also the distribution of light, and

the presence or absence of glare that occurs in space and

other influencing factors. According to Allan et al. [45],

subjective evaluation is important, in addition to evaluation

of Daylight Performance Metrics (DPMs), because only

doing photometric actions alone does not fully capture the

subjective component of lighting.

6. Conclusions

Research on students' visual comfort assessment in

classrooms and assessments of daylight comfort in

classrooms based on students' perceptions have been

carried out. This research shows that visual comfort is not

influenced by only one factor. An assessment by measuring

the intensity of the room's light has not been able to predict

accurately whether the space is comfortable or not. This

research proposed an alternative approach method for

assessing the visual comfort of classrooms with daylight

based on students' perception. To the best of the author's

knowledge, there has been no previous research using

students’ perceptions to assess the visual comfort of a

classroom. This study shows that, to create visual comfort

in classrooms, the factor of uniformity of light, sunlight

exposure, and glare must be of particular concern, in

addition to the daylight intensity. Visual comfort in the

classroom will be created by considering these factors

together.

Based on SNI, a good classroom has an average light

intensity equal to or above 250 Lux. And, based on this

research, it can be proved that classrooms that meet SNI

standard are categorized as "acceptable" or "preferred" by

the proposed method; however classrooms where light

intensity is below 250 Lux are not necessarily categorized

as "not acceptable" because of other influencing factors.

The daylight uniformity factor is photometrically

influenced by the ratio between the minimum and

maximum illuminance. Glare and sunlight exposure factors

are photometrically influenced by the position of the

building, openings, configuration of the aperture model,

location, and time.

This method is very simple and easy to use for designers

to find out the visual comfort in a room with daylight. Even

so, this method certainly still has limitations and requires

refinement. Repetitive data collection should be done to

obtain more accurate results. In addition to classrooms, it is

also possible to apply this method to other room functions.

In the future, the authors propose assessing the daylight

comfort of a room by using this method for other functions

that also require good visual comforts, such as work spaces,

libraries, laboratories, or drawing studios. This research

opens the opportunity to find a model that can be a

reference for a classroom design in the tropics. The model

must be able to meet the three elements of comfort, namely

uniformity, sunlight comfort, and glare comfort.

Acknowledgments

We would like to thank the Makassar City Government and

the South Sulawesi Provincial Government for their

permission to collect data at the school that was used as the

research sample. We also want to thank all the college

students of the Architecture Department of

Muhammadiyah University Makassar for their

contribution to data collection and surveys.

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A Study on Mechanical and Durability Aspects of Concrete Modified with Steel Fibers (SFs)

Jawad Ahmad1,*, Aneel Manan1, Asif Ali1, M. Waleed Khan2, M. Asim3, Osama Zaid1

1Department of Civil Engineering, Swedish College of Engineering and Technology, Pakistan 2Department of Civil Engineering, CECOS University of IT and Emerging Science, Pakistan

3Department of Civil Engineering, Military College of Engineering, Pakistan


Cite This Paper in the following Citation Styles (a): [1] Jawad Ahmad, Aneel Manan, Asif Ali, M. Waleed Khan, M. Asim, Osama Zaid , "A Study on Mechanical and Durability Aspects of Concrete Modified with Steel Fibers (SFs)," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 814 - 823, 2020. DOI: 10.13189/cea.2020.080508.

(b): Jawad Ahmad, Aneel Manan, Asif Ali, M. Waleed Khan, M. Asim, Osama Zaid (2020). A Study on Mechanical and Durability Aspects of Concrete Modified with Steel Fibers (SFs). Civil Engineering and Architecture, 8(5), 814 - 823. DOI: 10.13189/cea.2020.080508.


Abstract Concrete is weak in tension and strong in compression which results in brittle failure. This is obviously unacceptable for any construction materials. Thus, concrete requires some type of tensile reinforcement to balance its brittle behavior and improves its tensile strength. Adding of fibers is one of the most prevalent techniques to enhance the tensile behavior of concrete. Fiber slows cracking phenomena and increases energy absorption capacity of the structure. Majority researchers focus on mechanical performance of fiber reinforced concrete. In this research, the influence of various dosages of steel fibers (0%, 1.0%, 2.0%, 3.0%, and 4.0% by weight of cement) is investigated on the mechanical and durability properties of concrete. Mechanical properties such as compressive strength and split tensile strength are studied at 7- and 28-days curing. To evaluate the durability aspects of each mix, various parameters such as water absorption, acid attack resistance, and permeability are investigated. Results indicate that strength was increased up to 2% addition of steel fiber and then reduced gradually. It also indicates that, durability parameter of concrete for example water absorption, permeability, and acid attack resistance considerably improved with incorporation of steel fibers at 2.0% incorporation of steel fibers. Therefore, it is recommended to mix steel fibers up 2.0% by weight of cement to achieved maximum benefits.

Keywords Steel Fibers Reinforced Concrete, Compressive Strength, Split Tensile Strength, Water

Absorption, Permeability, Acid Resistant

1. IntroductionIn construction industries, concrete is highest used

material for its high compressive strength. But concrete has very low tensile capacity which results in abrupt failure in concrete structure. Different types of fiber are used in concrete to increase the tensile capacity of concrete under tension loading. Majority Steel fiber reinforced concrete has the capability of brilliant shock resistance, ductility, flexural strength, tensile strength, Crack arrest & fatigue resistance.

In 1910, Porter first recommended the use of steel fibers in concrete [1]. The first research on reinforced fiber concrete in the US was performed in 1963 [2]. A general observation is that thin fibers are more impressive in reducing the width of plastic shrinkage cracks than thick fibers as reported in ACI 544.5R-10 [3]. The positive significance of steel fibers in concrete depends on many factors such as shape, length, type, strength cross section, mix design, matrix strength fiber content, & steel fiber bond strength [4]. Between these high-performing concretes, for the benefits of low cost, easy fabrication, performance improvements, steel fiber-reinforced concrete is used extensively for engineering purpose [5, 6].


However, the study showed that uneven incorporation of steel fiber would affect the fluidity and uniformity of concrete mixing and even result in fiber bonding, which eventually affects the reinforcement effect of mechanical properties” [7–9].”

“Steel fibers efficiently increase the load carrying capability of slab & also allows the structure to behave more flexible. steel fibers more than 0.38% marginally enhance the ultimate load and also improve the slab flexibility [10]. Research displayed that unequal adding of SFs will affect the concrete uniformity and fluidity in mixing & even bonding of fiber, which ultimately influence mechanical performances [11]. steel fibers significantly improve in early as well as long term compressive strength of concrete [12–16] . Steel fibers behave as crack stoppers and not as cracks prevention. Steel fibers are known to enhance tensile capacity of post-cracking behavior [17].Steel fibers have displayed more significant effects on flexural tensile strength [18]. Experiments results indicate that increase in fiber quantity will result to improve ductility, toughness, & strength [16, 19] . Modulus of elasticity of fiber concrete raises with increase in the fiber quantity [20]. Adding of SFs in concrete not only raise the strength but also the ductility [13].They realized that fiber increased the peak pull-out load [21].SFs can enhance the tensile strength of concrete to almost 40% [22]. Moreover, the use of fibers helps in reducing the bleeding and permeability of concrete [23–26].”

“A brief overview of existing literature shows that a very scarce number of studies investigated durability of steel fibers reinforced concrete . [27] Investigated the mechanical performance of fiber reinforced concrete in Pakistan. They have reported the positive influence of SFs on mechanical performance. Further research was recommended [27], to study the durability of SFs reinforced concrete. Therefore, the present study evaluates durability aspects of steel fibers reinforced concrete. Steel fibers were added in proportion 0%, 1%, 2%, 3% and 4% by weight of cement. Test results suggest that performance of concrete considerably improved with incorporation of steel fibers.

2. Experimental Program

2.1. Materials

2.1.1. Cement Ordinary Portland cement (OPC) type-1 in accordance

with American Standard of Testing Materials ASTM C150 [28] was used in the making of concrete mixes. Its chemical and physical properties are displayed in Table 2.

Table 1. Physical and Chemical Property of OPC

Chemical Property

Percentage (%)

Physical Property Results

Ca0 63.7 Size ≤ 75µ

SiO2 24.9 Fineness 91%

Al2O3 6.4 Normal Consistency 29%

Fe2O3 3.7 Initial Stetting Time 33min

MgO 4.5 Final Stetting Time 411min

SO3 0.9 Specific surface 322 m2/kg

K2O 1.4 Soundness 0.60%

Na2O 1.2 28-days

compressive Strength

42Mpa

2.1.2. Steel fibers (SFs) Straight steel fibers were obtained by cutting binding

wire into 35 mm long length. Its properties are given in table 2.

Table 2. Physical Property of Steel Fibers Physical Property Results

Length 35mm

Diameter 0.55mm

Aspect ratio (L/d) 64

Tensile Strength 1345Mpa Young’s Modulus 200GPa

2.1.3. Aggregate Natural sand was used as a FA (fine aggregate) in all

the mixes in SSD (saturated surface dry) condition which was obtained from local market Risalpur Pakistan. Physical properties of fine were given in the Table 3.Normal weight coarse aggregate (crush stone) with nominal maximum size 25mm was used as aggregate in all the mixes in SSD (saturated surface dry) condition which was obtained from local market Risalpur Pakistan. Different tests were conducted to evaluates its physical properties. Its Physical properties were given in Table 3.

Table 3. Physical Property of Fine and Coarse Aggregate

Physical Property Fine aggregate Coarse Aggregate

Particle Size 4.75mm to 0.075mm 25mm to 4.75

Fineness Modulus 2.73 5.7

Absorption Capacity 4.28% 2.18%

Moisture Content 2.8% 0.45% Bulk density

(kg/m3) 1626 1560

816 A Study on Mechanical and Durability Aspects of Concrete modified with Steel Fibers (SFs)

2.2. Constant Parameter

Quantity and cement type, quantity and type of aggregates, Water cement ratio and Mix design will be kept constant throughout the study.

2.3. Variable Parameter

The dose of steel fiber is the variable element in all Mixes, starting from 0% to 4% by weight of cement.

2.4. Super Plasticizer

Chemrite-530 was used as super plasticizer because it is high range water reducing admixture and non-toxic and non-hazardous under relevant health and safety issue. Chemrite-530 is a very capable super plasticizer with a set retarding effect for production of free-flowing concrete in hot climate. The super plasticizer meets the requirements of EN 934-2 T 3.1/3 [29]. and ASTM C-494 Type F [30]. Typical properties of the super plasticizer are given as under Table 4.

Table 4. Physical Property of Superplasticizer

Property Result

Color Brown

Relative density 1.48 at 25°C

Chloride content < 0.1%

Physical state Liquid

2.5. Tests and Size of Specimen

ASTM C39/C39M [31]Cylinder of standard size (6x12in) will be used to measure the compressive strength at 7 days & 28 days. Similar cylinders of standard size (12 x18in) will be cast & tested to find their tensile strength as per ASTM standard [32].Three specimens are tested for each test at 7&28 days and the mean value of the specimens is considered as strength. For durability assessment, as per ASTM C642 [33], 50mm thick and 100mmdiameter discs are casted for water absorption test. A circular truncated cone of size Φ175 × 150 × Φ185mm are used to find permeability resistance as per E30-2005 JTJ [34]. For acid resistant, A 100mm cubical specimen of varying NFs mix was cured in 4% acid (H2SO4) solution for 7 14 and 28 days. Acid solution was changing every week to maintain 4% concertation. The acid attacks were measured in terms of mass loss (%) due to sulfuric acid (H2SO4) attacks.

2.6. Sample Preparation Method

ASTM C-31[35] method was followed for the preparation of the specimens and compaction was done manually by Roding in three layers having 25 blows per layer. A total of 60 samples having a standard size will be cast & then will be tested. To study the effect of SF (steel fiber) on the behavior of hardened and fresh concrete, five mixes are prepared. Details of the mixes are provided in the following table 5.

Table 5. Quantification of Materials

Mix SFs (Kg)

Super plasticizer (kg)

Compressive Strength

Split Tensile Strength

Water Absorption

Test

Acid Attack Resistance

Test

Permeability Resistance

Test

SF-0% 0.0 4.25 3+3 3+3 3+3+3 3+3+3 3

SF-1% 4.25 4.25 3+3 3+3 3+3+3 3+3+3 3

SF-2% 8.5 4.25 3+3 3+3 3+3+3 3+3+3 3

SF-3% 12.75 4.25 3+3 3+3 3+3+3 3+3+3 3

SF-4% 17 4.25 3+3 3+3 3+3+3 3+3+3 3

No of Samples 30 30 90 90 15

Total No of sample = 255



3.1. Harden Property

3.1.1. Compressive Strength Compressive strength is the measure of greatest

compressive loading that concrete can withstand. The compressive strength test is performed under the standard procedure of ASTM as ASTM C39/C39M [31] for cylindrical samples having standard dimensions as 150mm diameter and 300mm length as shown in Figure 1 at the ages of 7 and 28 days.

Based on experimental test outcomes compressive strength increased as the percentage of steel fiber raised up to 2% and then decreased as displayed in Figure 2. After 28

days of curing, highest compressive strength was obtained at 2% dosage of steel fiber which was 25% higher than from reference concrete. However, beyond 2% dosage the strength was reduced.

The positive effect on compressive strength is due to the confinement of the fiber reinforcement on the specimen. Compression produces an expansion laterally and with it, a tension and shear. The tension and shear are resisted by the fibers. Therefore, compression is increased. When % of fibers is high this confinement can reduce transversal deformation of specimen and increase its compressive strength. When increasing the steel fiber percent specially of higher dosage the process of compaction will be difficult and then the compressive strength will be reduced. The finding is in the line as per previous studies [12–16].

Figure 1. Casting and Setup for Compressive Strength

Figure 2. Compressive Strength Results


3.1.2. Split Tensile Strength

Tensile strength for concrete samples is called the tensile stresses generated due to applying compressive load at which the concrete sample may fail. According to ASTM C496-71[32], split cylinder test was carried out on cylindrical specimens of 150 mm diameter and 300 mm height as shown in Figure 3 at the ages of 7 and 28 days.

Figure 3. Setup for Split Tensile Strength

Figure 4. Split Tensile Strength Results


Based on experimental test results split tensile strength increased as the percentage of steel fiber raised up to 2% and then decreased as displayed in Figure 4. As per previous study [17], Steel fibers (SFs) behave as crack stoppers and not as cracks prevention. Steel fibers are known to enhance tensile capacity of post-cracking behavior. After 28 days of curing, highest split tensile strength was obtained at 2% dosage of steel fiber which was 43% higher than from reference concrete. However, beyond 2% dosage the strength was reduced. Steel fibers are mixed in concrete to increase the flexibility of concrete by halting the onset of tension cracks or preventing the generation of cracks in such manner that tensile strength of (SFRC) steel fiber reinforced concrete displays better conduct than normal concrete. It can be also concluded that SFs more positively tensile strength than compressive strength [18]. The following equation can be used to predict split tensile strength from compressive strength of concrete.

𝑓sp = 0.53 x �𝑓c (1)

Where fc (MPa) is compressive strength and fsp (MPa) is split tensile strength of cylindrical sample.

Comparison of predicted values with experimental tensile strength values using ACI-318.11 codes is displayed in Figure 5. Equations (1) can be used to predict values of split tensile strength which uses compressive strength. It is noticed that all empirical values locate well

within the anticipated values using ACI-318.11 codes. Regression models between split tensile strength & experimental values of compressive strength are displayed in Figure 5. A strong correlation exists (R2 > 0.90) between both strength parameters.

3.2. Durability

3.2.1. Water absorption Water absorption is indirect measurement of concrete

durability. Mostly harmful chemicals are present in water. These chemicals react with concrete constituents, which changes the properties of concrete. Extra water present in the pore of concrete as results freeze and thaw effect because of change in temperature, which results crack of concrete. Therefore, water absorption test was conducted on 7, 14 and 28 days with varying proportion of SFs. Water absorption test results were displayed in Figure 5. A general trend indicates that water absorption capacity of fibers concrete decreased as the percentage of SFs increased. Elastic modules of normal concrete are lower than fibers reinforced concrete. So, addition of SFs would lead to increased tensile properties of concrete and as a result it would restrict the formation and development of initials cracks [36]. In other words, density of concrete is increased which would lead to water absorption of concrete decreased.

Figure 5. Co Relation Between Compressive Strength and Predicted Split Tensile Strength


Figure 5. Water Absorption

3.2.2. Acid resistance

Although there are various aggressive acids, such as hydrochloric acids, nitric acids, sulfuric acids (H2SO4) and acetic acids. In this study, H2SO4 was taken as a acid strike, on concrete sample with various ratios of SFs. The test results of acid resistance are shown in terms of mass loss due to sulfuric acid attack of the specimens after 7, 14 and 28 days for each blend as shown in Figure 6. It can be noted that weight loss due to sulfuric acid considerably decreases with addition of fibers. It is due to fact that addition of SFs effectively restricts the development and formation of initial cracks and decreases porosity of the concrete [36], which avert fast penetration of sulfuric acid. Erosion of concrete is basically dissolution of calcium aluminate and calcium hydroxide due to sulfuric acid [37–39]. Erosion speed will largely depend on sulfuric acid penetration rate into the concrete body and to reach calcium hydroxide and calcium aluminate. So, improvement in the porosity of concrete results increased in density of concrete due to addition of steel fibers. The raise in density would lead to less penetration rate of sulfuric acid in concrete.

Figure 6. Acid Resistance


Figure 7. Permeability Permeation Depth

3.2.3. Permeability

Circular truncated cone specimens were used for the permeability resistance test. The dimensions of the cone were Φ175 × 150 × Φ185 mm [34]. As well know that concrete is a porous material [40, 41]. To characterize concrete durability, Permeability is considered as a fundamental material property as it determines the penetration rate of aggressive materials which are responsible for degradation of concrete [40].

Outcomes of permeability test were shown in Figure 7. A general trend demonstrate that permeation depth decreed as the percentage of steel fibers increased. Minimum permeation was obtained at control mix while maximum permeation depth was obtained at 4% of steel fiber (by weight of cement) 6 mm which is about 72% lower than control mix. It is due to fact that elastic modulus of steel fibers reinforced is much greater than that of normal concrete. Therefore, the tensile capacity of concrete increased as the percentage of steel fibers increased. This would effectively restrict initial cracks development and formation, and the porosity of the concrete could be reduced, which would be beneficial to improving the permeability resistance of concrete [36].

4. Conclusions Based on experiment tests, following conclusion has

been drawn. Strength was raised up to 2% dosage of steel fiber and

beyond 2% steel fiber strength was gradually decreased. However, beyond 2% dosage the strength was reduced but higher than from the reference concrete for all mix. It was due to the confinement of

the fiber reinforcement on the specimen. When % of fibers is high this confinement can reduce transversal deformation of specimen and increase its compressive strength. However, at higher dosage compaction comes to be more difficult which results porous concrete and hence strength was reduced.

Durability such as water absorption, acid resistant and permeability considerably improved with SFs. It is due to fact that Steel fibers (SFs) behave as crack stoppers. This would effectively restrict initial cracks development and formation, and the porosity of the concrete could be reduced. Therefore, durability aspects (water absorption, acid resistant, permeability) improved.

From this study we can recognize that addition of SFs has enormously raised the strength as well as durability of concrete.

Conflicts of Interest The authors have no conflict of interest to declare.

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DOI: 10.13189/cea.2020.080509

Evaluation of Ventilation System Efficiency with

Reference to Ceiling Height in Warm-Humid

Climate of Pakistan

Sadia Farooq1, Faiza Zubair2, Mohammad Arif Kamal3,*

1Department of Science, University of Home Economics, Pakistan 2Department of Family and Consumer Sciences, University of Home Economics, Pakistan

3Architecture Section, Aligarh Muslim University, India



(a): [1] Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal , "Evaluation of Ventilation System Efficiency with

Reference to the Ceiling Height in Warm-Humid Climate of Pakistan," Civil Engineering and Architecture, Vol. 8, No. 5,

pp. 824 - 831, 2020. DOI: 10.13189/cea.2020.080509.

(b): Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal (2020). Evaluation of Ventilation System Efficiency with

Reference to the Ceiling Height in Warm-Humid Climate of Pakistan. Civil Engineering and Architecture, 8(5), 824 - 831.

DOI: 10.13189/cea.2020.080509.


Abstract This research is about the effectiveness of

ventilation systems for human thermal comfort concerning

the height of the ceilings which contribute to green

building structures, especially for residential areas. One of

the greatest challenges in architecture is the cost of

mechanical ventilation and the need for energy demand for

cooling in hot and humid climates. The study is based on

quantitative data of the selected houses, keeping constant

the areas, location, elevation features, plant placement, and

open spaces. Temperature records for 20 days of 10 low

ceiling houses (LCH) and 10 high ceiling houses (HCH)

with ventilators, 200 observations each, are compared

using independent sample t-test. The mean temperature is

15.31°C in LCH and 13.88°C in HCH, with the difference

of 1.43°C so the alternative hypothesis that there is a

significant difference between the average temperature of

LCH and HCH with ventilators, is accepted. The other

benefits of ventilation cannot be ignored which we get in

the high ceiling houses. This would also help to reduce

moisture, smoke, odor, heat, dust, and bacteria.

Keywords Ventilation System, Ceiling Heights,

Warm-Humid Climate, Pakistan

1. Introduction

The Globalization has a drawback to increase the energy

demand with an impact on the environment such as

pollution, ozone depletion, temperature increases, and

above its scarcity of resources [1]. In the past few decades,

houses are constructed with a low ceiling height which

does not contribute much to the exchange of air from inside

and outside. With all other professional challenges,

architecture has to face to develop a living space with

thermal comfort and to lessen the mechanical ventilation to

control heat [2]. About 40% of the global energy

consumption is spent in the built environment [3]. There

has been a lot of reliance on energy-consuming technology

in cooling and ventilation system to achieve thermal

comfort in buildings [4]. The spaces must be constructed to

provide comfort to the users [5]. The inside space works on

the phenomena of convection when air moves upward

when it gets hot and cool air travels down [6] so in the hot

humid climate, the natural way of lowering the temperature

is high ceilings with ventilators. The studies also have

shown that the variation in temperature or thermal level can

be up to 4°C because of the height of the ceiling or good

ventilation or both of them [6]. Ventilation is also effective

in maintaining the air quality and comfort; the poor indoor

air quality is the fourth largest environmental threat to the

world [7].

Ventilation is needed for the discharge of air from inside


to outside and to get fresh outside air to decrease indoor

poisons, dampness, and smells. Contaminants, for example,

formaldehyde, unstable natural mixes, and radon can

gather in inadequately ventilated homes. Abundance

dampness in a home can create high moistness. Static air

can promote harmful ingredients such as toxic gases in

homes. When too minimal open-air enters a home, toxins

can once in a while aggregate to levels that can present

wellbeing and solace issues. Moreover, one way to deal

with bringing down the convergences of indoor air toxins

in the house is to expand the measure of open-air coming in.

There are various mechanical ventilation gadgets, from

exhaust fans that discontinuously expel air from a solitary

room, for example, restrooms and the kitchen, to air

dealing with frameworks that utilizes fans and ventilation

system to consistently evacuate indoor air and

appropriately separate and adapt to open air to vital focuses

all through the house. In any case, the cost that we pay for

ventilation gadgets, it drives us to keep away from the

establishment of ventilators, even where required [8],[9].

The financially savvy framework and vitality sparing is

the common ventilation. The common ventilation is the

ventilation of a structure with outside air without the

utilization of a fan or other mechanical framework. It tends

to be accomplished with operable windows when the

ventilation requirement is for a small space. The warm air

in the structure can raise and exhaust out subsequently

driving fresh air from outside to inside the building

structure normally through openings in the lower regions

[8].

If we look at the efficiency of high ceilings, we can

conclude that the system of natural ventilation works well

in high ceiling houses, because of the space available for

air to rise and move outside which also leaves the area for

fresh air. The high ceiling houses are friendlier with a

natural ventilation system than low ceiling houses. Cross

ventilation can be easily done in high ceiling houses

because as warm air rises it gets excess to the outdoor open

area through ventilators. This seems difficult in low ceiling

houses [7,10]. Even people are constructing low ceiling

houses due to cost issues. Several studies have been

conducted in several climates about environmental thermal

behaviour. This study has indicated the influence of ceiling

height and the presence of ventilators as a key factor in

thermal comfort about good ventilation. The house planned

according to the ventilation requirements naturally, would

reduce energy consumption as well as expenditures during

the building’s lifetime. It is also worth mentioning to add

height as a rule in countries’ building codes [7],[11].

2. Significance and Objective of the Study

The research helps the public to decide whether they

want to construct and design their houses for natural

ventilation, or to design for mechanical ventilation. Natural

ventilation through high ceilings may cost high at the time

of construction but helps in reducing the cost of ventilation

in the building phase of a house. Effective ventilation in the

houses is the present-day need, to reduce the use of

mechanical ventilation as well as to reduce the energy and

cost paid for ventilation. The study is conducted, to

compare the temperature verification in both high and low

ceiling houses. The other aspect of the study is that the

ventilation system not only reduces the temperature but

also keeps the house humidity and moisture level to the

standard points. The positive points of ventilators are first

to reduce the temperature of the house, keep the house cool,

energy-efficient, cost-effective, discharge of stagnant air,

the entrance of fresh cool air, and maintained levels of

humidity, moisture, and dew point.

The main objectives of the study are:

To analyse the effectiveness of ventilation systems in

high ceiling houses.

To compare the temperature differences in low and

high ceiling houses.


One of the ways to have more cool air in the spaces is

through the provision of high ceilings and proper

ventilation in warm and humid climate, the present study

also focused on this scenario but the alternate of it is a low

ceiling in cold climates. Several types of research have

been discussed here, in both ways as low ceiling and high

ceiling, in conclusion basically to get the solution

according to climates. Many types of research focused on

thermal comfort concerning cold climates where it is meant

to be a collection of warm air inside the buildings.

Hashimoto and Yoneda (2009) presented the variations

in ceiling heights and their impacts with thermal load and

ventilation through analyzing spaces with CFD software–

Computational Fluid Dynamics – and presented the results.

The situation showed that the higher level of air layers is

hot and can provide thermal comfort in cold climate [12].

The indoor environmental air quality can be maintained to

provide comfortable heat and cold levels which can also

result in human comfort and building energy use reduction

[13]. Further, the results of Lam and Chan, Zuo and Zhao

and Schiavon, Hoyt, et.al. Jradi, Sangogboye, Mattera,

Kjærgaard, Veje, Jorgensen in their respective researchers

analyzed that thermal environments presented temperature

verifications in buildings [14],[15],[13],[11].

Guimares et al. studied the impact of ceiling height and

thermal comfort of buildings in Brazil as a hot weather

location. The ceiling height has been varied of 2.4m, 2.8m,

and 3m. Results showed that temperature increases 1 ºC per

each 20 cm. The high and low airwaves can vary up to 4 °C.

The Upper and lower layers of the indoor environment can

reach up to 4°C [6]. Ghafari, Mirrahimi, Heidari also

address the issue of the neglected area in the field of

826 Evaluation of Ventilation System Efficiency with Reference to Ceiling Height in Warm-Humid Climate of Pakistan

influence of ceiling height on heating energy consumption

in the cold climate still has not been dealt with in-depth.

This paper sheds new light on reducing the heating energy

consumption by conducting the variation of ceiling height

[16].

3.1. The Need for Natural Ventilation

Aside from vitality issues, ventilation is significant,

because it influences private air quality, which thusly

influences wellbeing, solace, and building usefulness.

Verifiably, a blend of penetration from flawed envelopes

and inhabitant-controlled openings (for example windows)

ventilated our homes. Until the vitality emergency of the

1970s, numerous individuals thought this ventilation was

adequate without administrative intercession, and there

was less worry about the private indoor condition. Today,

the Environmental Protection Agency records that to

maintain the quality of air inside the rooms is the fourth

biggest ecological risk to our reality. This expanded

familiarity with the indoor condition is because of a few

subjective changes in our homes. One change is that new

houses are more vitality productive because of improved

development strategies, for example, diminished air

spillage, expanded protection levels [7].

3.2. The Purpose of Natural Ventilation

The buildings need ventilation for the exchange of air

from inside to outside to diminish indoor poisons, the

suddenness, and aromas. Toxins and impurities, for

instance, formaldehyde, eccentric normal blends, and

radon can accompany the homes without ventilation. The

American Society of Heating, Refrigerating and

Air-Conditioning Engineers suggest having proper

ventilation in homes at a pace of 0.35 air changes each hour

or 15 cubic feet for every individual each minute. If too

minimal open-air enters a home, contaminations can some

of the time amass to levels that can present wellbeing and

solace issues [7]. Similarly, one way to deal with bringing

down the convergences of indoor air poisons in your house

is to expand the measure of outside air coming in.

The air crossing is possible because of penetration and

ventilation whether natural or mechanical. When the air

flows into the house at a fast speed it travels and cool or

warm down the temperature inside the rooms. When the

speed of air is slow inside the rooms, the air contamination

may remove slowly [7],[17]. Most of the houses have

mechanical devices and exhaust fans for the removal of

contaminated or warm air, including fumes outside the

home [18]. In a perfect world, new homes will be worked

to limit spillage to control vitality misfortune, improve

comfort, and limit the vehicle of dampness and

contaminations through the structure shell. These homes

should then additionally have mechanical ventilation to

expel contaminations produced in the home and give open

air in a controlled way. Regardless of whether a mechanical

ventilation framework bodes well in your current homes

relies upon the house, your current warming, ventilation,

and cooling (HVAC) framework, and the progressions you

have arranged [7],[13].

3.3. Cost for a Fully Naturally Ventilated Building

Structures that utilize natural ventilation may cost high

because the openings and windows increase in construction

cost as windows cost 5% to 10% more than a wall covering,

yet the reserve funds from not utilizing cooling will

counterbalance this additional expense. Half and half

frameworks of open ducts will be increasingly costly in

light of the greater expense for operable windows and

interlocking controls for the HVAC framework. Expenses

shift incredibly relying upon the establishment of heating,

ventilation, and air conditioning (HVAC) framework, the

cost is decided on the intricacy of the framework and the

functions programmed or controlled [7].

3.4. Indoor Air Quality and Pollution

With the deficiency in home ventilation, toxins can

develop and turn out to be extremely thought. These

poisons originate from numerous sources, are

progressively hazardous when joined with high moistness

levels, which is another issue related to the lack of

ventilation in homes. At the point when humidity is

excessively high, the decay of inside interior can become

major issues. Another issue with high dampness is dust

bugs. Each home has dust vermin and they flourish in moist

surroundings. That is the condition to worry for individuals

who experience the ill effects of residue vermin

sensitivities [14,20,19,21].

The carbon components can raise the toxins inside the

home without proper ventilation. Proper ventilation in

homes can help lessen sensitivity and asthma side effects

and can aid in the curing of respiratory issues that weight a

huge number of individuals [20]. Low moistness, then

again, can be a reason of throat and nose bothering and dry

skin. The danger from pets, pollen allergies, lead, mole

spores, dust mites, tobacco smoke, chemicals, paints, and

pesticides can be a portion of the regular toxins that can

develop without satisfactory home ventilation [22].

3.5. Natural Cross-ventilation

The cross ventilation relies upon two ceaselessly

evolving components: wind accessibility and wind course.

Thusly, it is a to some degree questionable hotspot for

giving wind stream and warm solace. In cross ventilation,

the breeze makes a high-pressure area to affect the

structure and a low-pressure area on the lower side (Figure

1). Weight is most noteworthy close to the focal point of

the windward divider lessening to the corners as the air


finds different approaches for movement around the

structure so air admissions are best close to the inside or the

high-pressure zones [22],[23]. The open area for

ventilation is approximately 25% and smaller for small

spaces. The airflow must reach in congested areas [24].

Natural ventilation is the ventilation of a structure

without the utilization of a fan or other mechanical

framework. It tends to be accomplished with operable

windows when the space is small. In progressively

complex frameworks, warm air in the structure can be

raised and went out from the upper vents to the outside in

this way driving fresh, low-temperature air to come inside

the structure normally through the vents in the lower

regions. These frameworks utilize next to no vitality,

however care must be taken to guarantee the inhabitants'

solace. In a hot and humid climate like in our region, the

warm air raises automatically regularly. Air-side

economizers play out a similar capacity as characteristic

ventilation, however, utilize mechanical frameworks' fans,

pipes, dampers, and control frameworks to present and

convey cool open-air when fitting [23].

Wind striking a building generates a region of higher

pressure in the direction of its incidence (windward wall)

while the sides, i.e., leeward wall and roof are subjected to

a reduced pressure. A pressure gradient created in the

direction of the incident wind causes the air to flow through

openings in the buildings. Windows play a dominant role

in inducing ventilation. Ventilation rate is affected by

climate, wind direction, size of inlet and outlet openings,

volume of the room, shading devices and the internal

partitions [25]. Evans studied the effect of air flow related

to the position of inlet and outlets in the wall. The actual

wind flow in the building is due to the combined effect of

thermal and wind forces [26].

Figure 1. Pressure Effect of wind on the building

3.6. Low Ceiling Houses

Low ceiling houses range from nine feet to ten feet in

height, even less than this. In the present situation, people

preferred a low ceiling house to reduce the cost of

construction. These houses require mechanical devices

used for ventilation which increases the energy

consumption and cost expenditures of the building while in

use because of low ceiling houses without ventilators have

minimum outlets for exchange of air. It also increased the

need for cooling the house in summer by split conditioners

and fans. These things use electricity which we cannot

make by ourselves so we pay for it. Low ceiling houses

reduce the cost at the time of construction but raise the cost

we pay later on for mechanical ventilation. Because air

cannot pass freely from these houses so they remain humid

and warm. The house size restricted people to the indoor

environment of the house and they live with artificial

means of cooling and ventilating the house. Even these

artificial methods are used for comfort but they are also

having side effects on the human body such as ultra-violate

rays coming out of air conditioners and freezers then heat

gain in nature which is also damaging the ozone layer [27].

3.7. High Ceiling Houses

In the past decades, most of the houses were constructed

with a high ceiling almost eleven to thirteen feet high. The

benefits which they provide to the residents are that high

ceiling raises the efficiency of the ventilation process. They

are more-airy, cool, and lower in temperature. They

provide an automatic or natural system to ventilation which

also controls humidity, moisture, and dew point with in the

rooms, a natural ventilation system works on the principle

of osmosis that if the air has more contamination, it will go

towards the air which has low contamination and will

exchange to balance the air contents . A common person

might be unaware of the benefits of those houses and wish

to build high ceilings just because of trends of those times.

But now it is open that the high ceilings also contributed to

ventilation and cooling. Now the need is to create

awareness in people about its benefits and if go into the

depth, those houses not only contribute to ventilation but

too many other factors adjoined with ventilation. There is

not any best method than to ventilate the house by natural

ways and high ceilings are very convenient to build and to

get their benefits [17],[21],[22],[24],[27],[28].

4. Research Methodology

The research is based on quantitative survey approach to

compare the efficiency of ventilation systems in the high

ceiling and low ceiling houses.

4.1. Sample

The sample consists of High Ceiling Houses and Low

Ceiling Houses in warm-humid climate of Pakistan. Two

different localities are selected in the city of Lahore

because these localities were having both types of houses,

HCH and LCH, required for the study. The two localities


are Samanabad and Iqbal Town of Lahore. The total

sample size was twenty houses.

4.1.1. Sample Description

They range from ten marlas (2723sqft.) to one kanal

houses (5445sqft).

Their specific features are mentioned with each of them

about elevation features such as surrounded by trees,

buildings, open areas, etc.

Most of them are fully constructed on the ground floors

with two to three rooms on the first floor.

4.1.2. Low Ceiling Houses

They are having low ceilings that are almost 9’ to 10’

(feet). Some of the houses were having a false ceiling and

all houses were not having ventilators at the upper level of

walls, in the rooms which were included in the study. Even

the windows were present but most of the house habitants

were using air conditioning devices (Fig 2).

Figure 2. Low Ceiling with Cooling Device and Small Window

4.1.3. High Ceiling Houses

They are having high ceilings than low ceiling houses

that are almost 11’ to 13’ (feet) with ventilation. The

ventilation is provided through ventilators or large

windows (Fig 3). Ventilators were present in most of the

rooms at the upper level on the walls in the rooms, which

were included in the study.

Figure 3. High Ceiling with windows

4.1.4. Instrumentation

The Mercury Thermometer is used to measure climatic

ambient air temperature.

4.2. Data Collection

The residents of selected sample houses are involved in

the study. They are provided with the instruments to

measure the inside temperature of the house. They noted

down the temperature daily. The temperature was recorded

three times during the day. The researcher was provided a

file to be filled by the residents daily. Time to note the

temperature was tried to be fixed in the morning, afternoon,

and evening. The study was limited to the city of Lahore

and the duration for the study is twenty days starting from

27th December to the 15th of January and only twenty

houses were selected (ten high ceiling and ten low ceiling

houses).

5. Data Analysis and Interpretation

The data was collected from the residents after the end of

the duration and analysed by statistical terms. The data

taken from the weather department was also used to

analyse and compare the differences in temperatures. The

averages were counted of the data taken from the house to

evaluate the effectiveness of the ventilation process and

temperature differences. The mean temperature of low and

high ceiling houses and the difference in mean temperature

in residents’ recorded temperature and temperature by the

Weather Meteorological department (WMD) is given in

Table 1.

5.1. Low Ceiling Houses

Mean Temperature of Ten Houses = 154.35°C /10 =

15.43°C

Mean. Temp. of Twenty Days by Weather Metallurgical

Department (WMD) = 9.9°C.

The difference in the Temperature taken from Houses

and from the WMD = 15.43 - 9.9 = 5.53°C.

5.2. High Ceiling Houses

The Mean Temperature of Ten Houses = 138.01°C

/10=13.80°C.

The Mean Temperature of Twenty Days by Weather

Metallurgical Department (WMD) = 9.9°C.

The difference in the Temperature taken from Houses

and from the WMD=13.80 - 9.9 = 3.9°C

The temperature differences of 5.53°C and 3.9°C,

respectively in LCH and HCH show that the overall

temperature of houses recorded by WMD varied which

shows that the LCH have high temperature [29], [30]. The

difference of 1.43°C in temperatures of LCH and HCH also

concluded that HCH has low temperatures because of

ventilators.


Table 1. Difference in mean temperature recorded by Residents and WMD.

Mean Temp.

Temp. recorded

by Residents

(0C)

Temp. recorded

by WMD

(0C)

Difference

in Temp.

Mean (0C)

Low Ceiling

Houses 15.43 9.9 5.53

High Ceiling

Houses 13.87 9.9 3.9

5.3. Comparison of Average Temperature in Houses

Average temperatures of the low ceiling and high ceiling

houses have been compared graphically by using multiple

bar charts. Figure 4 shows the comparison of average

temperature in LCH and HCH. It can be seen that the

average temperatures in LCH are higher than the HCH.

Figure 4. Comparison of Average Temperature in Low and High

Ceiling Houses.

5.4. Testing of Hypothesis

Data on temperature for LCH and HCH were analyzed

by applying independent sample T-test to check the

significance of the difference between the temperatures of

two kinds of houses.

The Null and Alternative hypotheses are stated as under:

H0: There is no significant difference between the

average temperature of low ceiling houses and high ceiling

houses with ventilators.

H0: There is a significant difference between the average

temperature of low ceiling houses and high ceiling houses

with ventilators.

Level of Significance: 5%.

5.5. Test Results

The data were analyzed using Statistical Package for

Social Sciences (SPSS) and the results are stated in table 2.

Table 2. Data and Average Temperature of Low and High Ceiling Houses

. Group N Mean Std.

Deviation

Std.

Error

Mean

t.var I 200 15.31 2.86 .20225

t.var II 200 13.88 2.78 .19659

Table 2 shows the summary of the statistical analyses

performed on the data.

Group 1 represents LCH and Group II represents high

ceiling houses. It can be seen that the average temperature

of HCH is less which is 13.88 °C than LCH which is

15.31°C. Average so it is visible that high ceiling designs

with ventilators are effective in lowering the temperature.

Table 3. T-Test Results and Mean Difference of Temperature.

. T df Sig.

(2-tailed)

Mean

Difference

Std. Error

Difference

t.var 5.114 398 .000 1.442 .28205

Table 3 shows the value of t-Statistic=5.114 along with

the degrees of freedom=398 and the P-value (sig. 2-tailed)

= 0.000, and the mean difference of temperature=1.44 °C.

5.6. Analysis of the T-Test

As the P-value of the test=0.00 <0.05 (assumed level of

significance) which indicates that the null hypothesis is

rejected. It can be concluded that there is a significant

difference in the mean temperature of HCH and LCH. It is

also evident that the mean temperature of HCH is less than

that of LCH.

6. Discussion and Conclusions

Environmental degradation is because of the resource

unlimited and unrealistic use but careful consideration of

materials and methods to use resources can reduce the

negative impacts on humans [1],[2],[3]. One of the

methods is ventilation, even we are spreading a lot on

mechanical ventilation but natural ventilation is also

effective [7]. People consider a low ceiling for the cost

issues but researches favored a high ceiling for natural

ventilation and air quality [8],[9]. The researcher tried to

select the sample which would be having the same features

such as lawn, back yard, trees, plants, etc. the temperature

of selected sample houses was recorded thrice daily. It was

concluded that the ventilation process is affected by the

height of the ceiling and the use of ventilators, higher the

ceiling height the lower is the temperature. The analysis of

the data showed the difference in temperature is highly

significant and high ceiling houses have lower average

temperatures than LCH. This temperature difference would

affect the inner environment to keep it cool and that is

because of the efficiency of ventilation in high ceiling

houses so the height of the ceiling can contribute to the

ventilation system. The ventilation process works more

effectively in high ceiling houses than LCH. The

temperature difference in LCH and HCH is 1.44 °C so the

hypothesis i.e. the ventilation system is more effective in

cooling the houses constructed with high ceilings than

houses with low ceilings is accepted [25],[28]. Some of the

design issues are also mentioned here which were


concluded from the literature such as cross ventilation is

very effective in homes, the windows must cover 25% area

of the room size, the ventilators work more successfully at

a height in rooms and the ventilators need to cover 1/20 of

the floor area [17],[23].

The findings of the study show the effectiveness of the

ventilation system in high ceiling houses. Now a day’s

people mostly started construction with low ceilings, to

minimize the cost of construction. People use to construct a

false ceiling to lower the height of the ceiling that

maximizes the cost of construction. This helps in keeping

the house cool in summers but it is not effective in air

movement and ventilation. The facts are telling that even a

low ceiling is cost-effective at the time of construction but

in the long run, a high ceiling helps to reduce the cost paid

for ventilation and cooling of the house. The study can also,

be replicated between the high ceiling houses with and

without ventilators.

Acknowledgements

The researchers are grateful to the owners of the houses

who helped in the study for the data collection and

temperatures of their houses.

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Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia

Mithen Lullulangi1,*, Armiwaty Tawani1, Rahmansah2

1Department of Architecture, Faculty of Engineering, Universitas Negeri Makassar, Indonesia 2Department of Civil Engineering Education, Faculty of Engineering, Universitas Negeri Makassar, Indonesia


Cite This Paper in the following Citation Styles (a): [1] Mithen Lullulangi, Armiwaty Tawani, Rahmansah , "Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 832 - 837, 2020. DOI: 10.13189/cea.2020.080510.

(b): Mithen Lullulangi, Armiwaty Tawani, Rahmansah (2020). Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia. Civil Engineering and Architecture, 8(5), 832 - 837. DOI: 10.13189/cea.2020.080510.


Abstract Mamasa is one of the ethnic groups in West Sulawesi, which has a very unique culture, and the implementation of that culture is seen in the form of traditional architecture in the form of a house as a place to live, as well as other activities such as a traditional grave. This study determines the typology of traditional grave architecture in Mamasa, West Sulawesi, one of the traditional architectural products with high cultural value. This is a qualitative research with data collected through interviews, field observations, and documentation. The qualitative data analysis comprises of collection, presentation, reduction, and drawing conclusions. The results showed that the typology of traditional grave architecture in Mamasa emerged from the ancestral belief in Aluk Mappurondo, which consisted of 5 types, including a) Bangka-Bangka, b) Tedong-tedong, c) Ropi, d) Batutu oralang-alang, and e) Lokko'. The contribution of this research is to introduce one of the traditional architectural products that has high cultural value, as an object of research for scientists interested in traditional architecture or in the field of anthropology, and at the same time contribute in the field of tourism, as a cultural attraction that attracts both local tourists and foreign tourists, for the sake of increasing the country's foreign exchange in the field of Tourism.

Keywords Typology, Architecture, Grave, Traditional, Mamasa

1. IntroductionThis study was conducted in collaboration with the

Makassar State University and the Regional Planning and Development Agency (BAPPEDA) of Mamasa Regency to produce an inventory of the traditional architecture in Mamasa. The inventory includes houses, granaries, and graves, which are all archaeological objects of ancient relics with high cultural values, as well as the materials required for the planning and development of this area as a leading tourism destination in the West Sulawesi province.

Ambo, stated that studying the complex architecture of ancient graves does not only involve addressing tombstones; rather it also offers general knowledge concerning certain circumstances such as how the customs supported the concept of the cemetery, the engraved messages for pilgrims, choice of materials used, and so on [1].

The architectural development of graves in Mamasa is inseparable from civilization and culture, particularly matters relating to religion. Before the Dutch migrated to this area, the culture was entirely influenced by people's belief in Aluk Mappurondo (ancestral religion). According to Als Makatonan, Aluk Mappurondo involves four laws of life, namely: 1) Pa'totiboyongan or matters governing agriculture, 2) Pa'banne tauan or matters governing marriage, 3) Pa 'bisuan or decrees that regulate human life from birth until death, and 4) Pa'tomatean or matters relating to the death ceremony. Therefore, burial procedures and the architecture of the grave are also characterized by people’s beliefs [2]. The death ceremony


in the Mamasa area is referred to as Rambu solo (smoke coming down). Kaubi stated that this ritual disturbs the eyes, because it is associated with the tears of the grieving person, which flows in a downward direction similar to the flow of a river. This represents the journey of the departed soul to the spirit world (Pollondong) [3].

Therefore, ancient civilization enriched with rules rooted in the beliefs of the ancestors gave birth to various types of traditional grave typologies in the form of artifacts. Presently, they are still found in several places in Mamasa.

Ching reported that typology is interpreted as a systematic classification of a group of objects based on similar characteristics. However, there is also the tendency to classify elements based on compactness randomly, and visual features possessed [4]. Furthermore, Barliana stated that it is the study of types derived from the word Typos (Greek), which means impressions, images, or figures. Types are often used to describe the general shape, structure, or character of a particular form or object [5].

In numerous places and ethnic groups in Indonesia, the issue of grave typology related to tombstones is widely discussed as archaeological products. In ancient times, there was no tombstone because the dead were buried with large wooden coffins perforated on both sides. The various types of wooden coffins are also inseparable from the knowledge of mythology and the development of civilization, which has been passed down from generation to generation. Kaubi and Buijs, stated that according to mythological stories, the sky touches the earth at the northern hemisphere, while the sea serves as a mediator between the sky and the underworld [6]. This led to the historical background of the traditional ship-shaped houses in Mamasa, particularly the decorative art referred to as Badong, which is placed both in front and at the back. Buijs, reported that the exhibition of Badong reinforces the fact it is an ancient tradition compared to Tongkonan in Toraja [7]. It also related to the belief that their ancestors arrived by ship through a large sea that connects the sky and earth, which is strengthened by research on Chant for the Deceased conducted by Van der Veen [8].

Buijs, stated that the end of life is marked by the journey to Pollondong using ships (Bangka-Bangka) with various decorations similar to badong. [7] Van der Veen, reported that in Toraja, ship-shaped coffins, referred to as erong were used in the past. However, these coffins are still being used in Mamasa, and they are referred to as bangka-bangka [8]. Furthermore, Buijs, stated that the exhibition of small badong in coffins during the burial ceremony refers to the ancient belief that after death, people return to the spirit world through the sea. A sculpture that resembles a guardian or driver of the dead through the journey is placed on top of the badong [7]. This is based on the belief that when people die, they return to their initial place of origin and are regarded as a god. Buijs, defined burial as the preparation for the journey to heaven to become an ancestral god (membali dewata). Generally, the Mamasa people believe that when an individual dies, it is not

considered to be dead. However, the person is assumed to be lao membali dewata or has transitioned a god that blesses and offers health to the family members in the world [9].

Whenever an individual dies, a series of ceremonies are in accordance with customary rules such as slaughtering chickens, pigs, or buffalo. This act is carried out to mark the person’s final departure, and into the spirit world known as Indo 'Robo (Volkman) [10]. According to Mandadung, the slaughtered animals serves as a vehicle for the dead and shows the social status and wealth obtained, while on earth [11]. Furthermore, Buijs stated that the purpose of these sacrifices is not merely to provide guests food but also serve as dishes for the Lord of the Spirit World or lead to transcendent places in the afterlife [9].

The explanation of the experts offers an explicit description of the ancestral belief (Aluk Mappurondo) in Mamasa, concerning the journey of the dead to the spirit world (Pullondong), using ships (Bangka-Bangka). However, some people argued that the dead ride on the spirits of animals slaughtered during the Rambu Solo ceremony held. Both of these opinions have a strong basis, and presently, archaeological evidence is determined in the architectural typologies of the graves in Mamasa.

2. Material and Methods The purpose of this study is to determine the

architectural typology of traditional graves. This is a qualitative research, with data collected through interviews, field observations, and documentation. The data analysis technique is a qualitative review of data collection, presentation, reduction, and conclusions (Miles) [12].

3. Research Result Several traditional villages in Mamasa Regency and

community burial sites were visited, particularly the ancient graveyards, and various types of graves were examined as follows:

1. Bangka-Banga

In Mamasa or Limbong Kalua, the oldest type of grave consists of a corpse placed in perforated and covered wood either in the form of bangka-bangka (modeled as a boat) or tedong-tedong (shaped like a buffalo). According to the results from the interviews conducted on parents in the traditional villages visited, among others, Demmamala (75-year-old) from Buntuballa reported that the oldest grave models are Bangka-Bangka. Demmamala further stated that this type of grave had been in existence for long. Its age was estimated to be hundreds of years ago. This remark is supported by Demmaloga (85 years old) from Malabo reported that the grave model is old and no longer used. A similar opinion was expressed by the late PH.

834 Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia

Pualillin from Tawalian, and several other parents. None of the respondents interviewed, knew the exact age of this type of grave. Besides, both foreign and national works of literature were consulted, and none of them offered any valid data concerning the age of this grave. Even the literature written by Anggipurnamasari, and published by the Ministry of Education and Culture reports that the graves of Bangka-Bangka and Tedong-Tedong are hundreds of years old. The search results showed that this grave model was only found in Karassik Minanga Buntuballa, West Balla Village, in Paladan village, Sesena Padang sub-district, and Osango village, Mamasa sub-district and the condition was threatened with extinction. Fortunately, the one in Karassik Minanga of West Balla village has been turned into a tourist attraction and treated appropriately by the Department of Tourism [13].

This type of grave is made of large round or perforated logs in which the corpses are placed. The model is similar to a boat, and the cover is constructed of large wood as depicts the roof of a boat, the end of the grave is ornamented with buffalo head, while some are only decorated with small badong. These coffins are made of uru, a class I type of local wood that is durable and tends to last hundreds of years, assuming it is protected from the rains. This grave type is shown in Figure 1.

Source: Research Results

Figure 1. Types of Bangka-Bangka graves in Karassik Minanga Buntuballa

It is placed in Tadan, a kind of cottage specifically made for graves to protect it from being destroyed by the soil, which usually has a strong wooden base. In this modern era, the cement floor is made to ensure archaeological objects do not become extinct.

According to studies, several corpses were buried in one coffin, and when an old corpse decays and shrinks, a new

one is added. Therefore, a Bangka-Bangka contains dozens of corpses, as shown in Figure 2.


Figure 2. Weathered Bangka-bangka with many skulls indicates that one grave contains many corpses

2. Tedong-Tedong

The second oldest type of grave is Tedong-tedong. It is fabricated from strong uru logs, and the model has changed. It no longer resembles a boat; rather, it is shaped like a buffalo. The initial forms of these graves are similar to the Bangka-Bangka; however, due to civilization and an increased number of local geniuses, a leg was constructed to protect the grave from coming in direct contact with the ground to prevent weathering. Furthermore, it was inspired by the belief that the buffalo sacrificed at the funeral was the vehicle of the dead to Pollondong; therefore, local geniuses developed and fabricated horns and tail ornaments. The tomb is completed with its head resembling a buffalo, and it was referred to as Tedong-Tedong. There is no valid data to support the age of this graveyard. Anggipurnamasari, stated that the tomb in Minanga is a funeral center for the Kondo Sapata area, which comprises Lambanan in Mamasa sub-district, Tabang in Pana Sub-district and Rante Bulanan in Mambi Sub-district and it takes 2 (two) or 3 (three) days to arrive in Karassik Minanga Buntuballa at Balla District [13]. Furthermore, it was stated that the displacement of regions due to flooding that had hit the area was approximately 300 years ago, according to the Historical and Archaeological Data Collection Report of Mamasa Sub-district in 1986. Therefore, this age described only the current position, without stating when this type of grave became existent. Likewise, Mandadung, only reported that the tomb of Tedong-tedong in Karassik Minanga Buntuballa is hundreds of years old [14]. This type of grave is shown in Figure 3.



Figure 3. Tedong-tedong grave seen from the front shows the legs and head ornaments and horns like a buffalo that is standing.


Figure 4. Tedong-tedong grave seen from behind shows the legs and tail ornaments clearly

3. Ropi

This type of grave is only found in Saloan village, Pana District. The material is made of uru logs that are perforated at the front in the direction of the fiber or annual wood dings and not at the top such as Bangka-Bangka and Tedong-Tedong. Therefore, it is perforated like a tunnel, with one end closed, and the other used as a door to place the corpse. None of the respondents were able to provide certain information about its existence. This type of grave is not as popular as the Bangka-Bangka and Tedong-Tedong, because only few studies have been conducted in this remote village. This type of grave is shown in Figure 5.


Figure 5. Grave of Ropi type made of round wood, which is perforated like a tunnel without ornamentation, and made a door to insert a corpse.

4. Batutu Batutu is also another type of traditional graveyard made

of uru wood. It is a small house with a door to place the corpses. Irrespective of the fact that it is considered a traditional grave, it is more modern than the previous types. It is found in almost every village in Mamasa, particularly the Eastern and Central regions except Mamuju in the West. Anggipurnamasari (2015) stated that Liang Batutu is made of wood and constructed in the form of a Mamasa traditional house. Some are black in color with corpses are wrapped in clothes and placed in the grave after the burial ceremonies. This tradition is common in Rante Buda, Lambanan, Pala, and Kariango. Examples of these graves are shown in Figure 6.


Figure 6. Grave Type of Batutu

836 Architectural Typology of Mamasa Traditional Graves, West Sulawesi, Indonesia

The Batutu structure is constructed from strong uru wood, with roof materials made of fern trunks. The proportions and ornaments resemble the decorations placed in front and at the back of the traditional Mamasa house, although they are smaller in size. This development is based on the increasing number of dead people and the fact that previous grave types no longer meet the demands of burial. Therefore, the people decided to construct a bigger grave to accommodate more bodies. This type of grave is usually owned by wealthy aristocratic families and is still used to date.

In some regions in Mamasa, such as Tabone, Messawa, Nosu, and Pana's areas (the southern part of Mamasa Regency), it is referred to as alang-alang. This type of grave has been modified and modern structural materials, namely cement, bricks, and roof covering from zinc or other industrial products, are presently used in its construction. An example is shown in the following figure.


Figure 7. Graves of Batutu (alang-alang) type in Messawa and Tabone with roofs using modern structural materials, such as zinc roofs and metal roof tiles

5. Lokko’ This type of grave is a large artificial cave in the rocks

which is used as a public cemetery, by a particular village. The entrance is usually as wide as the door of an ordinary house. However, there is a large room inside the cave, the center is used as the hallway, while the left and right hand side consist of porches in which the bodies are placed. Tadan, which is similar to a small house, is built in front of the door to protect it from the rains.

After this discovery, the Dutch introduced Christianity, and traders popularized Islamic teachings. Therefore, the burial procedures and architecture of the graves were heavily influenced by both religions. After that era, the dead Christians or Muslims are buried by digging a grave in the ground. However, most of them, particularly the Christians, believed that the form of burial does not

contradict religion. Therefore, some of the people still use batutu, Alang-Alang or Lokko.


Figure 8. Tadan Lokko’ in Orobua

4. Discussion The teachings of aluk mappurondo showed that the

ancestors of Mamasa arrived from a distant land, in ships or boats. This is a fundamental aspect of the story sengo-sengo padang written by Als Makatonan, which stated that the Mamasa ancestors (Pongkapadang) originated from Toraja Sa'dan, and met with the supposed Torije'ne from China, when their boat was stranded in Buntubulo, they got married, reproduced and died to become the ancestors of the Mamasa people [2]. According to the teachings of Aluk Mappurondo, when someone dies, the person is referred to as Loa Membali Dewata (Going to be a God). Buijs, stated that a person's burial prepares them for heaven to become ancestral gods (membali dewata), which according to mythological stories, is illustrated as Pollondong, a place of the spirit in the sky which is related to the sea in the northern hemisphere as reported by Kaubi and Buijs. The means of transportation are either a boat or a ship. Therefore, when people die, they are buried in a grave constructed in the form of a boat usually referred to as Bangka-Bangka a representative of the ship used by the spirits of the dead to travel to Pollondong. Therefore, the first traditional graves in this area are Bangka-Bangka. This is supported by ancestral beliefs and the opinions of experts that have conducted research in this area [9] [3] [6].


The initial architecture of the Bangka-Bangka graves enabled it to be placed on the surface of the ground in a protective hut called Tadan. However, it is eaten by termites and is eventually destroyed. This led to the need to construct poles or legs initiated by local geniuses, which was also supported by the belief that slaughtered animals are used as a means to Pollondong (Mandadung) [11]. Therefore, the shape of this bangka-bangka evolved into tedong-tedong equipped with ornamental variations, such as horns and tails. According to this research, it is the second type of grave in this area and is supported by several field facts, such as the discovery of several bangka-bangka whose ornamentation resemble the head of a buffalo, besides the small Badong (Buijs) [9].

Another grave type referred to as Ropi is found in Saloan. However, according to this study, it is a type of bangka-bangka grave, which does not possess an artistic touch; only the logs are perforated.

Furthermore, bangka-bangka and tedong-tedong have limited capacity. Due to an increase in death rate, the Batutu or alang-alang was developed. This type of grave also has limited capacity therefore mass graves such as an artificial cave in rocky hills referred to as Lokko' are constructed in each village. Presently, the traditional type of grave popularly used by the public is Batutu or alang-alang which has been modernized as private graves, besides Lokko'. Furthermore, the Muslim and some Christian communities have practiced the usual method of burying corpses in the ground.

5. Conclusions Based on the results and discussion from this study, it

can be concluded that the typology of the architecture of traditional graves in Mamasa, which relies on ancestral beliefs as stated by Aluk Mappurondo, consists of 5 types, namely: 1) Bangka-Bangka, 2) Tedong-tedong, 3) Ropi, 4) Batutu or alang-alang, and 5) Lokko.

Acknowledgments The authors are grateful to the Government of Mamasa

Regency through the Chairman of the Regional Planning and Development Agency (BAPPEDA) that collaborated and financed this research. The authors are also grateful to the Chairperson of the Department of Civil Engineering and Planning, Makassar State University, for facilitating this research and the entire Mamasa community.

REFERENCES [1] Ambo, Asse Ajis. Pengetahuan Umum Tentang Ciri Khas

Kompleks Makam Kuno di Aceh. 2019. https://www.ajnn.net/news/pengetahuan-umum-tentang-ciri-khas-kompleks-makam-kuno-di-aceh/index.html

[2] Als, Makatonan. Ada’ Mappurondo. Hal. 2-4, dan 19. Kendari : Gepsutra. 1984.

[3] Kaubi, Jeanine. Rambu Solo’, La fumee descend; La culte des morts chez les Toraja du sud. Page.347 and 402. Paris: Centre de Documentation et de Recherches sur Iasie du Sud-est et le Monde Insulindien. 1982.

[4] Ching, FDK. Architecture Form, Space and Order. New York: Van Nostrand Reinhold Company. 1979.

[5] Barliana, Syaom M. Tradisionalitas dan Modernitas Tipologi Arsitektur Masjid. Jurnal Dimensi Teknik Arsitektur Vol.32 No.2 Hal. 110 – 118. 2004.

[6] Buijs, Kees. Powers of blessing from the wilderness and from heaven; Structure and transformations in the religion of the Toraja in the Mamasa area of South Sulawesi. Page.60. Leiden : KITLV Press. 2006.

[7] Buijs, Kess. Tradisi Purba Rumah Toraja Mamasa Sulawesi Barat Banua sebagai Pusat Kuasa Berkat. Hal.100. Makassar: Penerbit Ininnawa. 2018.

[8] Veen, H. Van der.. The Sa’dan Toradja chant for the decceased. Page. 32. The Hague: [KITLV. Verhandelingen 45]. 1966.

[9] Buijs, Kees. Kuasa Berkat dari Belantara dan Langit Struktur dan Transformasi Agama Orang Toraja di Mamasa Sulawesi Barat. Hal. 92-93. Makassar: Penerbit Ininnawa. 2009.

[10] Volkman, Toby Alice. Feast of honor; Ritual and change in the Toraja highlands. Page. 103. Urbana: University of Illinois Press. 1985.

[11] Mandadung, Arianus. Budaya daerah Mamasa. Hal. 11. Ujung Pandang: n.n. 1999.

[12] Miles, Matthew B. Et al. Qualitative Data Analysis. Sage Publishing. 2014.

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[14] Mandadung, Arianus. Sejarah Pariwisata Mamasa dan Pola Perjalanan Wisata Kabupaten Mamasa. Hal.70. Mamasa : Lembaga Pelayanan Informasi Kepariwisataan 2017.


DOI: 10.13189/cea.2020.080511

Experimental Investigation on Augmenting the

Discharge over Ogee Spillways with Nanocement

N. Muthukumaran1, G. Prince Arulraj2,*

1Department of Civil Engineering, Karunya Institute of Technology and Sciences, India 2Karunya Institute of Technology and Sciences, India

Received August 3, 2020; Revised September 4, 2020; Accepted September 29, 2020


(a): [1] N. Muthukumaran, G. Prince Arulraj , "Experimental Investigation on Augmenting the Discharge over Ogee

Spillways with Nanocement," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 838 - 845, 2020. DOI:

10.13189/cea.2020.080511.

(b): N. Muthukumaran, G. Prince Arulraj (2020). Experimental Investigation on Augmenting the Discharge over Ogee

Spillways with Nanocement. Civil Engineering and Architecture, 8(5), 838 - 845. DOI: 10.13189/cea.2020.080511.


Abstract Due to urbanization, the infiltration has

decreased drastically resulting in more runoff. Due to this,

dams are receiving more runoff than the design runoff. To

avoid over topping of dams due to this excess runoff, the

capacity of the spillways has to be augmented. The

objective of this research is to determine the effect of nano

material on increasing the discharge capacity of Ogee

spillways. Ogee spillways were constructed in a

rectangular flume. Experiments were carried on a tilting

flume of size 10 m X 0.55 m X 0.6 m. The Ogee spillway

model was fabricated and plastered with cement mortar 1:3.

Three slopes were used and laboratory experiments were

performed with varying heads. Another Ogee spillway was

made and plastered with cement mortar 1:3 in which 30 %

cement was replaced with nano cement. The discharges for

the three slopes (0.003333, 0.007778, and 0.012222) were

found for Ogee spillway plastered with cement mortar and

also for the Ogee spillway plastered with 30 % of nano

cement by varying the heads between 0.5 cm and 5 cm

above the crest of the spillway in steps of 0.5 cm. It is found

that spillway with 30 % nano cement replacement gives

more discharge than the spillway plastered with normal

cement mortar. Experimental investigations related to

porosity, roughness height and SEM analysis also prove

that replacement of nanomaterial improves the surface

smoothness and hence increasing the carrying capacity of

the spillway.

Keywords Ogee Spillway, Ordinary Portland Cement,

Nanocement, Porosity, Roughness Height, SEM Analysis

1. Introduction

Spillway is one of the most important structural

components of a dam. Spillways also function as

‘diverting agents’ for excess amounts of water that is

diverted to different canals, thereby the safety of the dams

are ensured. The three major components of spillway are

(i) Control structure which admits flow to the spillway (ii)

Discharge channel which conveys the flow from the

control structure to the stream bed below the dam (iii)

Terminal structures are energy-dissipating devices that are

provided to return the flow to the river without serious

scour or erosion at the toe of the dam.

The Ogee spillway is also known as S-shape control

weir. Ogee spillway represents the shape of the

downstream face of the weir. It is an improved form of a

straight drop spillway. The profile of the spillway is made

in accordance with the shape of the lower nappe of the

free-falling jet. The shape of the lower nappe of the

free-falling jet can be determined by the principle of

projectile. The jet falls clearly over the face of the

spillway and the gap between the jet and the face is kept

ventilated. In ogee spillway, the falling water is made to

glide over the curved profile of the spillway.

Ogee spillways play a major role in energy dissipation

effectively and discharge of flood safely over its

downstream end. When water falls from higher head to

lower head, it produces high amount of kinetic energy at

the foot of the spillway and hence it is necessary to

dissipate energy effectively, otherwise it will create

scouring, erosion on its chute surface [1]. The Ogee shape


was first investigated by Bazin H.E. [2], and many authors

studied the physical model data from USACE and USBR.

[3-5]. In 1950’s the US Army corps of Engineers focused

on the water discharged over spillways [6]. The Ogee

spillway functioning similar to a dam, provides the safe

passage of water thereby prevent flooding. In engineering

terms, they can be compared in function to safety valves

in boilers. Generally, Ogee spillways are utilized as flood

release structures on dams [7]. Updating the criteria

required for safe hydraulic structures to keep pace with

the changes in climate and potentiality hazardous after

effects on structural integrity and capacity resulted in the

need for continuous expansion and up gradation of

spillway capacities to increase the discharge [8].


2.1. Factors Affecting Spillway Design

2.1.1. Safety Considerations Consistent with Economy

Improperly designed spillway or spillways of

inadequate capacity will lead to failure in dams. Properly

designed structure of adequate capacity may be found to

be only moderately higher in cost than a structure of

inadequate capacity.

2.1.2. Hydrological & Site Conditions Figures Caption

The spillway design and its capacity depend on inflow

discharge, its frequency, shape of the hydrograph, Dam

height, Geological and other site conditions.

2.1.3. Topographical Features

The important topographical features which affect

spillway design are steepness of terrain, amount of

excavation and possibility of its use as embankment

material, the possibility of scour, slope stability, safe

bearing capacity of soils and permeability of soils [9].

2.2. Literature Review

Arun Joji, et.al designed a spillway for a composite dam

proposed at Kanthalloor as a part of Pattiserry irrigation

project. Pattiserry irrigation project envisages construction

of 140 m long and 23 m high composite dam, earthen bund

with concrete overflow section, across the river chengalar a

tributary of Pambar River, located in Kanthalloor village.

The project was aimed to irrigate 240 Ha of land in

Marayoor area, through 8 km long unlined canal. Ogee

type spillway was suggested for the proposed dam [9].

Dhaktode Asaram, et.al carried out an experimental

investigation to determine the effects of different slopes of

ogee spillway surface on energy dissipation. Three ogee

spillway models were prepared with slope of 1:1, 0.85:1,

and 0.75:1. Experiments were carried out to investigate the

energy dissipation. It was observed that the values of

relative energy loss varied between 67% and 87.17%,

65.03% and 85 %, and 67.20 % and 85.20%, for spillway

models with slopes 1:1, 0.85:1, and 0.75:1, respectively

[11].

Mamok suprapto carried out the experiments in the

flume setup, Hydro laboratory, Faculty of Engineering of

Sebelas Maret University. He used Labyrinth Sharp Crest

Spillways (LSCS) to increase the capacity without

lowering spillway crest. Six kinds of LSCS have been used

in the research. Ogee prototype was made of wood and

LSCS was made of acrylic. During the experiment, water

was allowed into the flume with varying discharge. At

different heads above the spillway, the discharge was

measured. Observation has been done both on the Ogee and

LSCS. He concluded that the ability of LSCS to discharge

water was greater than Ogee spillway. Water flowed

through the LSCS, particularly trapezoid type-1, was about

170% more than that of the Ogee spillways [10].

Harinarayan Tiwari.et.al investigated on the methods to

improve the hydraulic competence of spillways. From the

study they concluded that, Piano Key Weir (PKW)

technology can play a role under the simple fact that it does

not inhibit stream flow due to absence of any gate control

system. They also concluded that PKW creates water

storage in stream itself without involving rehabilitation

[16].

Amir kbbas kamanbedast et.al used a physical model to

study the surface roughness on ogee spillway. Hydraulic

performance graph and the appropriate discharge

coefficients were determined. To determine these

parameters, they carried out an investigation on a physical

hydraulic model. Supreme complex Khuzestan Water and

Power Industry performed measurement test. They

observed the hydraulic parameters and analyzed discharge

coefficient in different field including surface roughness in

ogee spillway model. Totally 6 types of surface roughness

and 5 different flow rates were considered. As a result, they

concluded that relative roughness of spillway increases

with decreases in surface roughness and cavitation index

[17].

Alpaslan Yarar developed an analytical and Artificial

Neural Network (ANN) model to estimate the discharge

value passing over Ogee Spillways and the results were

compared. A flume having 7.5 cm width, 15 cm depth and

5 m length, was used in the laboratory. Discharge values

above the spillway were measured for different heads.

Discharge values were also computed by the formula for

the measured heads. In this study, it was aimed to

investigate the performance of ANN on determining the

discharge over the ogee spillways. For this purpose, both

experimental and analytical studies were done. It was seen

that ANN model produced very accurate results. Overall,

the studies presented in this paper showed us that ANN

model can be an alternative method to determine the

discharge value passing over the spillways [18].

Although the literature may appear exhaustive, no report

840 Experimental Investigation on Augmenting the Discharge over Ogee Spillways with Nanocement

is available on usage of nanomaterial to increase the

carrying capacity of existing spillways. In this study nano

cement was used along with cement and sand for plastering

the exterior surface of the spillway with the objective of

increasing the discharge.

2.3. Properties of Materials

The normal size of the cement particles ranges between

50 μm and 90 μm. The sizes of nano cement particles

range from few nanometers to a maximum of about 100

nanometers. These nano cement particles properties

improve the compressive strength of the concrete, lower

environmental contamination, provide a thinner final

product and have faster setting time and are cost effective.

The nanoparticles in the mortar make a smooth surface

with less pores and good durability. Nano cement was

produced by grinding the Ordinary Portland Cement (OPC)

of grade 53. OPC was converted into nano cement by

grinding OPC in a Ball mill grinder [12]. The nano

cement had size between 90 nm to 200 nm. In this study

M-Sand was used as a fine material for plastering the

spillway.

2.4. Experimental Flume Setup

A tilting flume of size 10 m x 0.55 m x 0.60 m was

used for carrying out the experiments. The flume consists

of an inlet chamber, flume portion and a collecting tank.

Water is allowed inside the inlet chamber using three

centrifugal pumps of power 5 hp, 3 hp and 2 hp. Water

from the inlet chamber was allowed through two vertical

layers of weld mesh in order to reduce the turbulence. The

flow in the flume can be controlled by two gates, one at

the entrance and the other one at the end of the flume. In

order to measure the discharge, a collecting tank of size

4.2 m x 0.7 m x 0.6 m is kept at the end of the flume. A

piezometer fixed in the collecting tank was used to find

the time required for 15 cm rise in the collecting tank. The

bed slope can be adjusted. In order to visualize the flow, a

transparent perspex sheet is fitted in the middle portion of

the flume. A hook gauge fitted on a trolley was used to

determine the depth of the flow. The fabricated tilting

flume is shown in (Figure 1).

Figure 1. Tilting flume

2.5. Parameters for the Study

In this experimental study there are two parameters i)

depth over spillway ii) bed slope. The depth considered in

this study was varied from 0.5cm to 5cm. Two spillway

models were constructed in the rectangular tilting flume.

The first spillway model was plastered with CM 1:3. The

second one was plastered with CM by replacing 30% of

nano cement.

2.6. Design of Ogee Spillway

Ogee spillway is widely used in concrete, masonry and

earthen dams. In the earlier periods the Ogee spillways

were designed based on Bazin’s Profile. To overcome the

negative pressure which causes the danger of cavitation

and other factors such as hydraulic efficiency, stability

and economy, various modified profiles have been

proposed.

Several standard ogee shapes have been developed by

U.S army corps of engineers at their Waterways

Experimental Station (WES). Such shapes are known as

‘WES standard spillway shapes’. The d/s profile can be

represented by the equation [13].

𝑥𝑛 = 𝐾𝐻𝑑𝑛−1𝑌

Where,

(X, Y) are the coordinates of the points on the Ogee

profile with the origin at the highest point of the crest,

called the apex. Hd is the design head including the

velocity head. K and n are constants depending upon the

slope of the upstream face.

In this study, the slope of the upstream side face of the

spillway is made vertical, the value of K is taken as 2 and

the value of n is considered and the above equation

becomes

x1.85 = 19.98.y

Coordinates were calculated using the above equation

and the profile of the spillway is shown in (Figure 2).

Figure 2. Downstream profile of the proposed spillway model tilting

flume


2.6.1. Fabrication of Ogee spillway

The following steps have been followed to fabricate the

Ogee spillway. Ogee spillway was constructed inside the

tilting flume using bricks in cement mortar 1:3 and cured

for seven days.

Two spillways were constructed for conducting the

experimental study. Cement Mortar (CM) 1:3 was used to

plaster the first spillway. In the second spillway, CM in

which the 30% nano cement was replaced with cement was

used to plaster the surface of the spillway. Fabricated Ogee

spillway is shown in (Figure 3).

Figure 3. Ogee spillway

2.6.2. Experimental procedure

Series of tests were conducted to determine the effect of

nano cement in increasing the discharge capacity of the

spillway. Three slopes 0.003333, 0.007778 and 0.012222

were used for the study. The slopes used belong to the

category of mild slope. Since most of the natural channels

and rivers have only mild slope, only mild slope was used

for the present study. The head over the spillway and the

discharge are given in Table 1.

(Figure 4) shows the stage discharge graph for spillways

with and without nano cement when the channels slope was

0.003333. (Figure 5) shows the stage discharge graph for

spillways with and without nano cement when the channel

slope was 0.007778. (Figure 6) shows the stage discharge

graph for spillways with and without nano cement when

the channels slope was 0.012222.

Figure 4. Stage discharge graph for a slope of 0.003333




Table 1. Discharges over the spillway for various heads

Sl.No Depth

(cm)

Discharge (m3/s)

CM 1:3 CM with30 % nanocement

Slope 1

(0.003333)

Slope 2

(0.007778)

Slope 3

(0.012222)

Slope 1

(0.003333)

Slope 2

(0.007778)

Slope 3

(0.012222)

1 0.5 0.000367 0.000452 0.000390 0.000548 0.000630 0.000731

2 1 0.001019 0.001023 0.001081 0.001565 0.001620 0.001639

3 1.5 0.001826 0.001968 0.002084 0.003140 0.003758 0.003919

4 2 0.003658 0.003821 0.003953 0.004585 0.004878 0.004930

5 2.5 0.005331 0.005878 0.006113 0.006113 0.006743 0.007164

6 3 0.006044 0.007688 0.007905 0.008336 0.008651 0.009651

7 3.5 0.009189 0.010189 0.009755 0.010421 0.010917 0.012421

8 4 0.011463 0.012736 0.012392 0.013485 0.013800 0.014328

9 4.5 0.013485 0.015811 0.015284 0.016375 0.016982 0.017635

10 5 0.016982 0.017635 0.017982 0.020841 0.021935 0.022841

Table 2. Percentage increase in discharge of spillway with nanocement

Sl.No Depth(cm)

% increase in 30 % of Nano cement

Slope 2

(0.007778)

Slope 2

(0.007778)

Slope 2

(0.007778)

1 0.5 49.22 39.29 87.56

2 1 53.58 58.30 51.53

3 1.5 71.99 90.98 88.03

4 2 25.36 27.66 24.73

5 2.5 14.67 14.71 17.19

6 3 37.93 12.53 22.08

7 3.5 13.40 7.14 27.32

8 4 17.65 8.35 15.63

9 4.5 21.43 7.41 15.38

10 5 22.73 24.38 27.02

The percentage increase in the discharge values for the

spillways with nano material are given in Table 2.

From (Figure 4), (Figure 5), (Figure 6) and Table 2, it

was observed that the discharge over the spillway

increases for the spillways with nano cement. The

percentage increase varies between 13.40 and 71.99 for

the spillway with 30% nano cement for the slope

0.003333. The percentage increase varies between 7.14

and 90.98 for the spillway with 30% nano cement for the

slope 0.007778. The percentage increase of discharge

varies with 15.38 to 88.03 for spillway with 30% nano

cement for the slope 0.012222.

The discharges over the spillway with normal cement

mortar and spillway with 30% nano cement were

compared. It is observed that the discharge over spillway

with 30% nano cement is more. The reasons for the

increase in the discharge are smoother surface and

reduced porosity of the surface when nano cement was

used.

2.7. Analysis of the Results

2.7.1. SEM Analysis

The Nano cement particles were prepared by ball

grinding the cement particles. Properties of nano cement

include the high compressive strength, increase in

smoothness and reduction in the roughness of the surface.

The reduction in the roughness increases the flow rate.

These Nanoparticles also fill the pores of the mortar and

hence a smoother surface is obtained.

The SEM images of normal cement mortar (CM 1:3)

and cement mortar with 30 % of nanocement are given in

(Figure 7) and (Figure 8) respectively.


Figure 7. SEM images of normal cement mortar (CM 1:3)

Figure 8. SEM images of cement mortar with 30 % of nanocement

From the SEM images, it can be seen that the nano

sized particles present in the mortar make the surface

smooth and hence the discharge increases.

2.7.2. Surface roughness

Surface roughness often called as roughness, is a

component of surface texture. It is quantified by the

deviations in the normal vector of a real surface from its

ideal form [14, 15]. If these deviations are large, the

surface becomes rough; if they are small, the surface is

smooth. Rough surfaces usually wear out more quickly

and have higher friction coefficient than smooth surfaces.

Figure 9. Surface roughness tester

The portable surface roughness tester Mitutoyo SJ-210

model (Figure 9) was used to determine the surface

roughness parameters Ra, Rq and Rz. The 2.4-inch color

graphic back-lit LCD provides excellent readability and

an intuitive display. Up to 10 measurement conditions and

one measured profile can be stored in the internal memory.

An optional memory card can be used as an extended

memory to store large quantities of measured surface

profiles and setup conditions. The instrument shows the

measured values in micrometers.

2.7.3. Surface Roughness Parameters

A roughness value can either be calculated on a profile

(line) or on a surface (area). The profile roughness

parameter Ra (Arithmetic mean roughness parameter), Rz

(Average depth of roughness parameter), Rq (Root mean

square roughness) are used during the study.

Profile roughness parameters are shown in (Figure 10).

Figure 10. Surface profile roughness parameters

The various roughness heights of normal cement mortar

plastering and for the plastering with 30 % nano cement

are given in Table 3.

Table 3. Surface roughness of normal cement and cement mortar with 30% nano cement

Roughness

height

Cement

mortar 1:3

Cement mortar with 30 %

nano cement

Ra 5.444 µm 4.884 µm

Rq 6.818 µm 5.958 µm

Rz 32.195 µm 24.056 µm

It is observed from the tables that the roughness height

of cement mortar tiles with nano cement 30 % is less than

that of normal cement mortar tiles. The decrease in

roughness height indicates that nano cement makes the

exterior surface of the spillway smoother. (Ra being 4.884

µm for spillway with nano cement whereas the value of Ra

is 5.442 µm for spillway without nano cement.

The reduction in the average roughness height is

11.53 %.

2.7.4. Porosity

The porosity value of normal cement mortar is

presented in Table 4.


Table 4. Porosity of normal cement mortar tiles

Sl.no

Weight of normal

cement mortar tiles Porosity

(%)

Average

value of

porosity

(%)

Initial

weight

(kg)

Final

weight

(kg)

1 8.95 9.55 6.70

6.770 2 8.31 8.88 6.86

3 7.85 8.38 6.75

The average value of porosity for the normal cement

mortar surface is found to be 6.770 %.

The porosity values of cement mortar with 30% nano

cement is presented in Table 5.

Table 5. Porosity of normal cement mortar with 30% nanocement

Sl.no

Weight of cement

mortar tiles with

nano-cement 30 % Porosity

(%)

Average

value of

porosity

(%) Initial

weight(kg)

Final

weight(kg)

1 8.44 8.72 3.32

3.500 2 8.57 8.88 3.62

3 9.02 9.34 3.55

The average value of porosity for the cement mortar with

30 % nanocement is found to be 3.500 %.

It is observed that the average value of porosity for the

cement mortar with 30 % nanocement is 48.30 % less than

that of normal cement mortar.

The decrease in porosity is found to be 48.30 %. This

indicates that nano cement makes the exterior surface of

the spillway smoother and hence porosity and friction are

reduced facilitating a higher discharge.

3. Conclusions

The following conclusions were derived based on this

research.

Nano material makes the exterior surface of the

spillway smoother and hence porosity and friction are

reduced.

The increase in discharge of spillway with 30% Nano

cement is found to vary from 7.14% to 90.98%.

From the SEM images, it can be seen that the nanosized

particles present in the mortar make the surface smooth

and hence the discharge increases.

It is found that the roughness height of cement mortar

with 30 % nano cement is less than that of normal cement

mortar tiles. The decrease in roughness height indicates

that nano cement makes the exterior surface of the spill

way smoother.

It is observed that the average value of porosity for the

cement mortar with 30 % nano cement is less than that of

normal cement mortar.

The decrease in porosity is found to be 48.30 %. This

indicates that nano cement makes the exterior surface of

the spillway smoother and hence the discharge over

spillway increases.

Acknowledgements

The authors acknowledge research facility provided by

the Department of Civil Engineering, Karunya Institute of

Technology and Sciences, Coimbatore, Tamil Nadu, India

for carrying out the research presented in this research

paper.

REFERENCES

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[2] Bazin, H. E.1888; Recent experiments on the flow of water over weirs, Proceedingl, EngiMel'8' Club of Philadelph.ia, 16 (6): 393-148. Ba.zin's data were reprinted almost eutirely by G. W. Rafter in Report on special water-Supply investigation, Congressional Documents 4146 and 4147, Washington, D.C., pp. 571-950, l990; and Hydrology of the State of New York, 'l'few York State musuem Bulletin 85, Albany, N.Y.,1905.W. Zabierowski, A. Napieralski. Chords classification in tonal music, Journal of Environment Studies, Vol.10, No.5, 50-53.

[3] Chow, V. T. Open-channel hydraulics, McGraw-Hill, New York, 365–380, 1986.

[4] Murphy, T. E. Spillway crest design. MP H-73-5, U.S. Army Engineer Waterways Experiment Station, Vicksburg, Miss., 1973.

[5] Design of small dams, U.S. Bureau of Reclamation, U.S. Government Printing Office, Washington, D.C., 1977.

[6] Maynord, S. T. General spillway investigation. Tech. Rep. HL-85-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg, 1958

[7] US Army Corps of Engineers Waterways Experiment Station., revised in subsequent years, Corps of Engineers Hydraulic Design Criteria, 1952.

[8] Xlyang, J., Cederström, M. Modification of spillways for higher discharge capacity. J. Hydraul. Res. 45 (5), 701–709. 2007.

[9] Arun Joji, Nithya Thomas, Reshma Jose, Yapung Chije, Solly George. Spillway design for a Composite dam, International Journal of Engineering and Technology (IRJET) e-ISSN 2395-0056 Volume: 03, Issue: 04, 2557-2564, 2016.

[10] Mamok suprapto Increase spillway capacity using labyrinth weir, Journal of procedia engineering, volume 54, 440-446, 2013.

[11] Dhaktode Asaram, Gatne Deepankar, Gurjeet Singh, Kasabe Vishal, Kasawa Akshay. Energy dissipation by using different slopes of Ogee spillway, International Journal of


Engineering and General Science, Volume 4, Issue 3, May –June, ISSN 2091-2730,18-22, 2016.

[12] Alaa A. Abdul-hamed, Furhad M. Othman, Noor A. Hmeed. The effects of nano flyash on properties of cement mortar, International Journal of Advanced Engineering Technology, Vol. 9, 1-8, 2018.

[13] Santosh Kumar Garg, Irrigation Engineering and Hydraulics Structures, Khanna Publishers, Revised edition 2010.

[14] ISO4287: Geometrical product specifications (GPS) – surface texture, profile method- Terms, definitions and surface texture parameter (ISO 4287:1997.

[15] Clausen R, Stemgenberg J. Roughness of shot-peened surfaces – definitions and measurement, the 7th

International conference on shot peening, Institute of precision mechanics, Warsaw, Poland, 69-77.

[16] Harinarayan Tiwari. Nayan Sharma. Development to improve hydraulic competence of spillways, Journal of aquatic procedia, Volume:4, 841-846, 2015.

[17] Amir Abbas Kamanbedast, Mostafa Bahmani, Roozbeh Aghamajidi. The effect of surface roughness on discharge coefficient and cavitation of ogee spillways using physical model. Journal of applied science and agriculture, Volume: 6,2442-2448, 2014.

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Integrating Cultural Change Management Program with Smart Workplace Transformation and

Refurbishment Project Schedule

Sefik Emre Ulukan

Faculty of Engineering and Architecture, Istanbul Rumeli University, Istanbul, Turkey

Received July 22, 2020; Revised August 12, 2020; Accepted August 20, 2020

Cite This Paper in the following Citation Styles (a): [1] Sefik Emre Ulukan , "Integrating Cultural Change Management Program with Smart Workplace Transformation and Refurbishment Project Schedule," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 847 - 859, 2020. DOI: 10.13189/cea.2020.080512.

(b): Sefik Emre Ulukan (2020). Integrating Cultural Change Management Program with Smart Workplace Transformation and Refurbishment Project Schedule. Civil Engineering and Architecture, 8(5), 847 - 859. DOI: 10.13189/cea.2020.080512.


Abstract Amongst the current trends in commercial real estate and workplace solutions sector, smart, agile, or digital workplaces that provide flexible and smart working environments have become more important and preferred solution. Globally many companies have been transforming their workplaces into agile workplaces to exploit the benefits including, but not limited to reducing real estate footprint, sustainable & energy efficient operations, improving employee motivation & efficiency, and therefore reducing operational costs. The workplace transformation has a significant impact on employee performance and engagement due to the cultural change it brings along. This cultural change must be well managed across all phases of the project to ensure the success of the workplace transformation. This success criterion is an important performance indicator which, is generally measured as user experience upon completion of the project. To effectively manage this process, cultural change management activities should be integrated with the project, design & construction schedule and linked with the project activities. The objective of this research is to provide a framework program for the cultural change management activities that need to be managed as part of the office transformation and refurbishment projects and integrating them with the project schedule. A focus group study method has been conducted to achieve the objectives of the study. Detailed findings, key change management activities and the framework program have been provided in this paper.

Keywords Office Design and Construction, Project Management, Cultural Change Management, Workplace Design and Transformation, Project Program, Smart Office, Digital Workplace, Agile Workplace

1. IntroductionOver the last 20 years, there has been a rapid and

substantial change in the way that the employees work and the way that the organizations conduct their business. Major developments in technology and the economy had a significant impact on this change. As the work style evolves and changes, workplaces also evolve to accommodate these changes. Especially with the rapid development of technology and global concerns such as economy, environment and sustainability have enabled the development of a new type of workplace that is flexible, agile, productive, user friendly, technological and smart. Businesses started realizing the advantages and importance of transforming the workplaces into an environment that reflects technologies, new & modern work styles and user preferences such as collaboration culture [1].

The evolution of the workplace and work culture has brought several challenges, concerns and risks related with the human factor due to the major change it involves; such as risks related with the end-user satisfaction from project

848 Integrating Cultural Change Management Program with Smart Workplace Transformation and Refurbishment Project Schedule

management success point of view, and productivity issues from a business success point of view.

When a Smart Workplace Transformation Project is being executed, the project manager and the organization should take the impact of the changes in the work environment, work model and organizational culture into account, to ensure the transformation project can be successfully completed. To manage and deliver the projects with the highest user satisfaction, workplace transformation project phases can be supported and improved by the implementation of cultural change management which also eliminates or reduces the associated risks.

2. The Objective of the Study The objective of this study is to integrate the change

management activities with the Smart Workplace Transformation Project.

The study focuses on the integration of ‘Change Management’ activities such as work pattern surveys, workshops, training sessions with the smart workplace project management process, rather than the type of technologies utilized to transform a traditional office into a digital or a smart workplace such as room finding & scheduling system, smart building management system, etc.

3. Methods To achieve the objectives of the study, the evolution and

the need for smart workplaces have been reviewed, benefits of the smart workplaces have been summarized, the need for the cultural change management program has been discussed and integration of the change management program with the project program has been achieved by conducting the focus group method. Finally, the outcomes of the study have been summarized in the conclusion section of this study.

3.1. Agile, Digital or Smart Workplace

In one of the pioneering researches [2] on the evolution and the future of the workplace, the agile workplace has been defined as a workplace “that is constantly transforming, adjusting and responding to organizational learning” [3]. Bell and Joroff [3] also pointed out that, agility in this context means continuous improvement of the work and associated infrastructure, not only the usage of the technology or the physical environment i.e. the building itself.

This workplace transformation and evolution have been significantly impacted by various factors, such as the needs and the behavioral differences of the generations like millennials and generation X. This human factor has acted as a catalyst over the evolution of the workplace. Over the

last 2 decades, a vast number of research and studies have been conducted to identify the behaviors of each generation group and how to adapt the workplace to meet with the needs of different generations. Some of the researches focused on millennials, considering that the millennial workforce was anticipated to reach up to 50% of the workforce by 2020 [4], which led the designers and businesses to put more focus and priority on adapting the workplace to meeting the needs of the millennial workforce. On the other hand, recently there are arguments against this trend claiming that the workplace should be designed for all generations [5], not just for millennials or upcoming new generations. These studies highlight the importance of designing the workplace in a way that drives the interaction and knowledge transfer between the generations to enhance the productivity of the workforce.

As the Industrial Age has transitioned into the Digital Age, the technology element of the agile workplace has developed even more rapidly. While 'Agile Office' term has been commonly used by the academic world and industry, 'Digital Workplace' and 'Smart Workplace' concept or terminology has also started being used for describing ‘digitally and technologically enhanced agile workplaces’. This is mainly due to the breakthrough developments in the wireless communication technologies, digitalization of documents and processes, and developments in collaboration tools and technologies such as, high tech audio-visual tools, internet of things as well as intelligent systems & equipment such as Smart Building Management Systems, that control the building in a way to provide a functional and comfortable office environment, which in turn improves the employee experience. Utilization of these smart technological tools and equipment, together with the agile workplace principles led to the design of workplaces being transformed into digital or smart workplaces.

‘Digital Workplace’ term is typically used to describe the workplace as a set of tools that are transforming towards a digital environment. Deloitte [6] defines the DWP as - “The digital workplace encompasses all the technologies people use to get work done in today’s workplace – both the ones in operation and the ones yet to be implemented”. Following this definition, they refer to tools & technologies such as HR and business applications, instant messaging and emails, social media and virtual meeting tools. Robertson [7] on the other hand, widens the definition of digital workplace as 'holistic set of tools, platforms, and environments for work, delivering in a coherent, usable and productive way’ by adding the ‘environment’ into the description. In several research studies, authors such as Bakar et al [8] and Williams & Schubert [9] generally focused on the technology part of the digital workplace as some of the technology companies and software developers are using this term to describe their products or services such as IBM [10], Microsoft [11] and many others. Therefore, ‘Digital Workplace’ term may


be confused with technology-based work platforms, products or services, in other words, the software and application-based solutions. Perhaps ‘Smart Workplace’ would be a better way to describe the technologically enhanced agile offices as it refers to the agility of the physical workplace, efficiency-driven processes and extensive use of smart and highly developed technology.

Regardless of which terminology is used, in a broader context, a smart workplace describes not only some high-tech tools or systems, but a holistic perception of flexible, adaptable, technologically enhanced work environments and processes that promotes productivity, collaboration and innovation.

3.2. Benefits of Smart Workplaces

Economic developments over the last 30 years have given rise to the emergence of ideas and initiatives, such as environmentalism, sustainability and cost-efficiency, to name a few, which have contributed to the acceleration of the workplace evolution. This evolution and transformation have not only enabled workplaces to become more efficient and productive, but also helped with the introduction of a new type of business and workplace models such as co-located offices where several different companies share the same office or common parts of the office, and where the workplace is designed to support maximum agility and utilization of technology. While the workplace and technology were evolving and transforming into a new model, these developments have encouraged many businesses to start harnessing the benefits of agile & smart workplaces. Gartner's research [3] - one of the earliest comprehensive studies in this area – pointed out that some of the multinational companies have already started transforming their offices in the late 1990s and early 2000s.

While many of the technology and multinational companies quickly adapted and implemented the agile/digital/smart workplace designs and standards, some industries or companies haven’t shown the same level of willingness or agility to implement the new smart workplace concept due to various different reasons such as, financial status, culture or size of the company. However, more & more companies are now realizing the benefits of the agile/digital/smart workplaces, where it becomes a viable business case, especially linked with corporate responsibilities and ideals such as sustainability, environment, productivity and profitability. Benefits of smart workplace include; Increased employee productivity [12] Increased employee satisfaction [13] Talent Retention & Talent Attraction [14] Improved employee motivation and engagement [15] Increased efficiency by easy access to information

and retaining company know-how resulting with significant cost savings and increased profits [16, 17]

Footprint reduction & sustainability as a result of the optimized space as well as fewer building materials and less initial capital investment

Cost savings from the lease, maintenance and operational costs

Increased health and wellbeing and reduced absenteeism by flexible working and working from home [18]

Improved processes and employee skills by using digital tools and high-tech equipment which also boosts creativity & innovation

Better customer service and client satisfaction by highly engaged and motivated employees

According to the studies by Deloitte [6], Avanade [17], Van der Voordt [19], further potential benefits can be summarised as; Higher problem-solving capacity Positive image for the employer Improved accessibility Better teamwork Breaking down silos in the organization by

collaboration

While the majority of the studies focus on digital technologies needed for creating a digital workplace, it is also equally important to provide necessary physical infrastructure, environment and ‘look and feel’ for the smart workplaces. This could be achieved with an effective ‘smart workplace design’ and an effective ‘project management’ that, harmonize all those technological and physical elements as an integral part of the workplace.

3.3. Cultural Change Management for Smart Office Transformation

While the work and the workplace are transforming, the workforce is also changing. As baby boomers and generation X are retiring, millennials are taking over the majority in the workforce. According to a report by Pew Research Center [20] based on the US Labor Force statistics, millennials have become the largest generation in the US workforce in 2016 by reaching up to 56%. This transformation comes with challenges. The major challenge is that organizations and people cannot change as quickly as technology or the workplace.

The differences between the generations such as, the level of skills and knowledge and familiarity with the technology or the way of doing business, create difficulty with developing a workplace design suitable for a multi-generational workforce. This difficulty significantly increases during workplace transformations. Employees may have a different level of interests, concerns or hesitations for the upcoming changes. In addition to the emotional challenges of employees, a smart office transformation requires - time, a major cultural change to accommodate all the changes in the way of conducting


business, the technologies used in the workplace and finally, how the people collaborate. Employees are expected to develop new skills while they are coping with emotional stress and this is where Change Management comes into play.

Figure 1 represents the Change Curve model developed by Elisabeth Kubler-Ross [21] which illustrates the emotional reaction of people upon experiencing a life-changing event. Once the change starts, then the frustration and depression cause a major plunge of performance and competence within the organization due to the emotional reaction that the employees experience.

To avoid or reduce the impact of the negative emotional reaction that employees experience when they hear about the upcoming change i.e. the workplace transformation, a change management process needs to be implemented. Change management helps with the simultaneous development and implementation of the new work processes, necessary skills, technological tools, physical environment and the new work culture needed to make a productive start in the new workplace.

One of the critical success factors of the smart workplace transformation project is to achieve maximum employee experience and satisfaction at the end of the transition. Therefore, employee’s engagement, contribution, collaboration and buy-in are vital for a successful implementation. This can be also achieved by the change management process.

Prosci [22] defines change management as 'processes, tools and techniques to manage the people side of the change to achieve its required business outcomes'. It is about managing employee engagement and adopting organizational changes in a systematic way. A common method used for organizational change management is ADKAR model which is an acronym for each milestone of the process, i.e. "Awareness, Desire, Knowledge, Ability and Reinforce", developed by Jeff Hiatt at Prosci. Hiatt & Creasey [23] define ADKAR method as a model framework to look into managing individual changes and individual transitions. As the smart workplace transformation is more than just an organizational change, it needs to be integrated with the phases of the transformation program and customized to address the challenges arising from a complete change of the work environment. Therefore, the ‘workplace cultural change management’ efforts should be integrated with workplace transformation project processes and phases.

For this purpose, 5 milestones of ADKAR change management model have been integrated and overlapped with the 5 basic phases of a workplace transformation and fit-out project. Figure 2 illustrates ADKAR model and the 5 simple phases of a workplace transformation and fit-out project overlapped with Kubler Ross Change Curve Model to apply them to the Smart Workplace Transformation project.

Figure 1. Kubler-Ross Change Curve Model


Figure 2. Kubler Ross Change Curve Model applied to Smart Workplace Transformation (Developed by Author)

Figure 3. Phases and summary tasks of a Digital Workplace Transformation project program. Subtasks are collapsed due to the size of the program. (Developed by Author)


3.4. Methodology

In order to achieve the objectives of the study, a focus group method has been used. However, in order to conduct the focus group session, the framework of the model has been adapted. This framework is based on the model explained in the Change Management section of this study, which consists of the integration of ADKAR Change Management model with Kubler Ross Change Curve Model and with the 5 basic phases of a fit-out project as illustrated in Figure 2.

For integration purposes, the main project schedule is based on a real-life example of comprehensive office relocation and a smart workplace transformation project schedule. The project schedule has been prepared in

Microsoft Project. The schedule for each phase of the project has been highlighted in a different color in Figure 3.

Including the real estate market search period, all process is anticipated to take approximately 500 days. The duration of the project hasn't been considered as a challenging area and optimization of the schedule could be an area for a future study.

Following the creation of the main project schedule, change management activities have been identified for each phase in accordance with ADKAR milestones which need to be achieved at each phase. These change management activities and their purposes have been illustrated in Figure 4. In order to integrate the change management activities with the work program, the focus group interview has been organized.

Figure 4. Change Management activities identified for Digital Workplace Transformation (Developed by Author)

Phase Activity Purpose

Aw

aren

ess

/ In

itiat

e Leadership Engagement Communicate Need for Digital Workplace & Change Management Awareness for Leadership about the DWP project management process

Provide awareness to leadership team on how the DWP project shall be managed

Develop Basic CM Plan Define Key stages & activities, success criteria Utilization Study To determine current use of the workplace, tools & equipment Employee work pattern survey Understanding current work pattern and DW requirements IT Systems Assessment Evaluation of current IT systems platforms & tools and GAP analysis Employee Town Hall Communication with Employees creating initial awareness Engagement

Des

ire

/ Pl

an

Key Stakeholder Engagement Involve Leadership team for each stage of the project Select and Onboard Change Champions

Selection of the OCC team to engage/ onboard on R&R ad project next steps

Employee Engagement Employee engagement to the project Employee Envisioning / Deep dive about DWP

Share potential changes, benefits and uses of DWP with employees

Onboard Change Champions Onboarding Change Champions for their role Deployment of survey results Identify organization’s needs Benchmark Discover best practices in the market and benchmark Employee Envisioning Surveys Collect feedback from employees about their dream workplace Define Vision Definition of vision

Know

ledg

e /

Des

ign

Scope Definition Meetings What and How would be the new workplace setup Special needs by organization

Communication Plan Announcement Kick-off engagement of the organization Setup Communication Tools Special mail address, Newsletter Design Activities Action Plan definition with Main initiatives, Positive campaign Design IT and Technologic Tools Design the tools, equipment, systems, platforms Design Review Meetings Review designs with teams

Abi

lity

/ Co

nstr

uct

Setup Communication Tools Special mail address, Newsletter Cultural Interventions Go Digital (Paperless), Digital Trainings, Move Training Welcome Pack Provide a welcome kit for engagement and also with needed

information to a smooth transitions Implement IT Systems Implementation of IT systems & platforms Move Day Activities Develop Plan for move day organization

Rein

forc

e /

Clos

e

Learnings and Critical points Identify key learnings & action plans Post Move Survey Measure employee satisfaction Hypercare for new tools & equipment Support employees for the new system & tools Reinforce messages & Make it sustainable

Start Operation & Continue Reinforcing messages,

CM toolkit for Continuous Development & Onboarding

Toolkit developed for future onboarding of new employees and new leaders


3.5. Focus Group Study

Focus group method has been an increasingly popular qualitative research method not only in academia, but also in business as well [24]. The focus group has been defined by Krueger and Casey [25] as 'a carefully planned series of discussions designed to obtain perceptions on a defined area of interest in a permissive, non-threatening environment'. The use of the method dates back to mid-1920's however, it has become more popular within the last 20-30 years [26]. This is because the focus group method provides advantages such as; Being an efficient way of collecting a large amount of

data in a short time [25, 26, 27] Ability to collect particular opinions, attitudes or

different perspectives of participants [28] Ability to enable the researcher to attain in-depth

insights into the researched topic [27] Ability to obtain information about their expert

opinion from the participants

Therefore, the focus group method has been identified as the most suitable method for this study in order to obtain expert opinion on the identification and integration of change management activities.

Another important point in the focus group method is the size of the group. In his research, Masadeh [24] has reviewed and summarized suggestions of some authors and scientists and advised that the number of people in a focus group could be between 4 and 12 and in some cases, it could be even between 10 to 31 depending on the type and purpose of the study. In terms of the duration of the focus group session, Masadeh [24] also summarized the opinions of various researchers varying between 30 minutes to 3 hours.

It is obvious that the subject and the objectives of the research should be the main drivers determining the number of participants and the duration of the focus group session for the effectiveness of the study and quality of the data.

4. Findings and Discussion In order to achieve the objectives of the Focus Group for

this study and to collect reliable and quality data, 5 professionals have been identified and invited to a 1 hour 30 minutes session, who have been responsible for managing workplace fit-out projects, designs, facility

management operations at multinational companies as well as managing the fit-out operation as general contractors, who have been involved in and experienced with workplace transformation and fit-out projects. Selected participants have also been involved in the change management activities in such projects. Therefore, all participants have experience with the subject. Therefore, participants of the focus group have been invited were; A Project Manager at a multinational real estate

company, A Facility Manager of a multinational real estate

company Workplace Designer & Design Manager of a

multinational real estate company General Manager of a contractor company whose

expertise is fit-out and delivery of workplaces for multinational companies

Construction Manager and Director of the same contractor company

Upon development of the detailed project schedule, the change management activities have been integrated with the project schedule as a draft version in order to use the time efficiently during the session. Figures 5-8 illustrate the part of the work schedule and the integrated Change Management (CM) activities. Then the focus group session has been organized where the author of this study acted as the moderator. Following the introduction, participants have independently shared their opinions and perspective on the project schedule, advised the CM activities for each phase, recommended necessary changes in sequence and timing of CM activities and any additional activities that might have been needed.

During the session, the participants have stressed the importance of implementing the change management process during a smart workplace transformation project especially involvement at the earliest stages of the project. This is because the important strategic decisions are made and communicated at the earlier stages and a structured change management program or strategy would significantly support the initial activities and increase the effectiveness of the transformation from the beginning. It has been also highlighted that employee engagement at the planning and design phase is very important in order to achieve buy-in of the employees. Getting the employee buy-in would significantly improve the success of the change management process therefore the success of the smart office transformation.


Figure 5. Change management activities integrated with project schedule - Summary of Activities 1-76 (by Author)







5. Conclusions The processes and cultural change management

activities may differ from one project to another depending on whether the project will be a workplace relocation or a transformation within the same premises. Also, the scope of the project, the number of process changes and the extent of the technology transformation and implementation will have an impact on the extent of the change management activities.

Although the cultural change management activities may be added or removed or shifted in between the phases, the model can be considered as a framework program for the smart workplace transformation project. The time spent on the activities may raise concerns in terms of the overall delivery date of the project, however, optimizing the duration needed for each activity may be another study area. On the other hand, focus group pointed out that if the Change Management activities start on a timely manner and are coordinated in parallel to the project activities, the time impact wouldn’t be cause for concern and the benefits of implementing change management would exceed the cost or time impact. Further advice based on the experience has highlighted that successful

implementation of the change management significantly increased the scores received from user experience surveys.

One of the most important outcomes of the focus group session has been the advice from the Facility Manager to implement the final phase of the change management process as an integral part of continuous development plans of the facilities operation. All projects need to be closed out once their lifecycle ends, however, it has been found out that the change management process should not end with the project closure and further CM activities should be part of the standard operating plans of the company to ensure the transformation is sustainable.

This initial report aims to provide the preliminary outcomes of the research. A forthcoming detailed report is anticipated to provide further details on the outcomes of the research and details of the model.

Acknowledgements We are very grateful to the experts for their appropriate

and constructive suggestions to improve this template and for the focus group participants for their contribution to


the research. The preliminary findings of this research have been

presented at the 3rd International Conference of Contemporary Affairs in Architecture and Urbanism, ICCAUA 2020

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of Interests

The author declares no conflict of interest.

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Assessment of Quality of Life in the Urban Environment; Case Study: Famagusta, N. Cyprus

Mojdeh Nikoofam1,*, Abdollah Mobaraki2

1Department of Architecture, Faculty of Architecture, Eastern Mediterranean University, Turkey 2Department of Architecture, Faculty of Fine Arts, Design and Architecture, Cyprus International University, Turkey

Received July 22, 2020; Revised September 13, 2020; Accepted September 19, 2020

Cite This Paper in the following Citation Styles (a): [1] Mojdeh Nikoofam, Abdollah Mobaraki , "Assessment of Quality of Life in the Urban Environment; Case Study: Famagusta, N. Cyprus," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 860 - 872, 2020. DOI: 10.13189/cea.2020.080513.

(b): Mojdeh Nikoofam, Abdollah Mobaraki (2020). Assessment of Quality of Life in the Urban Environment; Case Study: Famagusta, N. Cyprus. Civil Engineering and Architecture, 8(5), 860 - 872. DOI: 10.13189/cea.2020.080513.


Abstract Nowadays, the quality of life in urban environments is a controversial issue discussed in different studies as a response to many recent problems faced by cities around the world. This issue has been the center of discussion in different studies given that, based on tangible and intangible characteristics of human life. It has become one of the main concerns of every society. Since people carry out different responsibilities in urban environments, an assessment of city life is of major importance. Given that urban planning significantly impacts human health and the level of satisfaction, the study is aimed to assess the quality of life in the urban environments based on subjective and objective indicators that can be applied to improve health communication and urban vitality. For the purposes of this study, urban life in the city of Famagusta, as the most important city of North Cyprus, was investigated according to the quality of life indicator.

Keywords Quality of Life, Subjective Indicator, Objective Dimension, Urban Environment

1. IntroductionGiven the multidimensional feature of the concept of

quality of life defined in different fields and the complex implications it carries, it must be investigated using different approaches and from various theoretical viewpoints. Quality of life encompasses environmental, social, physical, economic, and psychological welfare and

different experts in different fields have always attempted to handle the issues in various contexts [1]. On the other hand, the measurement of the issue is not a contemporary concern. A long time ago (384-322 BC), the philosopher Aristotle who wrote about “Living-well” and “The Good Life”, also assessed that public policies are able to improve the concept. Also, considering the concept creates high competitiveness between different urban planners. Quality of life focuses on social indicators, civic livability, quality of communications, and psychological indicators, all subcategories of healthcare in the field of urban planning. When an urban designer wants to increase QOL, they generally try to define the external indicators including the level of individuals’ income, good access to essential services and local resources, rather than consideration the internal conditions [2]. D. J. Forkenbrock and G. E. Weisbrod, [3] stated that urban planners make an attempt to create a healthy community and livable city by: Enhancing physical activity of people, Granting easy access to different forms of

transportation, education, work, housing, healthy food, and green spaces,

Using of clean air and water, Availability of chances for recreational and leisure

activity, Improving visual characteristics of spaces, safety, and

sense of belonging, Conservation of agricultural lands, wildlife and

natural resources.

The immigration forms and attempts to increase


urbanism directly affect QOL so the governance, urban planners and other relative communities tried to support the differences by applying the nature of job opportunities and the competitiveness of urban areas [4]. It is obvious that there is a very close relationship between QOL and the context of the urban environment where people are living. In order to determine the quality of life in the urban environment, the conditions of the environment should be measured according to the applied indicators. Additionally, if those conditions have been changed over time, it should be considered whether the changes have had an improving or deteriorating effect on QOL. People make various

subjective opinions about the things which influence the quality of human life in their urban surroundings because different people might have different perceptions of this concept. Thus, the assessment of QOL in the urban environment is taken into careful consideration by various professionals in different fields especially those in urban planning. As illustrated in Figure 1, the study has designed based on subjective and objective dimensions and develop widespread relative indicators in order to assess QOL in the urban environment. Also, the assessment is examined in the case study of Famagusta.

Figure 1. Structure of the Paper

862 Assessment of Quality of Life in the Urban Environment; Case Study: Famagusta, N. Cyprus

1.2. Quality of Life

QOL is an extremely general phrase that can have various meanings for different persons and covers different realms [5,3]. Based on P. L. Rosenbaum et al., [6], the quality of life includes three main areas that are: 1) Being refers to the physical, spiritual, and psychological components, 2) Belonging make connections between humans and social, physical, and community environments, and 3) Becoming refer to daily activities and participation in order to achieve hopes, aims, and leisure aspects. Quality of life is a multidimensional issue which is considered in a wide-range of professions, such as economic, psychological environment, urban planning, healthcare, and other fields. QOL is related to the level of individuals’ happiness, and their satisfaction of different life aspects such as occupation, home, community, life, and society; as well as their economic, family, spiritual, leisure, social, emotional, and psychological well-being [7]. R. Keles [8] stated well-being reflects not only individuals’ life, but also the perception of people about their lives in the area. The QOL is measured at two different levels, the individual scale and the collective or community scale. The individual scale assesses the basic requirements and expectations and the level of individuals’ satisfaction about the available amenities and services. Furthermore, the collective level refers to the indicators which improve the quality of life in societies. It should be mentioned that there might be less difference in the level of satisfaction on the scales, in various communities. World Health Organization defined quality of life how humans feel about their position in life based on their culture and the value organization in which they live and how well they can achieve their expectations, targets, concerns, and standards [9].

1.3. Quality of Life and Sustainable Development

According to G. Moser [10], QOL as a dimension of

urban planning is one of the fundamental principles of sustainable development because sustainable development is able to satisfy the requirements of the current generation without ignoring the ability of future generations to achieve their own essentials. Therefore, the achievement of individuals’ requirements is not only, a precondition for sustainability, but also, creates human well-being which is one of the most important aims of achieving a high level of life quality. Environmental, social, and economic dimensions are considered to achieve sustainable development while at the same time supporting unpredictable future needs as well. Thus, the concept of QOL has a very close relationship with sustainable development that creates a balance between the dimensions which have a fundamental influence on quality of life in different scales. Sustainability should not only, ensure environmental well-being by establishing a relationship between users and the environment, but should also, ensure enhancement of individual and collective well-being. Conventionally, quality of life has been related to four issues of relative psychological study and public strategy that are: the level of individual satisfaction, health, the objective indicators of living, and sustainable development [11]. Sustainable development cannot be attained without the achievement of objective and subjective indicators of QOL.

The ideological attempt of the QOL is to improve resources for people in their surroundings to live in the best way. However, sustainable development can negatively or positively impact individuals’ quality of life because while some sustainability issues are accepted by some individuals, they could be considered as unacceptable for other members of society. Consequently, it should be considered which principles of sustainable development could be acceptable for the issue. Also, when the policymakers implement the development, they should have careful attention to the potential impact it could have on some of the most fundamental indicators of QOL.

Figure 2. The Concept of QOL Has Highly Close Relationship with Sustainable Development


1.4. Quality of Life and Urban Environments

The researchers in social science and the environmental planning professions have been investigating the quality of life in the subjective and objective dimensions. Urban environment can be defined as having unbuilt or natural, built or physical, and intangible or socio-cultural dimensions [12,13]. Additionally, different environments have allocated various characteristics to each dimension. Although, studies about quality of life have tried to consider the individuals’ attributes, for example, their occupation, health, age, and human relationships. People are spending their lives in places with particular characteristics which are formed based on that specific environment, which might be limited at different levels or scales such as a housing unite neighbourhood or local district, a metropolitan, and a state. Therefore, people’s living environment can have an important influence on their quality of life according to their characters, scales, etc. In order to design an urban environment that would enhance the level of satisfaction for the users, the urban planners initially examine the connection between urban environment and the received quality of life. People have different perceptions about life in an urban environment and the level of perception reflected quality of life for its residents. Many urban studies indicate the important characteristics of urban environment for achieving the positive contributions which increase the quality of human life in their environment. For instance, in order to improve the quality of human life, contemporary approaches of urban planning are applied to serve the most important requirement of the people who are living and working in that environment [14-16]. J. I. Carruthers and B. Mundy [17] considered the New Urbanism (NU) that was established by a group of different scholars in Congress for the New Urbanism (CNU). They tried to create friendly pedestrian environments in neighbourhoods to decrease car-dependency by using “Transit-Oriented Developments” (TOD) and “Neo-traditional Town” as the main theories for the movement. The main goal of this movement was achieving a high quality of life by applying the principles listed below [14,18,19]: Well-structured cities, and neighbourhoods with well

distinguishable centres and edges, Interconnected streets with friendly sidewalks and

cyclists, suitable and adequate parking spaces and garages to avoid car-dependency,

Compact development in order to protect farmland, wildlife and environmentally sensitive areas (survive biodiversity),

Designing mix land uses instead of single use and segregated functions (mix of activities),

Creating a variety of housing typologies and street to create a coherent urban form,

Constructed well designed civic constructions and public gathering spaces,

Improving the quality of greens or parks and their conservation to connect and define neighbourhoods and cities with an increased sense of belonging,

Respect to local history and regional character with well architectural design.

In order to develop quality of human life in the urban environment, New Urbanism can achieve different indicators of quality of life by using the principles illustrated in Figure 4.

In addition, Smart Growth (SG) is a movement focusing on promoting compact design, diversity, and walkability to decrease car-dependency and land-consumptive. As can be seen in Figure 3, the most prominent indicator of the movement is improving quality of life. As it is mentioned by Song Y. and G. J. Knaap [20], Smart Growth is able to increase the quality of life by adopting community, economy, and environment without ignoring all traditional theories.

The movement attempt to define all indicators of QOL according to the listed principle (See Figure 4). They tried to achieve the environmental characteristics by protecting open spaces, farmland or natural properties and critical environmental areas [21]. Also providing advantages from adopting compact building design, well-organized infrastructure and mixed land use are applied as physical characteristics to achieve quality of life. Moreover, the movement is based on walkable trails and different range of transportation choices to increase the level of urban mobility in cities. In addition, fostering diversity and creating attractive communities with a strong sense of place-attachment for all users provide social justice and psychological indicators which increase the level of quality of human life in urban environment [14,22-24]. The pioneers of Smart Growth decided to develop decision-making about urban legislation to improve cost-effectiveness, and equal rights in political and economic theories for enhancing QOL in urban surrounding [14,22,25]. Therefore, the mentioned example illustrates that the design of the urban environment has a different influence on various settlements. The designers always with an excellent design try to increase economic stability, social health and being responsible toward environmental and natural properties throughout suitable policies or good governance which have a fundamental impact on quality of individuals’ life.


Figure 3. The Goals of Smart Growth

Figure 4. The Relation between the Dimensions of QOL and the Principles of NU and SG


2. Investigating Quality of Life in Urban Environment

Two main approaches are defined by E. Diener and E. Suh [26] to measure the QOL. The first approach refers to objective indicators which are measured according to the social characteristics of the society, for example, the level of individuals’ education, crime statistics, and the rate of unemployment. The second has measured the subjective indicators which are related to the individuals’ experience about their life, well-being and life satisfaction or persons’ happiness. In addition, R. W. Marans and R. Stimson [27] measured QOL according to the following approaches: 1) The objective approaches, connected to social indicators study. This approach is limited to analyzing aggregate information at different geographic locations collected in official governmental documents, including the census; 2) The subjective indicators provide individual or disaggregate data which focus on the peoples’ evaluations, or assessments of QOL in general, as well as, the assessment of urban environments in particular; 3) The behavioral indicators include space utility, and the availability of participation, facilities, and amenities in our environment (Figure 5).

Moreover, as it is revealed in Figure 5, quality of life in urban environments is investigated based on connecting

different main dimensions including a) environmental characteristics, that refer to the natural aspects of the districts or neighbourhood; b) physical characteristics, that refers to land use management, urban context, facilities or amenities, and infrastructure; c) Urban mobility, which encompasses accessibility, transportation and traffic issues; d) Social characteristics, which contain the indicators related to individuals’ interaction, and participation of citizens ; e) Psychological indicators which discuss the feeling of citizens towards their environment like the sense of belonging or identity; f) Economical characteristics, that refer to the economic indicators in cities like measurement life cycle of cost; and g) political dimension, that related to the urban policies which are able to support the dimension of QOL in urban environment [25].

The present study has defined the quality of life in two dimensions. The objective QOL falls under nine categories of indicators consisting of social, environmental, economic, physical, cultural, political characteristics, urban mobility, infrastructural indicators, and demography (Figure 5, Table 1) [25,28-31]. In addition, the objective indicators are the visual characteristics and place identity or perception of urban space, also, social characteristics can define as both, subjective and objective indicators (Figure 5, Table 1) [28,30-32].

Figure 5. The Present Study Has Defined Dimension of QOL in Urban Environment Based On Different Studies


Table 1. The Indicators and Principles of QOL in Urban Environment Q

UA

LITY

OF

LIFE

Obj

ectiv

e In

dica

tor

Environmental or Natural

Characteristics

Air Quality: Quality of atmosphere, The health quality of air, Prevention of air pollution

Water Quality: Quality of drinking water, Quality of water edges, Management of water consumption

Land Quality: Remediation of soil contamination, Biodiversity, Ecological footprints

Quality of Materials: Renewable, Recycle and Non-hazardous materials with respect to health of people and environment

Quality of Urban Environment: Providing parks & natural landscape, Comfortable outdoor temperature, Decrease sound pollution, Well-lit public open spaces, and Reduction of unpleasant odor

Energy Use: Use of Renewable energy, Energy efficiency

Recycling & Waste Management: Waste collection and disposal, waste recycling

Physical Characteristics

Land Use Management: Mixed land use, Urban facilities and amenities, Effective land-consumptive like land reuse

Urban Form: Compact city, Density

Urban Layout: Street & square network, Building block and proportion (building line, well integrated car parking, building height-to-width ratio)

Quality of House & Building: Building & Housing quality according to durability, adaptability, different type of houses, condition, overcrowding average, access to indoor facilities, access to infrastructure

Quality of Urban Mobility

Accessibility: Pedestrian quality, Connectivity, Movement with respect to the users’ ability

Walkability and Cycling: Walkable network, Cycling ability of network and facilities, Traffic calming

Public Transportation: Available choices of transportation, Adequate and accessible transportation, Easy access to the facilities

Traffic Load: Traffic congestion, Management of transportation demand (TDM)

Cultural Characteristics

Cultural Activities: Number of libraries, museum, theaters Cultural Heritage: Conservation of historical environment

Infrastructural Indicators Availability of health centers, clinics, hospitals and sanitation

Demography Measuring the number of older and youth people

Immigration statistics Rate of population

Economic Characteristics

Affordable Housing, Easy Access or proximity to health center, employment, education, all services.

Energy Cost Land Capacity: balancing the cost differences between land values and individual income,

Passive Solar System: Passive solar heating system, natural cooling techniques and systems for natural lighting create comfortable temperature and decrease life cycle of cost.

Political Characteristics

Urban Strategies & policies, Urban fair rights,

Responsive urban legislation, Strong urban management

Steady supervision

Social Characteristics

Social Justice: Equal access to affordable building, Equal access to all services

Inclusive Communities: Accessibility for disable people, Comfort, Safety

Social Participation: Considering users in Planning process, Increasing diversity.

Subj

ectiv

e In

dica

tor

Social Characteristics Behavioral Performance: Public awareness, Urban stability, Urban vitality

Place Identity

Urban Image: enhancing urban legibility such as constructing landmarks, distinguishable paths and district

Responsive Design: Respecting to the identity of the specified city or district, Protecting of heritage and historical sites such as contextual design

Personalization: Indicating the function of a space, Applying the excellent design that users can adapt with their environment

Visual Characteristics

Urban Attractiveness

Urban Distinctiveness

Management and Maintenance


2.1. Objective Indicators

These indicators are underpinned on quantitative data of urban environment indicators which are reflected in the fundamental requirement of the citizens and enhance the quality of urban life. Environmental or natural properties are the central concern of urban planning that can contribute to the enhancement of human health in urban life (See Table 1) [33,34], because the indicators increase the quality of the air we are breathing, our drinking water, organization of our habitat and the land we are living on. Quality of the air is the essential consideration in urban areas for human health. In order to improve the quality of air, World Health Organization (WHO) has determined the atmospheric quality with decreasing six air pollutants such as CO2, CO, SO2, NO2, O3, and etc [35]. These gases have a high tendency in air pollution and increase urban health. Hence, air pollution leads to different types of dangerous diseases, making short life expectancy, and increasing the rate of death in cities. The health quality of air is suggested because air pollution has become one of the main causes of many problems and a threat to human health in recent years. Consequently, the prevention of air pollution becomes the central concern of urban policies. Thus, the provision of landscapes, plants, trees and green buffer areas can not only, decrease air pollution and increase O2, which we are breathing, but also, provide a suitable bed for health communication and activities [36]. The quality of water is another important indicator that has a significant effect on human health. The quality of drinking water, quality of water edges and management of water consumption is considered to increase the quality of water (Table 1) [30,31]. Furthermore, quality of land can be increased by regenerating contaminated ground, increasing biodiversity, and ecological footprint (Table 1) [30,37]. Other factors which have a deep impact on our environment are attributed to the quality of materials. The materials should be considered according to their impact on human health and health of environment so designers should select non-hazardous, renewable and recyclable materials (Table 1) [36,37]. Moreover, assessment of the local environment is a fundamental indicator in urban planning that can support comfortable conditions in outdoor spaces hence, leading to an increase in the individuals’ participation (Table 1) [31,38]. Providing natural landscapes and parks, comfortable outdoor temperature, decreasing sound pollution, well-lit public open spaces, and reduction of unpleasant odor are the important factors that enhance the quality of local environments (Table 1) [30,40]. Controlling energy use is the other indicator that has a positive effect on environmental and economic characteristics. The final indicator is waste management and recycling. Waste contains solid, gas and liquid nature that can affect human and environmental health (Table 1) [30,31,37]. The second indicator of quality of life is related to physical characteristics. This indicator enhances human activity and communication in urban environments. The

principles of the indicator consist of (Table 1): a) Considering land use management by increasing mixed land use, the urban facilities and amenities, effective use of land like land reuse; b) Considering urban form for optimizing density; c) Making attention to urban layout such as proportion of building block, street and square network; d) Considering the quality of housing and building by increasing adaptability, durability, access to indoor facilities, access to infrastructure and different types of residential units [25,31,37,41].

The third indicator is related to the quality of urban mobility which encourages people to travel and participate in socio-cultural life or activities. The indicator of the characteristics is listed in following: 1) Accessibility increase pedestrian quality, connectivity, and movement with respect to the users’ ability; 2) Walkability and cycling in urban networks; 3) Public transportation: increasing choices of transportation, adequate and accessible transportation, easy access to the facilities; 4) Traffic load is the other factor that has a deep effect on the human well-being (Table 1) [30,39,42]. Cultural characteristics are the other indicators of QOL. The number of libraries, museums, and theatres as cultural life activities and conservation of historical environment as cultural heritage can reflect the QOL in the urban environment (Table 1) [29,43]. Measuring the infrastructural indicators of the society is another subjective indicator that has a fundamental impact on the quality of life in built environments. These include the number of health centers, clinics, hospitals and levels of sanitation (Table 1) [29]. Furthermore, measuring the number of older and youth people, immigration and rate of population as demographic consideration is the most important indicator that should be considered in the urban environment to provide suitable facilities to enhance QOL in the area (Table 1) [27,29]. The sixth indicator is related to the economic consideration which provides information regarding job opportunities and local businesses (Table 1). As can be seen, the situation of urban economic has a significant influence on designing the exterior and interior of the built environments [44]. On the other hand, the designer has a deep effect on the indicator for their user by improving affordability in various scales such as improving proximity and easy access to primary and essential needs such as school, health center, job and all urban services, affordable housing, and decreasing energy cost in buildings by considering energy use because all persons should have fair right to access to these essential [30,37,45]. Also, land and rent price has a deep effect on low- and middle-income households that land capacity improves the balance between land values and income level of people. Moreover, the use of passive techniques for natural cooling, heating, and lighting is the main aims of passive solar schemes that improve comfortable temperature and lessening cost of life cycle (Table 1) [30,45]. In addition, governance and political concern is the most important factor in achieving higher level of life


quality (Table 1) [25,31,48]. The urban policies or strategies, urban fair rights, responsive urban legislation, strong urban management and steady supervision are the most important parameters for enhancing QOL as political characteristics. Additionally, the last indicator can be defined as both, subjective and objective indicators because the social characteristics can reflect quantitative and qualitative indicators (Table 1) [30]. Consideration of social indicators increases social equity and justice, inclusive communities, livability, social interaction and social connectedness in the cities (Table 1) [30,31,39,46-48].

2.2. Subjective Indicators

The subjective indicators of QOL focus on perception, level of human satisfaction, well-being, opinions and feeling of individual and community scale of human beings [26,32,49,50]. The study defines subjective indicators by enhancing the sense of belonging or place-attachment and considering visual characteristics. Identity of place is one of the important proposes of creating a vivid street to satisfy all users and provide means of cohesive communication. The principles of sustaining place identity are related to (Table 1): Consider urban image for enhancing urban legibility

such as constructing landmarks, distinguishable paths and districts;

Responsive and contextual design for respecting to the identity of the specified city or district and protecting of heritage and historical sites;

Personalization by indicating the function of a space, applying the excellent design that users can adapt to their environment.

Visual characteristics of a place can have a deep effect on quality of life in the environment [51,52]. The principles

of the characteristics are: 1) urban attractiveness; 2) urban distinctiveness; 3) management and maintenance are the other responsibility for enhancing urban morphology (Table 1). The above-mentioned principles can increase cleanliness, comfort, safety and inclusivity in our environment that the indicators have a fundamental influence in enhancing the quality of urban life by increasing community and urban livability.

3. Case Study Famagusta is the second largest town of Turkish

Republic of Northern Cyprus that lies on the east of the Mediterranean Sea, as historic core and harbor [53].

According to N. Doratli [54], the history of Famagusta is divided into seven particular periods. The first one lies between 648-1192 AD when the eldest settlements were founded. The Lusignan period lasted from 1192 to 1489. During the period, Famagusta’s Eastern Mediterranean area, its harbor and the walls were improved. The time period between the Lusignan period until 1571 was called the Venetian period during which differences in socio-cultural life had a deep influence on the architectural style and design of their environment. During 1571-1878 Famagusta was occupied by Ottoman and the era was named the Ottoman. The city was transferred to a modern city in the British time (1878-1960). Additionally, the sixth period continued between 1960 to 1974 with 1974 being the last one [41,53]. According to TRNC 2006 Population & Dwelling Census, the city consists of 35,453 people. Before the division of the island in 1975, the city was well known as a regional and tourism center. These days, Famagusta houses a variety of residents including EMU university staff and students from different countries, local Turkish Cypriots, and immigrants who have come from the south part in 1974 and from different parts of Turkey.

Figure 6. Map of the Cyprus showing location of Famagusta (Oktay, 2007)


Table 2. Assessment of the Indicators QOL in Famagusta Q

UA

LITY

OF

LIFE

IN F

AM

AG

UST

A

OB

JEC

TIV

E IN

DIC

ATO

R

Environmental or Natural

Characteristics

Positive Point Negative Point

Use of recycle and renewable materials. Suitable conservation of water edge.

Lack of enough conservation about agricultural land, farm land and biodiversity.

Lack of consideration about using the renewable energy. Lack of greenery and plants. Lack of waste management.

Uncomfortable outdoor temperature because of lacking trees and plants.

Increase sound pollution in streets. Inadequate lighting elements in public open spaces.

Physical Characteristics

Different type of Housing. Easy access to the existing facilities.

Mixed use land.

Inappropriate building proportion. Sprawl form creates many problems.

Lack of urban facilities and amenities. Lack of controlling on the density.

Quality of Urban Mobility

Connectivity, and movement in pedestrian networks.

Low quality of pedestrian. Lack of cycling facilities and paths.

Lack of public transportation. Lack of parking spaces

Cultural Characteristics

Holding Spring festivals and live Concert in public open spaces for

different occasion.

Lack of museum, theater and other cultural life to introduce the rich background of the city.

Lack of protection about cultural heritage. Infrastructural

Indicators Adequate hospitals. Adequate clinic and health centers.

Demography The number of population at 2006: 35,453. The number of disable people at 2006: About 4,597.

Economic Characteristics

Affordable housing. Easy access to facilities because of

proximity.

Lack of considering renewable energy causes high energy cost.

Political Characteristics Lack of urban policies or strategies.

Lack of urban fair rights. Lack of responsive urban legislation.

Weak urban management.


Equal access to affordable building. Easy access to all services.

Increasing diversity.

Lack of consideration of some important requirements in residential building creates many problems in streets like lack

of parking spaces. Ignoring the disabled people, and children.

SUB

JEC

TIV

E IN

DIC

ATO

R


Urban vitality. Diversity.

Safe and secure public space. Lack of public awareness.

Place Identity

Protecting of heritage and historical sites.

Indicating the function of a space. Enhancing urban legibility.

Sense of belonging.

Lack of infill development.

Visual Characteristics Lack of management and regular maintenance.

Lack of visual consideration in skyline properties.

Nowadays, it is so clear Fmagusta have faced with immediate or uncontrolled urban development and incompatible land uses. Lost and empty spaces between buildings are the most negative aspect of the unplanned urban development that decreases the visual appropriateness of the city [50-52,55]. Because the city has an important potential effect on social and economic characteristics in North Cyprus, the assessment of quality of life for its inhabitants is the center of concern in urban policies. According to the above mentioned subjective and objective indicators of quality of life, the city has a safe or secure environment, mix land uses for different users, various types of housing, affordability, friendly neighbourhoods, diversity, different shopping facilities and a strong economy. However, unprotected natural and

environmental properties, the sprawl form of the city, ineffective environmental problem solving, and inappropriate building design have increased the negative effect on the environmental and physical characteristics of the city [40,54]. Lack of public transportation, parking spaces, important infrastructure, and inaccessible streets, little sense of historical values, lack of cultural amenities, lack of park and greenery spaces in different neighbourhoods are the other important problems that have deeply affected the QOL in the town. Generally, the majority of the population are dissatisfied with the maintenance of roads, sidewalks, recreational facilities, noise level of streets, traffic volume and availability of public transportation in Famagusta [42,50,56,57]. However, the high level of security and sense of belonging


are the most important indicators that can increase individual well-being, level of satisfaction and QOL in the city. The government and policies should consider the problems of objective indicators to enrich the quality of life. Table 2 illustrates the negative and positive aspects of objective dimensions and subjective indicators which are mentioned in this study.

4. Conclusions Quality of life is a fundamental consideration in urban

planning that can help overcome the problems of cities and enhance the level of human satisfaction. The study categorized the important approaches which can significantly enhance the QOL in the urban environments. The research collected the objective and subjective indicators for different living environments. The objective dimension of the QOL takes nine indicators into consideration to help designers enhance the quality of life for different urban environment inhabitants. Environmental or natural, physical, cultural, economic, political and social characteristics, demography, infrastructural indicators, quality of urban mobility are considered as objective dimensions of QOL in the urban environments. Meanwhile, as previously mentioned, the social characteristics are defined as both, subjective and objective indicators because the built environment and individual behavior can contribute to the concept. The features of the built environment refer to the quantitative indicators of the society but the behavioral characteristics reflect the quality of individuals’ perception of wellbeing. Also, the subjective indicator is defined as the identity of a place and its visual characteristics which have a fundamental influence on the QOL. Famagusta, as one of the most important cities in North Cyprus, is evaluated according to these indicators. As it is mentioned in Table 2, although people are not pleased or satisfied with the maintenance and management of the trails, the safe urban environment and sense of place attachment enhances individual well-being, level of satisfaction, and the quality of life in the city. Furthermore, mixed land uses, familiar or friendly environment, diversity, easy access to different facilities, different types of housing, and cultural aspects of the city help increase the level of satisfaction. However, the following solutions can be utilized to solve the existing problems: Improve sustainable public transportation, parking

spaces, Sustainable street networks with respect to the

individual abilities of all people like disabled people, and, improving street maintenance, and reducing traffic density.

Planting trees or creating green belts to increase comfortable outdoor temperature and decrease sound pollution,

Increase the compaction in urban design development,

Prioritizing and addressing the needs of people e.g. proper recreational facilities, available and accessible parks, shopping facilities, and schools,

These results recommend that the future policies related to residential quarters and buildings should consider required full services e.g. parks, parking spaces, and other necessary services that are easily available and accessible.

Use of strategic planning with long term decision-making and problem-solving that control sprawl form of the city and create healthier living areas.

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DOI: 10.13189/cea.2020.080514

A Quest on the Role of Aesthetics in Enhancing

Functionality of Urban Planning

Hourakhsh Ahmad Nia1,*

, Fashuyi Olugbenga2

1 Department of Architecture, Alanya Hamdullah Emin Pasa University, Alanya, Antalya, Turkey 2 Federal University of Technology Akure Ondo State Nigeria, Nigeria



(a): [1] Hourakhsh Ahmad Nia, Fashuyi Olugbenga , "A Quest on the Role of Aesthetics in Enhancing Functionality of

Urban Planning," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 873 - 879, 2020. DOI:

10.13189/cea.2020.080514.

(b): Hourakhsh Ahmad Nia, Fashuyi Olugbenga (2020). A Quest on the Role of Aesthetics in Enhancing Functionality of

Urban Planning. Civil Engineering and Architecture, 8(5), 873- 879. DOI: 10.13189/cea.2020.080514.


Abstract In view of the dramatic increase in the

population of world cities, the necessities of aesthetic

urban planning have increased. Addressing the aesthetics

problems of urban spaces implies working with new

models of aesthetic cities for developing comprehensive

urban planning. This study highlights the importance of the

consideration of urban aesthetics in the urban planning

process using the qualitative grounded theory study as the

main methodology. The study further showed the need for

planners to consider economic and social outputs in

planning considerations. The study contributes that the

planning process should be tailored to implement aesthetic

inherited planning into urban planning management.

Keywords Urban Aesthetics, Urban Planning,

Qualitative Grounded Theory, Pillars of Urban Aesthetic

Planning

1. Introduction

Current estimates show that more than 50% of the

world’s population resides in urban areas. The population

may also rise to 70% by 2050 [1]. From the aesthetic point

of view, it can be observed that urban planners provide

some of the worst as well as some of the best form of urban

spatial configuration. Indeed, urban aesthetics is a

reflection of poor or wholesome urban planning. On the

one hand, the challenges posed by poor environmental

judgment enhance socioeconomic disparities and stress and

are also related with urban well-being and health. On the

other hand, urban aesthetics itself is a reflection of the

quality of life as well as the socio economic, cultural and

physical aspects of urban design collectively considered.

An umpteenth record of research across disciplines

including urban and aesthetics studies has been

documented on the paths associating urban planning and

aesthetics [2, 3, 4]. The purview of ‘aesthetics’ within the

Town Planning discuss extends no further than the

reference to the external design of a building. And, it has

remained a tradition that many architects would normally

argue that the exercise of aesthetic control on development

proposals should not be the responsibility of planning

bodies and that owing to the subjective nuances involved,

such matters should be the exclusive privilege of architects

and clients alone. According to the Planning policy

guidance (1990) good design which is compatible with

character and scale with its surroundings should be the goal

of clients and professionals involved in the development

process. The guide further asserted that the obligation to

reject poor designs especially those that are conspicuously

out of harmony and scale with their surroundings lies with

the clients, designers and planning authorities. Authorities

should recognize that aesthetic judgments are in

themselves subjective and as a result factor the applicant’s

aesthetic taste in their decision for approving or rejecting

proposals [5].

Thus, it can be stated that the proper use of space at any

time is determined by insightful aesthetic judgment. Such

874 A Quest on the Role of Aesthetics in Enhancing Functionality of Urban Planning

judgment is related to the aesthetic theories which are

fundamental in making sense out of the experiences and

perceptions regarding the daily use of space. Put differently,

aesthetic theories define the paths to aesthetic planning.

Aesthetic planning approach is more successful and

context-oriented when beneficial implements to discuss the

values of urban space are developed especially within

pragmatist and phenomenological philosophy.

Planning theory, the seedbed for aesthetic planning [6],

is usually perceived in the context of the planning process

and that it relates to the theories of planning and objects of

planning. It can be observed that while contemporary

planning leans to the procedural theories of planning,

theories of urban design and architecture have endured

substantially a system of subjective planning. All planned

decisions either reached objectively methodical or

systemically subjective, often have unplanned

consequences. It is stressed that these consequences arose

as a result of loop-holes in the basis upon which the

decisions were reached and formulated [7].

The strength of the planning theory lies in its ability to

reach goal decisions and evaluate alternative options. The

most vivid example of these is in the putting forward of a

set of alternatives and assessing them quantitatively and

scientifically. However, these statistical assessments are

incapable of capturing the subjective desires that underpin

real-life situations.

Besides, strong aesthetic considerations are precluded in

contemporary planning thoughts because of its methodical

stance. From the pragmatist perspective where products

and the processes that led to it demonstrate an ensemble,

aestheticizing of the urban space is tantamount to urban

space development [5]. In addition, the fact that

architecture and urban design remains a vital part of

planning underscores the role of the theory of aesthetics in

urban planning. Hence, the lack of aesthetic view-points

jeopardizes urban planning theories. Therefore, this study

asserts that the aesthetic concern of the urban environment

is of immense significance to urban planning professionals.

A paradigm shift in planning in the 1960s situated it

apart into two formal lines of thoughts which were the view

that planning is a pedagogical approach to reaching goals

and a theory-based system view of planning [7]. The

systems view is usually a statistical approach and typically

anti-aesthetic although the line of “environmental

aesthetics” in view in this study, could on the equilibrium

has a bearing on the systems view of a public urban space.

As such, aesthetics of a public urban space has become

relevant in cities with static urban-imagery, or picturesque

townscapes, as well as with social-life of the people, their

environments, and the processes of urbanism [7].

Thus, highlighting the importance of urban aesthetic

from phenomenological point of view is also germane to

this study. Despite these, aesthetics remains largely

unconsidered in urban environmental planning. Some of

the reasons for this relate to the ambiguity in the definition

of the urban environment itself. This is elucidated in the

contentions that arise in demonstrating the urban

environment as partly objects of art, and admitting that

aesthetics as a term exclusively pertinent to art. On the

other hand, the duality of the designer and urban planner,

as organizer along with enabler and controller seems to

assist enhancing “aesthetics” in urban planning

programmes.

2. Material and Methods

2.1. Urban Aesthetics

It is a point of fact that urban aesthetic is an irreplaceable

tool for promoting city idiosyncrasy identification and

urban dynamics [8]. The assessment of what constitutes

beauty in a city is beyond architectural characters, traffic

controls and the noise effects, building styles, but historical

and social features as well. Along these lines, on one hand,

it has been shown that an increase in the aesthetic qualities

of cities enhances its appreciation while on the other,

studies have shown that “appreciation” in itself is exacting

to conceptualize, nebulous and difficult to justify. The

quest to unravel “what it means to appreciate a city” is one

of the most profound discussions in urban aesthetic design.

Berleant and Carlson [9] asserted that “…the aesthetics of

the city is an aesthetic of engagement”. The duo implied

that the aesthetic of urban settings works by observer’s

active involvement and participation to impact on space.

Urban spaces with delightful aesthetics deliver hedonic

happiness to participants via relaxation, observation and

reflection [10]. In view of this, aesthetic design needs have

become imperative in urban environments. Realizing the

mutuality of engagement between human needs and the

aesthetics of the environment in urban settings, Stamps [11]

made a case for further research on the quality of the

perceived environment.

Figure 1. Aesthetic and the complementary paradigm of sustainability


Tiesdell & Carmona [12] laid further emphasis on the

significance of aesthetics as a dimension of urban design in

the design process. Other factors such as political, social,

economic and legal nature are still required despite

complementing the urban design with aesthetic efforts. It

can therefore be put forward that aesthetic quality in urban

environment is a component of sustainability alongside

social, economic, and ecologic aims, which are other

components of sustainable development. This assumption

precludes our worldview of aesthetics as being related to

external visual quality alone; but that the concept goes

beyond and should be observed through a more

comprehensive framework that factored other dimensions

of urban design (See Figure 1).

The significance of these studies could not be overstated.

For one reason, it is significant for the human

physiologically and psychologically comfort. For the

second, it is needful for solving associated problems linked

to urban aesthetics. This may include such concepts as

ugliness and visual clutter which are notorious for

minimizing environmental hedonism. Thus, aesthetic value

of spaces is associated with user’s assessment of the spaces.

Observers appraise their evaluation of a place positively or

negatively depending on the beauty or ugliness of the place

[13].

There are three main types of urban aesthetic

considerations during the planning process. These are

formal aesthetic, symbolic aesthetic and sensory aesthetic

[14]. Maturity in planning requires experience to seethe

through these factors.

a). Formal Aesthetic: This involves appreciating

structures and shapes in the environment for their own

sake. This aesthetic paradigm views the geometric

quality of the environment as the dominant or

important factor.

b). Symbolic Aesthetic: This is concerned with pleasure

enhancing meanings associated with environmentally

derived patterns. It has to do with feelingly

experienced pleasure as a result of the peculiarities or

specific landscape of the built environment. The built

environment is a symbolic message; acknowledging

this, either consciously or subconsciously is related to

people’s feelings and attitudes towards the

environment and themselves.

c). Sensory Aesthetic: This is a significant aesthetic

especially for relating people’s responses to the

environment. Several authors [15] are of the opinion

that when urban designers and architects emphasize

formal aesthetic, the symbolic meanings of the built

environment become legible. Therefore, it is obvious

that the combination of these considerations is

required to achieve the aesthetically integrated

approach to urban planning.

2.2. Urban Planning

Initially, urban planning emerged as the practical way of

responding to the amorphous environment of the early

nineteenth-century prewar cities but afterwards developed

to an intellectual occupation beyond physical design.

Planner’s primary focus of the initial response was based

on the managerial, political and social aspects of the built

environment and in doing so largely ignored its physical

qualities [16]. The resulting urban declension inflamed

contentious remarks amongst landscape architects,

architects and planners especially after the 1960s.

Ironically, through these contentions, the quest for the

aesthetic quality in public urban spaces gained a further

foothold. It reinforces the fact beyond physical

consideration it focuses on the social and psychological

constructs of the design process. Though “urban planning”

acknowledged the significance of “urban design,”

continuing discussion among urban design and planning

has been viewed in two broad areas: scale and emphasis on

design.

By the late 1850s, city beautification movement under

the leadership of Ebenezer Howard, Frederick Law

Olmsted and Daniel Burnham was initiated as recourse to

the inhospitable and unpleasant American cities. These

architects felt that aesthetic transformation for pleasant

environments has become imperative in cities [17]. The

significance of this operation lies in the maxim that an

orderly environment begets a good society. While

mismatched and unwholesome cities result in crime and

vandalism, good and beautiful environments can enhance

the social life and aspects of proper moral behaviors. In

1890s Camillo Sitte [9], reechoed the strong impacts of the

physical environments on the human soul. He went further

to say that the city should be a happy and secure habitat for

dwellers. Thus, the city by purpose should go beyond the

mere functionality of activity areas to the legibility of

artistic pattern. This is imperative to the city planning

profession. The 1950s to 1960s was an era of a paradigm

shift when against the theory of physical determinism.

Theoreticians began to argue in favor of the importance of

the aesthetic of the built environment on the social life of

the people. They emphasized the need for planners to

realize the extent that social forces influence the aesthetics

of the built environment since the goal of urban planning is

to design and maintain a salubrious environment based on

aesthetics and good design. Indeed, a significant amount of

extant master plans suggest the totalitarian and utopian

characters of physical determinism’s approach to urban

planning, in which case architecture and planning became

instruments to destroy disorder and chaotic urban spaces.

Overall, critical examination of planning is expedient in

rethinking the praxis of the profession especially in terms

of aesthetics and quality of the environment.


Figure 2. Urban planner and the required knowledge of Space Organization

Regarding roles and responsibilities, planners have more

to do in the anesthetization of urban spaces than urban

designers and this fact denotes the significance of urban

planning in the aesthetics of future cities. Thus,

contributions and suggestions of planners on the effects of

space organization on the aesthetic value of the city

become very imperative. The process of aesthetic

development of urban spaces is the link between the

higher-level decisions to the levels below; such as from

regional to town planning. Hence, planners should have a

comprehensive overview of the fundamentals of aesthetic

planning and the main stages of the city planning process

that lead to the aesthetics of the urban design.

There are two main approaches to urban planning:

The classical approach “the blueprint view of

planning”: The approach which emerged in architecture

was developed as a response to city aesthetics while

considering public health. Usually, the planner is a

visionary who conceives a futuristic model for a specific

area. He is a virtuoso employing his acumen on the society

to manipulate spaces in an attempt to provide hedonic

environments regardless of the society related to the place.

This approach to planning rest on the philosophical

realization that man is the measure of all things and can

provide solutions to his problems [18].

Figure 3. The planning processes

The systematic view of planning: This approach to

planning can be succinctly stated as 'survey - analysis -

plan'. The pioneer was Sir Patrick Geddes (1854-1932)

who is attributed to have developed the principles of

modern town planning. The tenets of his approach are the

use of scientific methods as evaluative options, the

assertion of comprehensiveness and the application of

“instrumental rationality”. Thus, the systematic view

approach is out-modestly pedantic for which it is denoted

“the rational approach” [19]. Figure 3 is a figurative

narrative of the systematic approach to planning which has

been adapted in umpteenth varieties in many countries

(Figure 3).

2.2.1. Approaches to Aesthetic Urban Planning

The aesthetic concept is not new in urban design and

planning. Traditional theories of urban design focus on the

physicality of the built environment alone. With this

realization, planners figure out other theories to fit

planning into realms beyond mere physicality.

"Figure-Ground" theory, for instance, underscores the

usefulness of the open space and interconnectedness of

solids and voids in the urban space, whilst the undergirding

of the "Linkage Theory" relates to urban thoroughfares and

the streets. The "Place Theory", puts emphasis on the

relationships between the social aspects of the space and

human activities [20,21,12]. In all of these approaches,

explicit visions on urban sustainability were hardly

demonstrated. Hence, more recent approaches, amongst

which are Green Urbanism and New Urbanism, have

elaborated on the impacts of social aspects of planning on

the built environment. In practice, these planning

distinctions do not exist. Despite all of these, a set of

liveability and sustainability interventions (rather than

branding reality) amenable to local nuances are more

copious in cities. In each city, constraints and opportunities

should be wholly addressed to reflect peculiar urban

systems of environmental, social and economic life [22]. It

has been observed that the system of transportation impacts

the liveability of contemporary cities in real-life situations

[23] and that social integration [24] and resource

management enhances resilience and durability in cities

[25]. In point of fact, the interactions between dwellers,

infrastructure and transport networks are the undergirding

of the micro-structure of sustainable cities [26]. In this way,

aesthetic cities should integrate environmental, social and

economic components into a systemic whole. Balancing

the components requires an integrated decision-making

process aimed at achieving urban design objectives.

It is also useful to reecho that Urban Planning is the

foundational undergirding for all proposed urban

development including housing. It considers the complex

interplay between social (social amenities), institutional

(capacity and policies/regulations) cultural (locally

acceptable), environmental (resilient locations and healthy

water/sanitation), financial (public and private resources),

economic (close contiguity to informal/ formal


employment chances), and physical components

(infrastructure and land) in arriving at urban design

solutions. Indeed, urban planning is a multi-sided process

that requires consolidated preparations to achieve a balance

between politics, spatial planning objectives and

stakeholder’s actual needs. Thus, an iterative process

requiring a full range of stakeholders involved in

decision-making and incorporating feedback often results

in a promising urban design approach. Figure 5 illustrates

the complexity of issues and sectors considered.

Figure 4. Three main pillars in aesthetic consideration in urban

planning

Figure 5. Sectors to be considered in Urban Planning process

2.2.2. Collaborative Planning as Proposed Method of

Aesthetic Design

The theoretical discussion on planning, the objectives

and aims reinforces the values already attributed to it. The

realization of this discussion on planning has led to the

existing “communicative turn” in planning theory [27].

“Communicative Planning Theory” is basically a theory of

the praxis of the planning; interpreting and describing the

planning profession. Khalee [28] observed that the theory

goes further to point attention to what moral issues are

involved in the profession. The seedbed that anchors the

theory has been said to draw from Jiirgen Habermas’s

theory of communicative action although the extent of this

is left for speculation [27, 29, 30]. Habermas, being a

philosopher posits that rationality cannot solitary bring up

“instrumental rationality’ and that as a result, a rational

debate of “values” is conceivable. Aestheticians have

abstracted from Habermas's theory to demystify the role of

aesthetics even though aesthetics is not the main anxiety in

his theory. Despite of this, Habermas emphasized that

aesthetic and art experiences exert a significant influence

on modern society to enrich life-worlds. Habermas's

aesthetics may offer the needed conceptual support for

planning particularly the awareness of novel perspectives

which may help enriching planning applications.

3. Discussions

3.1. Modeling on Aesthetics in Urban Planning

This involves the operationalization of aesthetic

planning concepts for planning and it has been categorized

into two according to its use. The uses are first, for the

purpose of urban planning and second, for the utilization of

planning program for aesthetic design of the urban space.

Urban planners need to consider aesthetics as the main

environmental policies which require implementation in

planning policies. In this regard, formal, symbolic and

social considerations of aesthetic design need to be put

together in such a way as to implement the principles of

aesthetic design in the planning process. This view is

consistent with earlier positions of this study that aside

from environmental aspects of urban aesthetics, planners

should reflect on the economic and social outputs of their

planning considerations. Overall, it can be stated that the

planning process should be utilized in such a way that

aesthetic inherited planning can be impacted by urban

planning management. The following model (Figure 6)

represents the strategical thinking model for urban

designers who need consideration during the urban

planning process.


Figure 6. Strategical thinking model for urban Planners

4. Conclusions

Urban population explosion and the attendant increase in

social and psychological problems reinforce the need for

urban aesthetic planning by urban planners. The view that

urban planning is a decision-making process independent

of cities’ subjective perception calls for alternatives. The

alternative should be reinforced with pragmatist and

phenomenological ideas to strengthen the aesthetic quality

of urban space and to promote the urban planning process.

The study revealed that the homogeneity of produced

aesthetic in urban planning, broadly speaking, is

non-confrontational and acceptable. The study also serves

as a caveat for planning theorist to recognize the effects of

monolithic cities on suitability. Hence, it is imperative for

them to be engaged with image creation to foster creative

planning. Realizing that images are innately political and

are imbued with knowledge and power, implication and

force makes this especially so. These notwithstanding,

aesthetics concern goes beyond the purview of the built

environment to the social and cultural construct and as a

result, urban diversity can as well be examined as a cultural

and social variety. Therefore, the urban space

configuration should be a plan to accommodate social,

environmental, and cultural nuances. Overall, comparing

the traditional model of urban planning which indeed

focuses mostly on the abilities of the urban designer to

employ different knowledge from different disciplines for

providing urban design solutions, it remained obvious that

city planning leading to urban planning is an

interconnected process. Doubtless, city planners need to

have this knowledge - in architecture, landscape

architecture and urban design -as well as in other fields so

as to achieve increasing aesthetic value of prospective city

planning. It has also been stated in this study that there are

three main components to urban aesthetic considerations.

From this perspective, this study highlights the need for

economic and social considerations aside from aesthetics

outputs in planning designs. Overall, it can be stated that

the planning process should be utilized in such a way that

urban planning management can influence aesthetic

inherited planning to reach desired goals and objectives.

Research on the methods for implementing aesthetic

planning processes has remained largely unattended to and

its therefore suggested for further studies.

Acknowledgements

This research did not receive any specific grant from

funding agencies in the public, commercial, or

not-for-profit sectors.


The authors declare no conflict of interest.

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[30] Naouel Hanane Boudjabi , Foued Bouzahzah , Abdelouhab Bouchareb (2018). Urban Strategies for a Renewal of Algerian Cities: Constantine of Tomorrow. Civil Engineering and Architecture, 6(1), 18 - 24. DOI: 10.13189/cea.2018.060102.


DOI: 10.13189/cea.2020.080515

Borders (in between): A City within a City Decoding

Different Morphologies of Fragmented Housing

Hatice Kalfaoglu Hatipoglu, Seher Beyza Mahmut*

Faculty of Architecture, Ankara Yildirim Beyazit University, Ankara, 06110, Turkey



(a): [1] Hatice Kalfaoglu Hatipoglu, Seher Beyza Mahmut , "Borders (in between): A City within a City Decoding

Different Morphologies of Fragmented Housing," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 880 - 889, 2020.

DOI: 10.13189/cea.2020.080515.

(b): Hatice Kalfaoglu Hatipoglu, Seher Beyza Mahmut (2020). Borders (in between): A City within a City Decoding

Different Morphologies of Fragmented Housing. Civil Engineering and Architecture, 8(5), 880 - 889. DOI:

10.13189/cea.2020.080515.


Abstract Cities act as living organisms that bring

people together and contain different social aspects in

heterogeneity. When people with similar lifestyles

regarding income and culture come together in enclosed

groups, places are divided into physical and social gated

communities which create unseen borders between

different groups of people. The aim of this study is to

demonstrate the effects of segregated spaces separated by

physical or social borders in the city. Firstly, gated

communities, which are presented as contemporary walled

island, will be discussed by focusing on the concept of

segregation as a result of these borders in relation with

morphology. Accordingly, an evaluation framework has

been developed on three main scales, which are based on

the Conzen’s classification of space, to create a systematic

overview to analyze the segregated morphology. Sinpaş

Ege Valley Housing Project and its surrounded slums,

which were located on the Dikmen Valley of Ankara

having a different typology and borders in-between, is

chosen as a representative case of the aforementioned

segregation to analyze the effects of these unseen borders

on space typologies, people’s space usage and activity

patterns.

Keywords Segregation, Neighborhoods, Housing

Quality, Gated Communities, Urban Space, Urban

Morphology

1. Introduction

The city, which integrates people through the

development of social interactions in everyday life, is a

social entity [1]. Habitat selection and choice of particular

environmental quality cause a clustering in city so that the

city becomes a set of areas of different groups which tend

to define themselves in terms of "us" and "them" [2]. A

clustering process tends to occur in cities based on

perceived homogeneity, differing interpretations of

environmental quality, lifestyles, symbol systems and

defenses against overload and stress. Although the

homogeneity which appears because of the tendency of

similar people in an area is arguable for urban life, settling

in this way occurs inevitably [2].

Today, people’s social, cultural and economic relations

define their consumption habits define their consumption

characteristics. The space is also defined as a consumption

object which provides a place to the individual. For this

reason, economic restructuring triggers changes in the

global city’s structure [3]. As a consequence, while the city

is being spatially fragmented; the society is also

fragmented by socio-economic and cultural divisions.

These two processes of fragmentation in space and social

structure are mutually interdependent. As a result of these

processes, the city becomes a segregated organism and is

divided by social groups that cause conflict.

Urban morphology is the study of the shape and form of

settlements. Morphological structure describes urban

elements as physical features of cities and their hierarchy


on different scales, from architectural elements in a room,

dwelling, building storey or building, to urban elements

such as façades, buildings, streets, routes, neighborhoods

and urban regions [4]. Every single detail of the city

influences morphology of spaces. According to different

segregated parts in city, morphologic pattern inherently

changes.

This study aims to analyze the morphological

components of urban segregation in different typologies to

highlight the fragmentation of urban space through

different kind of social entities as a result of physical/social

borders. In order to demonstrate the spatial and social

effects of this fragmented parts of the city, segregation is

discussed in relation with morphology.

2. The Scope of the Study and Conceptual Framework

2.1. Fragmented Parts of Cities

Segregation is the separation of one group forum another

which occurs in both formal and informal way. This

division depends on indicators of difference, where gender,

race, ethnicity, religion or social class, is used as the

foundation for confirming a dissimilarity between groups

and populations [5]. Although non-geographical platforms

are the scenes of the articulation between social groups, [6],

urban segregation is saliently spatial.

People who have the same social backgrounds with

similar characteristics show a tendency to be a group in

themselves and define their own community/territory.

However, this situation becomes visible due to

intensification of social differences over time which causes

a social segregation. Andersen defines social segregation

as follows: “Social segregation is the spatial segregation of

ethnically or socially different groups, leading to increased

social and cultural differences between groups” [7]. There

must hence be some cultural homogeneity and execution of

unwritten rules, symbols and behavior [2].

Social and spatial segregation are often discussed

together. Social segregation causes people to cluster in

certain places of the city which causes spatial segregation.

Thus, areas that can be defined as enclave have been

created within the city, which is a small, distinct area or

district where an insular group of people live [8]. Besides,

the urban enclave is a way to shape places in cities where

like-minded people can find each other and be part of the

greater whole [9]. Race, income, class, ethnicity are parts

of the categories of it [10]. These categories can be

grouped under certain headings. For instance, according to

Marcus, enclave grouping can be classified as

outcast/classic ghetto, immigrant and cultural enclaves and

citadel [11]. Outcast ghetto is a community of socially

excluded people. Immigrants and cultural enclaves are

areas of the same ethnic origin, similar lifestyles and

mindset. The Citadel is the closed communities formed by

the upper income group's spatial separation and

self-isolation. In all these cases the key process is habitat

selection based on values and environmental preferences.

Consequently, group identity is reinforced by clustering,

manifested by environmental symbols and enclosed by

boundaries [2].

There are many reasons behind these disintegrations,

which occur voluntarily or compulsorily [12] in the city

and become physically observable. The reason for spatial

differentiation is due to the desire of people to live with the

people they see equivalent. In general, segregation of the

upper classes is based on voluntarism, while the lower

classes are due to necessity.

The enclaves formed by the upper income group are also

called the gated community. Gated communities, provide

security and exclusivity to its residents through a

combination of physical barriers, surveillance, security

guidance, and community self-regulation of architecture

and behavior [13]. In literature, the main reasons for

moving to a gated community are referred as the fear of

crime, violence in urban environment, the expectancy to

get better habits and lifestyle, the escape from the city

problems which are caused by low-income people asking

for money [1]. Besides, the increasing income inequality

between the upper and lower sections of the society is a

factor supporting the formation of the gated community.

There are different perspectives that discuss whether

spatial segregation has positive or negative effects on city.

For former, people welcome the similar groups living

together because they are easier to mingle with,

togetherness makes people feel more belonging to the

place and create reliable spaces by establishing a social

network. The process of clustering helps cultures survive

and provides appropriate organizations of meaning and

communication. Likewise, inhabitants share symbols and

apply unwritten rules which were shaped by their

behaviors [1]. As a result of having fixed and defined areas,

the problems and the level of stress are minimized. As well,

homogeneity seems to increase neighboring more than

heterogeneity [2]. According to the latter approach, social

segregation that brings spatial segregation in the city is

opposite to the nature and heterogeneity of the city.

Keeping people with similar backgrounds and cultures in

borders will create segregated communities which will not

be able to provide an integration of a community which we

need [1]. Fewer job opportunities, intense discrimination,

scarcity of public services and infrastructure are the

examples of various limitations which are imposed to

certain population groups. With the guidance of several

studies, disadvantaged urban populations would benefit

from a more non-segregated distribution of people in urban

spaces [6]. The preference of new living spaces by groups

which are gradually separated and differentiating from

each other plays a role in the transformation and alienation

which reduces sense of belonging of people in cities [14].

882 Borders (in between): A City within a City Decoding Different Morphologies of Fragmented Housing

2.2. Morphology of Segregation

The city is defined by and structured through the

heterogeneity of the differences[15]. According to

Lefebvre [16], the form is produced by the diversity.

Besides, Brotchie et al. [17], describes the urban form as

the pattern of residential and non-residential activities in

urban and their reflections on which accommodates them.

These discussions are in the scope of the researches in

urban geography and interurban/intraurban relations which

study spatial aspects of urban development. In inter-urban

relations, urban areas are studied in terms of their

morphology, which is the study of the form and shape of

settlements [18]. Clark describes urban morphology as the

study of the form in systematic way, plan, shape, structure

and functions of the built fabric of cities/towns and of the

origin and the way in which this fabric has changed over

time [17]. In this systematic approach, the elements of the

urban morphology have been described as plots, buildings,

use, streets, plans and townscapes [19].

Studies on morphology have been carried out with

different perspectives. For long years, effective methods of

explaining and exploring the physical form/shape of urban

spaces, have been developed by urban morphologists. [20].

M.R.G. Conzen was one of the important names that

guided morphological research. In some of the current

studies today, the systematic established by his researches

has still been used. Conzen [21] asserts a tripartite division

of urban form into first, the town/ground plan; secondly,

building; and thirdly, land and building utilization, which

is the intersection of both [22]. Morphological regions are

shaped and differentiated according to these divisions.

When looking at the city or the neighborhood from top

view, the differences seen in morphology which point to

close and homogeneous islets that occur within the

heterogeneity of the city. It shows that residents in one

place have different relationships and systems than others.

Opportunities and limits in these environments affect the

satisfaction and behavior of people; therefore, it directly

influences the general health, happiness and welfare of the

individual/neighborhood and society [23]. As a

consequence, a cluster of distinct segregation emerges at

every scale.

3. Materials & Methods

It has been developed a framework to evaluate the

effects on different morphology. This evaluation, which

aims to create a systematic approach to assessing these

components, is based on literature review and Conzen and

Gehl’s concepts. Table 1 shows the evaluation criteria of

different morphologies. Conzen’s classification of scales

underlies the indicators. These scales are further

developed by means of sub indicators in each layer in

order to understand/analyze the codes of morphology

which create segregation in different scales and in more

details. Table 1 shows the evaluation criteria of different

morphologies.

Sinpaş Ege Valley Housing Project and its surrounded

slums, which were located on the Dikmen Valley of

Ankara having a different typology and borders

in-between, is chosen as a demonstrative case study for

the evaluation. The evaluation has been conducted by

using observations on the field and morphological

analyses according to the defined indicators of the

evaluation.

Table 1. Definition Criteria of Different Morphologies


3.1. Case Study: Sinpaş Ege Valley Housing and Its

Surrounding Slums

Sinpaş Ege Valley Housing Project (SEVHP) has been

studied as an example of gated communities and the

morphological differences between SEVHP and

surrounding slums has been analyzed.

The project area (Figure-1) is located on the southeast

of Dikmen Valley in the region known as Yukarı Dikmen

Neighborhood in Çankaya district of Ankara. Urban

transformation projects have been completed in stages in

the northern parts of the valley. However, there are

several advertisements from different construction

companies in the region and it is estimated that projects

such as SEVHP will be shaping the general design of the

district by demolishing the slums in the near future.

SEVHP is a housing project that attracts attention with

889 flats and 49-storey tower and 5 other closed blocks

consisting of different floor numbers. The project

annunciations started at 2016, and today it has almost

been done. It offers different activity areas/facilities and

housing types to privileged people. The most important

feature of the project which is emphasized is to enable

coast life in Ankara. However, there are security guards at

the entrance and the area is monitored by cameras during

24 hours of each day in a week. Moreover, it fits to the

definition of walled island because it is surrounded by

walls at the same time.

There are approximately 85 slums around SEVHP and

they are located/designed in the land in accordance with

the topography. Most of them are in damaged condition.

Although there are no walls at the entrance of the area,

there is a perceptual wall as a symbolic barrier built by the

inhabitants of these slums against foreigners coming from

outside. Additionally, these slums have created a dynamic

structure in itself.

Figure 1. A view from the field

4. The Evaluation Framework of Different Morphologies

Analysis of the morphological components of urban

segregation has been categorized into three basic elements

of the city plan following the Conzen classification:

streets, parcels and buildings [21]. Each of these elements

is interrelated each other. His concept of the composite

city plan defines variations in forms, uses and

configurations found in different parts of the city. This

plan consists of different units called unit plans and these

are best observed in street, parcel, building size and forms

[24]. Unit plans also contribute to the stratification of the

urban landscape [25].

4.1. Street Scale

According to Conzen [21], street represents open spaces

covered by street lines and reserved for the transition of

pedestrian and vehicle traffic. The composition of these

adjoining and interdependent spaces within an urban area,

have been constituted the street system. The street system

is one of the irrevocable parts of urban design. Efficient

and distinctive use of urban areas can be created as a

result of plausible and well-considered street plans.

4.1.1. Permeability and Accessibility

Street pattern contributes to creating permeable spaces.

Permeability is a crucial urban design element for

perception of spaces. It provides movement and

accessibility opportunities in an area. According to Carr,

there are three different accesses which influence the

permeability of a place [26].

Visual Accessibility (Visibility): People can see into a

space before they enter it.

Symbolic Accessibility (Symbols): Cues (symbols)

can be animate or inanimate (someone’s entrance to

space is threatening or not, a feeling).

Physical Accessibility: Space is physically available

to the public.

4.1.2. Open/ Public Spaces

Public spaces are irrevocable part of urban system for

citizens. While Wilson [27] introduces his hypothesis

which focuses on an instinctual connection between the

human self and other living organisms, he has claimed that

urban public spaces offer clear health benefits for citizens

by getting fresh air and exercising. Also, humans seem to

need both social contacts with others and some access to

greenery in order to maintain psychological balance to be

provided by good public spaces [28].

When the public spaces of both territories are analyzed,

it is observed that there are 5 main open spaces in the

vicinity of the district but none of them are inside the slum

settlements. In other words, these open spaces mostly serve

to the housing blocks around. However, there are


quasi-public spaces inside SEVHP, which are preferred

more than the surrounding public spaces by the inhabitants

of the gated community.

Urban designers influence the patterns of human activity

and daily/social life by shaping the built environment.

Similarly, environmental opportunities obviously affect

what people can and cannot do [26]. Jan Gehl has

categorized the outdoor activities in public areas under

three headings; necessary activities, optional activities, and

social activities [29].

Necessary Activities: These are imperative activities

and occur whatever physical conditions are, like

going to school, waiting for a bus.

Optional Activities: most of the recreational activities

that are especially pleasant to pursue outdoors are

found precisely in this category of activities. So, it is

vital in connection with physical planning. Like

walking to get some fresh air, it can be achieved if

time and space make it possible.

Social Activities: This type is based on the existence

of others in public spaces. In this context, only those

activities that occur in publicly accessible areas are

examined like children at play, greetings and

conversations etc.

Consequently, Gehl supports that when outdoor areas

are of poor quality, only strictly necessary activities can be

occurred [29].

4.2. Plot Scale

The areas which are unoccupied by streets or in part of

street blocks can be defined as a plot [21]. Each block

contains one or more land parcels and each of them is a

land use unit. It is above the ground and defined by

boundaries physically.

4.2.1. Parcel

Conzen has contributed “burgage cycle” term to

literature. The cycle implies changes in the number of

buildings in one parcel. The initial structure within the

parcel is the addition of new buildings in parallel with the

increase in construction activities in the city over time,

and the number of these structures, such as economic

breakdowns, natural disasters, new zoning rules and wars,

has decreased for several reasons. These changes on the

parcel and its structures directly affect the formal structure

of the city [24].

4.2.2. Density

Changes on the basis of the parcel also have an

influence on the density of the area. According to Edward

Ng [30], building density has a complex relationship with

urban morphology; it is vital in the shaping of urban form.

Creating dense areas produces positive outcomes

according to some researchers, while others claimed that it

caused a social collapse [30-31]. For instance, increasing

urban population leads to a scarcity of land and it is an

example of the spatial benefit of multi-storey buildings.

However, according to Skjaeveland&Garling expanded

density leads to an increased sense of loneliness and a

decreased sense of belonging to a neighborhood [31].

4.3. Building-Block Scale

The block-plan of a building is the area occupied by a

building and defined on the ground by the lines of its

containing walls [21]. It is an essential element of the

town plan, loosely referred to as the 'building'.

Consequently, interventions on building level, has been

also accepted as a morphological element.

4.3.1. Hierarchy of Spaces

According to Edward Ng [30], to learn how people feel

about living in high density cities, ratio of people per unit

area does not respond to the answer. It is more crucial that

the functions in these places and how these are designed

in the whole space. In particular, the notion of private,

public and semi-public space plays a central role here as

Newman has emphasized [32,33].

4.3.2. Inner Scale Interaction

There has been substantial interest and study over the

years into the relationship between human behavior and

urban form [2,28,30]. According to Dear&Wolch, social

relations can be constituted through space, constrained by

space and mediated by space [34]. Therefore, every

physical feature on space has an influence for changing

human behavior.

According to Gehl physical arrangement can prevent or

promote visual and auditory contact in at least five

different ways: walls, distance, speed, level and

orientation [29]. If there are no walls between people,

people can communicate in small distance, speed in

settlement is based on walking rather than driving and

houses in the same level and their orientation look each

other; The contact between individuals have been

promoted.

5. Results of the Evaluation of Different Morphologies

5.1. Street Scale

In SEVHP, there is a square in the middle of the project

area which is enclosed by blocks around it. Inside the

walls of the project, it is impossible to perceive this

structure as real street system. However, SEVHP as one of

the attached walled islands to the streets of the slums

which have been shaped organically in harmony with the

topography.

When SEVHP and its surroundings are analyzed in


street scale, SEVHP is in a position that affects

permeability in a negative way. Since it has a closed edge

of approximately 150 m, which prevents the perception of

the Valley and what is happening in the north and

disconnects visual interaction. Physical access is also not

possible, since the people from outside are not allowed

entering the area and entrance is under the control of

security personnel and cameras. Likewise, since the area

addresses only one group, symbolic accessibility is not

possible at this point.

Slums contain more open entries than SEVHP. The

streets are shaped to the extent allowed by the topography.

No security guidance is required to enter this area. The

general housing pattern structure is not formed by big

blocks; they are separated from each other and take up

small space in the land. In this case, while physical and

visual accessibility is provided there is a break in the

symbolic accessibility only for those who are strangers.

Table-2 shows the types of accessibility analyzed in both

habitats.

Table 2. Types of accessibility provided by habitats (Created by the authors according to Gehl [29] )

3 types of accessibility

Visual Physical Symbolic

Units SEVHP × × ×

Slums √ √ ×

When the opportunities presented in the case study are

examined, it is observed that both groups can bring

necessary activities as compulsory, and optional activities

occur though under different conditions and at different

levels. In SEVHP, attention was paid to the diversity of

places where people will come together. However, these

places act as private 'club' areas which require membership

instead of being a public or 'quasi-public' place. [26].

Slums settlements can only reach parks around

neighborhood which are not specific for them. It is obvious

that they contain big differences with the SEVHP next to

them. In this case, it is possible to say that the social

activities that are allowed in SEVHP are higher than those

in slums but activities in SEVHP cannot belong to urban

life because they have located beyond the walls and serve

only their inhabitants with some payment. This situation

promotes fragmentation Table 3 shows the activities which

are provided by each habitat.

Table 3. Activities Provided by Environment

SEVHP Slums

Winter Gardens Recreation Area

Shopping Mall Playground

Hobby Atelier

Playground

Sport Area

Beach

Poll

5.2. Plot Scale

In the phase from 2013 to 2019 (Figure 2-3), there have

been new construction attempts and new zoning plans on

the case study site. The current zoning plans promote

privatized land-uses/housing like SEVHP which results in

the disappearance of small parcels. Cadastral parcel’s

borders have totally changed. Even if there is an

investigation into parcels’ shape only, morphological

changes can be estimated. Additionally, when

figure-ground relations are analyzed, it is obvious that

there is a decimation of slums on the site. Slums in

SEVHP area are demolished and the new building type

has been constructed. When ownership situation and

emptiness/abandonment of the area is considered, it is not

difficult to assume that there will be new construction

projects like SEVHP which totally excludes the

heterogeneity of city, not surprisingly.

Figure 2. Cadastral parcels and figure ground relations at 2013

Figure 3. Cadastral Parcels and figure ground relations at 2019


In the case study, it is obvious that the density of two

areas is totally different from each other. Table-4 shows

the calculations of density for each area. Slum settlements

cover approximately 19 ha of land, while SEVHP covers

only 2,6 ha. Moreover, in slum area there is less living

unit per meter square than in SEVHP. As expected, in

SEVHP plot, there are almost 73 times more people per

square meter than slum area. That demonstrates the

density differentiation between two different housing

types. It is observed that intense units and people on the

SEVHP are totally pressed on the blocks, which are not

convenient and suitable for the nature of human and

nature of neighborhood. On the other side, less dense slum

settlements provide a proper human-scale, better

interaction of individuals and a more perceivable

neighborhood.

Table 4. Calculation of units per square meter & population per square meter

(units/m2) (people/ m2)

85/ 190000 m2

0,0004

340/190000 m2

0,0018

889/26900 m2

0,033

3556/26900 m2

0,132

5.3. Building-Block Scale

In the area, it is noticeable that there are different types

of housing which present different hierarchy of spaces.

Table-5 presents the space hierarchy of each type. In

slums the lack of semi-private space can be observed. For

inhabitants of slums, space hierarchy doesn’t respond to

the basic needs. People live there to fulfill their shelter

needs and there is no consideration of other items like

hierarchical space. Although most of slums have not any

physical arrangement to promote this hierarchy, there is a

sense of space hierarchy perceived when strangers enter

the space and this sense develop organically without

physical borders. Contrary, SEVHP area is well-designed

to provide better conditions for its settlers. All hierarchical

level was applied, also because of its gated functions; area

automatically gives a chance as semi-private usage for its

inhabitants. In Slums this hierarchy is provided in an

organic way, but in SEHVP the aim was to create a

hierarchy against the non-inhabitants. However, according

to Newman because of the height and density of such

housing types, the designed semi-private zones have had

the characteristic of a public zone and even the circulation

routes inside the housing have been used as streets

because of the intensity of the human use [32].

Table 5. Hierarchy of Spaces

Slums

SEVHP

In the case, SEVHP can provide only 1 of 5 elements

which promote a contact, while slum settlements provide

all of these 5 elements. So, even SEVHP claims to ensure

a larger, more secure and luxury environment, it is

deficient in providing small scale physical arrangement

which is important for human contacts and relations in

each other. Table-6 compares these elements between

both habitats.

Additionally, Gehl claimed that just the first few floors

of a multi-story building can provide a meaningful

relation within the ground level [29]. Moreover the people

above the fifth floor are not a part of the scene and cannot

endure a real communication with the ground level events.

Consequently, SEVHP with 49 storeys also cannot

provide a meaningful contact/relation both with the

ground level and the slum settlements. On the other hand,

slums with their human-scaled and low-storey structure in

the pressure and shadow of SEVHP can ensure a

meaningful relationship with their environment. Moreover,

being as a part of the street scene, these housing

contributes to observing and controlling the incidents on

the street, even the strangers; without the need of guidance

and high borders.


Table 6. Inner Scale Social Interaction in Buildings(Created by the authors according to Gehl, [29] )

SEVHP Slums

Walls

Distance

Speed

Level

Orientation

6. Discussion & Conclusions

The most important feature which provides character

and peculiarity to cities is their heterogeneous structure.

However, this heterogeneity has been dissolved with the

changes on socio-economic structures of city and turned

into more homogeneous parts which include “like-minded”

inhabitants. Each of these homogenous enclaves has their

own morphology. Their gates form a dramatic and highly

visible manifestation of social fragmentation and

polarization [26]. Consequently fragmented parts have

very different socio-spatial structures which result in

decreasing sense of place of people, although they have

been located in close proximity.

As a result of the study, it is observed that each habitat

has their own urban life perspective and all of them are

reflected to the space scene. This reflection has been

analyzed on the classification of a tripartite scale.

At street scale, both habitats control the

permeability/accessibility with different elements. While

SEVHP has enclosed with walls as physical borders

which prevent permeability/accessibility of spaces, slum

settlements provide this control without their physical

borders in a symbolic way. However slum settlements still

achieve to be a part of the street and its control is a natural

result of being a neighborhood. Additionally, public

spaces which are provided by both territory present

different characteristics. SEVHP has several activity

spaces inside the borders. Contrary, slum settlement has

not public spaces which are designed specifically only for

its inhabitants. This unequal distribution of activity areas

affects their activity patterns. However it has been

observed that the slum inhabitants create and define their

own activity spaces organically in a more efficient way.

At plot scale, it is obvious that there are immense

transforms when changes on parcel shapes and building

numbers in years are investigated. Parcels with private

ownership have changed through zoning laws and more

than half of the slums have been cleaned from the site. As

a consequent, the area becomes more preferable for

housing projects such as SEVHP. In addition, there is a

huge difference between density of SEVHP and slums.

While dense plot of SEVHP affects the neighborhood

relations negatively and out of human-scale, slums have

more spacious areas and perceivable neighborhood

relations because high density of settlements made it

inconceivable for the inhabitants of a place to recognize

each other.

At building scale, hierarchy of spaces changes due to

the perception of the designers of both habitats. Slums

settlements generally have not semi-private level of

hierarchy because inhabitants want to settle somewhere

only, to provide hierarchy is not meaningful for them but

when strangers enter the area, feel a hierarchy which has

formed organically even it has not walls. However

SEVHP’s spaces are well-designed and constituted by

physical arrangements to accommodate more private life

for its inhabitants.

Additionally, inner scale elements such as the height of

buildings or orientation of living units can provide a

visual or author contact which promotes meaningful

relations with inhabitants. Although the design of SEVHP

has not allowed to contact between inhabitants, slums

include more human-scale interaction elements which

have been formed without design concerns.

As a result, it is clear that SEVHP as a representative

case of gated communities has literally been enclosed with

social/physical walls and designed to promote privileged

life for their inhabitants, ignoring the physical and social

effect it has left to the outside of these borders. The people

around are undesirable for these communities. On the

other hand, slums don’t have physical borders with

defined walls but have unintentional symbolic social walls

to the others from outside. Their spatial effects on

morphology have also been observed in several scales.

Two different morphologies in the same neighborhood

act like the opposite poles of a magnet. Inhabitants of both

habitats perceive each other as a danger in a close

proximity. It seems that there will be new gated


communities, and the demolishing of slums will raise in

accelerations which results in the increase of the tension

between two groups. Additionally, neighborhood relations

will decrease within these mini-cities as a consequence of

this spatial fragmentation.

Here the question raises should new city designs

continue to provide walled islands or it should integrate

neighborhoods? These subjects will continue to be

discussed inevitably. The need is to lead these

transformations in a way that creates a city for everyone

instead of a specific group. In the case that it cannot be

achieved, social segregation will continue parallel to the

spatial segregation. The aim should be designing city that

everyone can live together despite their different lifestyles

and backgrounds without borders.

Acknowledgements



non-for-profit sectors.

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The Impact of Transparency Ratio on Thermal Comfort: A Field Study on Educational Building

Fatma Zoroğlu Çağlar1,*, Gülay Zorer Gedik1, Hüseyin Gökdemir2

1Faculty of Architecture, Yıldız Technical University, Istanbul, Turkey 2 R&D Center, Çuhadaroğlu Metal San. Paz. A.Ş, Istanbul, Turkey


Cite This Paper in the following Citation Styles (a): [1] Fatma Zoroğlu Çağlar, Gülay Zorer Gedik, Hüseyin Gökdemir , "The Impact of Transparency Ratio on Thermal Comfort: A Field Study on Educational Building," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 890 - 897, 2020. DOI: 10.13189/cea.2020.080516.

(b): Fatma Zoroğlu Çağlar, Gülay Zorer Gedik, Hüseyin Gökdemir (2020). The Impact of Transparency Ratio on Thermal Comfort: A Field Study on Educational Building. Civil Engineering and Architecture, 8(5), 890 - 897. DOI: 10.13189/cea.2020.080516.


Abstract The thermal comfort conditions of the educational buildings affect students' attention, focus, perception and learning levels. The design of transparent areas is important in the control of solar radiation affecting thermal comfort conditions. The aim of this study is to determine thermal comfort conditions in classrooms with different transparency ratios and to make suggestions for improvements. Classrooms in the same building on the university campus, in the same direction (south) and with different transparency ratios were determined as study areas. Measurements (PMV-PPD) and surveys (AMV-APD) were carried out during a day in heating period. The thermal comfort conditions were evaluated according to the comfort intervals specified in ASHRAE-55 and ISO-7730 standards. The results showed that there were significant differences in thermal comfort between classrooms. If the transparency ratio is more than necessary, it causes discomfort and redundant energy consumption. Suggestions have been made to ensure solar control and thermal comfort conditions.

Keywords Transparency Ratio, Thermal Comfort, PMV-PPD, AMV-APD, Classrooms

1. IntroductionSolar gains contribute to the cooling load and increase

energy consumption in summer [1]; on the other hand, they

have a positive effect in winter. Transparent areas are the most effective building envelope components in solar gains. The design of transparent areas (transparency ratio, transmission coefficient and use of solar control devices) is important for the control of solar gains.

Short wavelengths of solar radiation passing through the glass turn into long waves as a result of contact with the surfaces in the interior and long wavelengths cannot pass through the glass. As a result of these event, a greenhouse effect occurs and indoor temperature increases. In particular, glazed facades facing south or west (in the northern hemisphere) are particularly vulnerable to overheating, inducing thermal discomfort [2]. Large glazing areas are typical of newly constructed buildings. Solar radiation passes through the glass, warming the environment and causing thermal discomfort especially in large glazed facade buildings. An appropriate transparency ratio improves thermal comfort by controlling solar energy gain and reduces energy consumption.

Thermal discomfort negatively affects students’ learning performance [3]. Providing good environmental conditions for educational buildings is important because of the negative influence of thermal discomfort on students’ and teachers’ learning/teaching performance and health. Their health and wellbeing depend on an appropriate educational environment [4, 5].

According to Turkish Higher Education Council, University students and academics constitute about 9.8% of the population and there were 207 University campuses in Turkey. Students and academicians of 61 universities in


Istanbul constitute 26.3% of this rate [6]. Students and academicians have a significant share in the population and spend most of their time in university buildings. Therefore, appropriate thermal comfort conditions are of great importance for those users.

The influence of the properties of the transparent component on the thermal comfort has been investigated in several studies [1, 7-11].

Although there have been a lot of researches in the transparency ratio and thermal comfort, there are few studies on the evaluation of existing educational buildings with the field studies. This study aims to determine that the thermal comfort conditions depending on the transparency ratio (WWR – Window to Wall Ratio) are different in the existing educational building and to make suggestions for improvement. The thermal comfort conditions in the university classrooms with different transparency ratios were determined by the objective (measurement) and subjective (survey) methods. PMV (Predicted Mean Vote) and PPD (Predicted Percentage of Dissatisfied) values obtained as a result of the measurements and AMV (Actual Mean Vote) and APD (Actual Percentage of Dissatisfied) values obtained as a result of the surveys were evaluated according to ASHRAE-55 and ISO 7730 standards. As a result, it was determined that there were significant differences in thermal comfort between classrooms. If the transparency ratio is more than necessary, it causes discomfort and redundant energy consumption. Suggestions have been made to improve the thermal comfort of the existing educational buildings depending on the transparency ratio and to reduce energy consumption. If integrated with other similar works, these results can be exploited to design of transparent areas of existing or in design phase educational building.

2. Method It was decided to conduct field studies in an existing

educational building in Istanbul (temperate-humid climate) on transparency ratio (WWR – Window to Wall Ratio) and thermal comfort as a result of the literature studies. Classrooms are determined as study areas in the same building (on the 4th and 5 floors) on the university campus, in the same direction (south) and with different transparency ratios (other properties of the volume are the same). Measurements (objective method) and surveys (subjective method) were carried out at the same time during a day in the heating period. While the field study was conducted, the heating system was completely off at all the rooms. The measurements were performed with Testo 480 - Digital Temperature and Humidity Meter. The survey results were analyzed using SPSS 22 (Statistical Package for the Social Sciences). PMV-PPD and AMV-APD data were obtained as a result of measurements and surveys, respectively. Results were evaluated according to ASHRAE 55 and ISO 7730

standards with table and graphic methods. Suggestions were presented for determining and improving thermal comfort conditions in classrooms with different transparency ratios.

2.1. Transparency Ratio on Thermal Comfort

The satisfaction of an individual with the thermal environment is defined as thermal comfort [12]. When a building is designed by evaluating outdoor climatic conditions, indoor thermal comfort can be achieved with less energy consumption. Outdoor climate conditions depend on factors such as air temperature, solar radiation, humidity, and air velocity. Indoor thermal comfort depends on objective and subjective parameters. Objective parameters are determined as indoor air temperature, mean radiant temperature, relative humidity, air velocity, activity level, and clothing insulation level. Subjective parameters are factors that vary individually and can be listed as age, gender, weight (subcutaneous fat), and health status etc. [13]. One of the most effective outdoor climate conditions in thermal comfort is solar radiation. The heating of the indoor environment with solar gains is very fast and effective especially in buildings with large transparent areas because of the occurring greenhouse effect.

Transparent areas are thin, impermeable surface and they have a high U value and low time delay, compared with opaque areas. For this reason, the transparent areas have the fastest and most effective heat gain-loss and condensation in the building envelope. The design of transparent areas is very important in terms of its effect on thermal comfort. This study focused mainly on determining the effect of solar radiation gain provided through transparent areas on thermal comfort.

3. Determination of the Field Study Conditions

Thermal comfort conditions play an important role in efficiency and health in educational buildings. Istanbul is the province with the highest number of universities, students and academicians in Turkey. İstanbul has a temperate-humid climate. The existing educational building to be studied has been selected at a university campus in Istanbul.

The southern facade is the most effective facade in solar gains. For this reason, classrooms with transparent areas on the south side have been determined. Since thermal comfort depends on many factors, the other properties of the classrooms (environmental conditions, orientation, room dimensions, height above sea level, the building envelope properties, the material properties, etc.) are as similar as possible.

The field study was conducted on Yıldız Technical

892 The Impact of Transparency Ratio on Thermal Comfort: A Field Study on Educational Building

University, B block, classrooms B-502, B-503, B-402 and B-403 (Fig 1.). The classrooms are on the 4th and 5th floors. There is no obstacle that prevents daylighting from the south in the classrooms. The properties of the classrooms are given in table 1.

The building envelope (opaque and transparent components) material properties (U value, g value etc.) of

the determined classrooms are the same. The U value of glass determined as 1,84 W/m2K and the U-value of the exterior wall determined as 0,38 W/m2K by measurement with Testo 635-2. Transparency ratios (WWR – Window to Wall Ratio) of classrooms are given in table 2. The difference between the transparency ratios of the southern facades is quite large.

Figure 1. Exterior and interior of classrooms and measurement device (B-402)

Table 1. Properties of Classrooms

Classrooms Direction of classroom Dimensions Heating system and number of Radiator Capacity

(person)

B 502 South 11,76 × 8,90 × (2,7-3,80) Trapezoidal Prism

Gas central heating systems, Cast iron radiator- 3 radiators 109

B 503 South and West 11,76 × 9,08 × (2,7-3,80) Trapezoidal Prism


B 402 South 13,26 × 8,90 × (2,7-3,80) Trapezoidal Prism


B 403 South and West 13,26 × 9,08 × (2,7-3,80) Trapezoidal Prism


Table 2. Properties of transparent component

Classrooms Direction of transparent component

Transparency ratio (WWR – Window to Wall Ratio)

South West East

B 502 South %60 - -

B 503 South and west %60 %11,5 -

B 402 South, west and east %7,5 %6 %6

B 403 South, west and east %7,5 %11,5 %6


3.1. Determination of the Outdoor Weather Conditions

It is necessary to know the outdoor weather conditions affecting the thermal comfort of the indoor environments in order to make the correct assessment. Outdoor measurements were made on the measurement day, keeping the measurement parameters the same. Measurements were made in clear sky conditions, on sunny days and in an open area. Data on the outdoor weather conditions within the campus in Istanbul (which has a temperate humid climate) where the study is conducted is given in table 3.

Table 3. Outdoor weather conditions of the field study days

Date Time Air

Temperature (°C)

Relative Humidity

(%rH)

Air Velocity

(m/s)

20.12.19 15.50 15,2 68,7 1,4

3.2. Determination of the Thermal Comfort Conditions

Thermal comfort may be determined with different methods. Most common practices are objective (measurement) and subjective (survey) methods. Both methods used in this study for comparing the results and determining the thermal comfort in the most accurate way.

Field studies were carried out in the heating period on 20.12.2019. The southern facade of the buildings in the 41st latitude (latitude of Istanbul) is exposed to direct sunlight between about 10.00-16.00 on the field study day. Therefore, field study hours are determined between 12.00 and 16.00.

Measurement studies were conducted on four different unoccupied (no occupant) classrooms and were repeated while classroom B-502 was occupied (with occupant). In order to determine the effect of transparency ratio on thermal comfort, the most important points in the plan are the closest and farthest distance to the transparent area. Three points were determined in each classroom for measurements (Fig. 2). While the field study was conducted, the radiators (heating system) were completely closed, the curtains were open and the windows and doors

were closed at all the rooms. The measurements were performed with Testo 480 -

Digital Temperature and Humidity Meter (Fig. 1) [14]. This device gives the thermal comfort values as PMV and PPD according to the input data and the instantaneous values of the objective parameters. The required data for the measurements are determined according to the ISO 7730, ASHRAE 55 standards [12, 15], survey results and literature (Table 4). The clothing insulation level was determined as 0.7 clo according to the surveys. The activity level was determined as 1.2 met [12, 15] and the measurement height was determined as 1.1 m [12] according to the standards. The measurements were carried out for 5 minutes at 30-second intervals at each point after the device was installed and held 5 minutes.

Survey questions were prepared using the ISO 10551, ISO 7730 and ASHRAE 55 standard [12,15,16]. Clothing insulation levels (clo) were determined by observation-based table processing and calculation. The survey results were analyzed using SPSS 22 (Statistical Package for the Social Sciences). AMV and APD obtained from the question related to the seven-point thermal sensation scale in the survey.

In order to determine the thermal comfort, PMV - PPD and AMV - APD values are used. According to measurement and survey results, it is determined whether the environment is comfortable by comparing with the values given in ISO 7730 and ASHRAE 55 standards. Classification regarding the PMV and PPD values that describe the satisfaction state according to ASHRAE 55 and ISO 7730 Standards is given in Table 5 [12,15].

-0,5<PMV<+0,5 range is considered as comfortable according to ISO 7730 and ASHRAE 55 standards. This range means 10% PPD value [12,15]. The closer the PMV is to 0, it means the more comfortable the environment. PMV obtained from measurements was evaluated according to this range. -1<AMV<+1 range is considered as comfortable [12,15]. The closer the AMV is to 0, it means the more comfortable the environment. AMV obtained from survey question which is related to seven-point thermal sensation scale was evaluated according to this range.


Figure 2. Plans and measurement points of classrooms

Table 4. Measurement conditions of the classrooms

Point Number for Each Classroom

Measurement Device Height

Measurement Type-Duration-Period

Activity Level

Clothing Insulation Level

3 point 1,1 meter According to time - 5 min - 30 sec 1,2 met 0,7 clo

Table 5. Categories of thermal environment

Category ISO 7730 ASHRAE 55

PPD PMV PPD PMV

A (I) 6% ±0.2 10% ±0.5

B (II) 10% ±0.5 20% ±0.85

C (III) 15% ±0.7 - -

Figure 3. Measurement results in unoccupied classrooms


4. Results

4.1. Measurements Results

The results of the field study were analysed by classrooms and points. Measurement results of classrooms B-402, B-403 and B-502, B-503 are given in Figure 3.

Evaluation of thermal comfort in classrooms B-402 and B-403;

PMV is on the hot side and is within the comfort limits in both classrooms.

The 3rd point is the most uncomfortable point in both classrooms.

Classroom B-403 is more uncomfortable than classroom B-402 for all three points.

Evaluation of thermal comfort in classrooms B-502 and B-503;

PMV is on the cold side at 4th and 7th points in classroom B-502, and at 4th point in classroom B-503.

The 3rd point is uncomfortable on the hot side but PMV values of the other points are within the comfort limits in classroom B-503.

Comparison of classrooms B-402, B-403 and B-502, B-503;

When the PMV values of the 3rd point are compared, it is determined that there are big differences between

the classrooms B-402, B-502 and between classrooms B-403, B-503.

While the PMV is within the comfort limits in the classrooms B-402, B-403, B-502, it is determined that the comfort limits mostly exceeded on the hot side on the 3rd point in the classroom B-503.

The difference in PMV values between 4th, 7th points and 3rd point in classrooms B-502 and B-503 are quite large. However, PMV values between points in classrooms B-402 and B-403 are closer to each other.

The PMV values are cold side in points far from the window in classrooms B-502 and B-503. However, the PMV values are hot side at all points in classrooms B-402 and B-403.

Evaluation of thermal comfort of unoccupied (no occupant) and occupied (with occupant) classroom;

Measurement studies were conducted on both unoccupied (no occupant) and occupied (with occupant) classroom B-502 conditions. When measurements were made, there were 70 people in the classroom B-502. Measurement results of occupied and unoccupied classroom B-502 are given in Figure 4. When there is no occupant in the classroom, PMV is

within the comfort limits. When occupants are in the classroom PMV is on the hot side in all three points and outside the comfort limits in the 3rd and 4th points.

When occupants are in the classroom (70 people), PMV increases at all three points on the hot side. The increase on the hot side is the most at the 3rd point.

Figure 4. Measurement results in occupied and unoccupied classroom B-502


4.2. Survey Results

In order to obtain reliable and accurate results, it is necessary to determine the clothing insulation levels before the measurements [17]. Therefore, a detailed table has been created to determine the clothing insulation level before measurements. The mean clothing insulation level of 62 students was determined to be 0.73 clo with 2-day observation-based table processing and calculation in front of the classrooms in the study area.

The planned process for conducting surveys could not be completed because the international negative situation arose and the universities continue their education with remote access in the spring period of 2019-2020. For this reason, the study could not be repeated and the data of the surveys conducted with few students were shared.

The surveys including questions about thermal comfort were made in classroom B-503 and 11 undergraduate students (6 males and 5 females) participated. It was determined that 54.5% of the students sat at the 4th point during the lesson. 90.9% of the students stated that their time in the classroom was more than 30 minutes. 54.5% of the occupants stated that sense of thermal comfort is neutral. AMV value is 0,18 and APD value is 9,1 according to survey results. -1<AMV<+1 range is considered as comfortable according to ISO 7730 and ASHRAE 55 standards. Occupants have felt neutral according to AMV and APD values.

5. Discussion and Conclusions Occupants’ satisfaction in terms of thermal comfort is

important to increase efficiency in educational buildings which students and academicians are the main users. It was determined that the effect of transparency ratio on thermal comfort is quite high in the existing educational building. As a result of the field study, it is determined that the classrooms with low transparency ratio are more comfortable. The high transparency ratio caused classrooms to overheat and uncomfortable. The PMV value of the point close to the window was

higher than the other points because of solar radiation. The difference between PMV values of points close to

the window and far from the window is quite high in classrooms with a high transparency ratio.

There are not many differences in thermal comfort between the points in the classrooms with a low transparency ratio.

It was determined that PMV values increased on the hot side while the classroom B-502 was occupied. When the classroom was unoccupied, the PMV values were within the comfort limits, while the classroom was occupied, the PMV values exceeded the comfort limits at some points. The highest increase in PMV values was the point close to the

window when the classroom was occupied and this difference was quite high.

As a result of surveys, occupants felt neutral according to AMV and APD values. The majority of users stated that they were sitting at the 4th point during the lesson, which was also comfortable in the measurement results.

The radiators were completely closed during the field study, however, normally radiators are kept open. The comfort situation in the classrooms was mostly on the hot side even when the radiators were closed. It is shown that there is unnecessary energy consumption in these classrooms. It is suggested that planning for HVAC systems should be done separately for each room, and if not possible, the rooms should be classified as north and south.

It will be an economical and effective solution to use shading devices in the southern facade of classrooms with high transparency ratios (causing thermal discomfort) such as the existing classrooms studied. With the correct use of shading devices, solar control is provided and energy consumption is reduced while providing thermal comfort conditions during heating-cooling periods. In addition, with the correct use of shading elements, daylight is also used, which can reduce energy consumption.

This study is different from other studies since field studies were conducted in an educational building in the temperate humid climate. If integrated with other similar works, results and suggestions of this study can be exploited to design of transparent areas of existing or in design phase educational building. The results would be different for buildings located in different climates, in different directions and having different functions. The analysis must be made for each building separately in the design phase. It is necessary to determine the transparency ratios, depending on the function, by considering the thermal comfort as well as the visual and acoustic comfort at the design stage. More extensive studies can be carried out by using the method of this study and combining it with visual comfort. In this study, where the effect of transparency ratio on thermal comfort is determined, the awareness of architects and engineers on the subject are expected to increase.

Acknowledgements This research did not receive any specific grant from

funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of Interests The Authors declare no conflict of interest.


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[8] A.R. Amaral, E. Rodrigues, A.R. Gaspar, & A. Gomes. A thermal performance parametric study of window type, orientation, size and shadowing effect. Sustainable Cities and Society, 26, 456–465, 2016. https://doi.org/10.1016/j.scs.2016.05.014

[9] T. Ashrafian & N. Moazzen. The impact of glazing ratio and

window configuration on occupants’ comfort and energy demand: The case study of a school building in Eskisehir, Turkey. Sustainable Cities and Society, 47, 2019. https://doi.org/10.1016/j.scs.2019.101483

[10] H. Bernardo, C.H. Antunes, A. Gaspar, L.D. Pereira & M. Gameiro da Silva. An approach for energy performance and indoor climate assessment in a Portuguese school building. Sustainable Cities and Society, 30, 184–194, 2017. https://doi.org/10.1016/j.scs.2016.12.014

[11] Z.S. Zomorodian & M. Tahsildoost. Assessment of window performance in classrooms by long term spatial comfort metrics. Energy and Buildings, 134, 80–93, 2017. https://doi.org/10.1016/j.enbuild.2016.10.018

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Socio-economic and Geo-political Transitions in the Mediterranean Basin and Its Impact on Urban

Forms of Port Cities

Husam R. Husain1,*, Hassina Nafa2

1Architecture and Urban Design Program, German University in Cairo, Cairo, Egypt 2Department of Architecture, Girne American University, Girne, N. Cyprus


Cite This Paper in the following Citation Styles (a): [1] Husam R. Husain, Hassina Nafa , "Socio-economic and Geo-political Transitions in the Mediterranean Basin and Its Impact on Urban Forms of Port Cities," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 898 - 907, 2020. DOI: 10.13189/cea.2020.080517.

(b): Husam R. Husain, Hassina Nafa (2020). Socio-economic and Geo-political Transitions in the Mediterranean Basin and Its Impact on Urban Forms of Port Cities. Civil Engineering and Architecture, 8(5), 898 - 907. DOI: 10.13189/cea.2020.080517.


Abstract In the last decades, the Mediterranean region is experiencing economic, social, and spatial changes in its structures. Today, cities are experiencing an increasing number of complex problems regarding internal and external connections, reflecting on the city structural realm. The physical transformation of territories in general and cities in particular are associated with external trends, such as migration, post-colonization affects, social changes, economic, and political activities. The paper concludes how coastlines act as an interface between internal and external transitions of the Mediterranean region, and highlights those territories as important defensive lines which could embrace the Mediterranean challenges. The attitude of coastlines as a system basis of cities can find a compelling rationale as well as a cohesive meaning of recovering its major role in embracing complex external and internal relations, which result in the formation of a strong and coherent urban system to cope with constant transitions of the region.

Keywords Urban Evolution, Transformation, Urban Trends, Mediterranean Region

1. IntroductionThe location of the Mediterranean Sea has always been a

transitional hub of economy and culture, which played a prime role in increasing the rates of population and urbanization in the Urban Mediterranean region. The economic and governor status of the region made it clear that the proportion between the rate of population and growth of cities is in direct relation to the urban history and the location of cities on the world map. In the 21st century, the socio-economic and geo-political experiences are constantly transforming the physical spatial structure of cities, whereas their images are being seen within a wider lens; a perspective that consists of internal local transitions, and external influences and forces which shape their structure.

The social transformation of the Mediterranean region in the last decades has given a prime significance to the coastal cities over hinterlands due to their geographic location as a transitional hub and a major link between hinterlands and linear coastal connections of a particular Mediterranean strip, especially that these cities became a prime destination for people migrating because of several social, economic and political concerns.

Subsequently, the world is about to enter a post urban era, where cities do not anymore indicate their own local significance, instead; they become sub-structures within a wider regional and territorial transformation parameter. This territorial structure is characterized by the relation and the connection between cities and regions, rather than a


case-by-case cities’ transitional factor. In view of that, this study suggests that the Mediterranean coast is a common analytical element within a larger frame represented by the connections between different Mediterranean regions.

2. Urban Transformation Drivers In the 19th century, ports construction was undertaken

in great cities in the hope to cope with the industrial boom, while small cities where still in the need to moderate their infrastructure and facilities. Consequently, the economic activities were reoriented towards the coast and hence the external world. Therefore, the construction of ports around the Mediterranean fostered the transformation of the physical structures of port cities, and led to raise new social and economic trends with it. The projection of these activities can be seen in the form of physical transformation in the urban structure of cities [1].

With the advent of the third millennium, the population of cities has surpassed the rural, with over than 50 percent of the world’s population living in urban areas [2]. Today, with the increasing urban challenges related to global socio-economic and geo-political statuses, many cities and towns are experiencing an increasing number of complex problems regarding internal relationships and external connections. These problems are uprising from wars, colonization, and urbanization, thus rapid transitions in structural realm of cities are being witnessed over the last two decades.

Globalization, which produces major international networks between different territories, opened the door for new urban regional delineation to fulfill the development needs of cities around the world, particularly with the centralization strategies of great cities, which places great responsibilities on governments and local institutes.

The global urban concentration in the late 20th century was typically on cities with significant population and regional spatiality, whereas little towns (in terms of the number of inhabitants) have been neglected in spite of their role in the transformation process between major cities, besides their important role they played being transitional bridges between the coast and hinterlands. However, the importance of these towns has arisen significance to face the urban challenges of the 21st century, mainly the interfaces of the Mediterranean coastal zones.

3. Urban Transformations of Ports Dynamics

The industrial revolution in the 18th and 19th centuries produced the greatest transition in human history [2,3]. This transition is remarkable through an effective separation between work, study, and residence. Natural

growth in both urban and rural areas has begun to lose its prestige due to the growing desire to cope with the growing pace of population and urban demands, as well as the desire to follow up with the industrial production around the world. This has resulted in unequal local population distribution between urban and rural areas, whereas the global up-growing industrial trends in the last decades re-shaped the urban distribution amongst cities.

4. Materials and Methods Many cities centered on the Mediterranean Sea had

varying influence roles in the form of the general economy of the entire region through its strategic location that dominated global trading routes in the past, and other social and political factors at the present time. These cities took advantage of their position to develop future strategies by partially or completely transforming their infrastructure, which leads to changing the city’s shape and its main function to provide equal economic and social opportunities for its residents. The selected case studies are Limassol and Famagusta in Cyprus, Corinth in Greece and Beirut in Lebanon. According to their different locations, these cities represent varying compositions within the Mediterranean region; Famagusta, Limassol, and Beirut are on the continuous coast of the Mediterranean, whilst Corinth and Isthmia are connected via the Corinth Canal to the Mediterranean Sea. Therefore, two models were analyzed to coherently conduct the study of the region mainly the coastal and the artificial link. Further, these cities present a comprehensive view of the Mediterranean region from their strategic locations which represent a holistic overview of socio-economic and geo-political factors that are affecting these cities positively or negatively over time.

4.1. Positioning and Economic Parameters

The city of Limassol in Cyprus is an explicit example of the impact of global economic and territorial social transitions on coastal cities. In 1979, the expansion of the city began to flourish and the increase overtook the neighbouring villages. After the construction of the new port in 1937, the economic activities of the old port which was considered the largest on the Mediterranean trade lines began to decline rapidly. Therefore, major changes occurred in the infrastructure, because the old port, which was located in an important historical centre, lost its economic and social role that was considered the main transportation and economic centre for the region as a whole. The old economic centre did not only have commercial and cultural significance, it also acted as a social disseminator. The lower social classes of the population lived in the southern part of the city around the port, working in harbour related activities, while the

900 Socio-economic and Geo-political Transitions in the Mediterranean Basin and Its Impact on Urban Forms of Port Cities

wealthier class lived in the north and in the centre, where Limassol’s coast was mostly shops, and some residential areas in the West and warehouses in the East. However, with the considerable increasing rate of touristic activities over the past 25 years, a noticeable change occurred on the waterfront in relation to both land use and residential buildings’ typologies. Therefore, the wealthy class started to trace over low social classes’ lands, hence the whole coastline is today fully occupied with new projects which consist of shops, recreational areas, and middle and high-residential buildings [4].

The strategic location of the city, facing African, Asian, and European Mediterranean coastlines, acted as a major factor in the emergence of port-city notion in relation to the external world. This has directly affected the formation of the city spatially and functionally. Therefore, due to the regional central focus it played overtime, Limassol was a factor for both the thriving and further development of the new port. In 2017, it further expanded by constructing a new cruise terminal to accommodate the

largest cruise vessels. The port’s development doesn’t seem to be stopping in the near future but rather prospering [5].

The previous changes that occurred in the port of Limassol were one of the factors that affect changing the shape and functions of the coast, hence the city. The city today extends from east to west further than 15 km along the coast with the newly developed corridors and parks. Nonetheless, following the industrial and commercial activities along the coast, the distribution of land-use has a major influence on the shape of the city. Poor and massive coastal developments have caused problems such as coastal erosion due to slow government measures to provide solutions, therefore citizens tend to resort to illegal solutions such as vertical wave barriers created in the hope to improve and protect beaches. As a result, the physical network of Limassol gives a comprehensive overview on the morphological transitions of the city, with multiple urban fabrics nowadays as shown in Figure 1 below.

Figure 1. Different fabrics present in Limassol


“Previous spatial analyses of Limassol’s growth have pointed out that uncontrolled urban development led to an uneven expansion of the city, creating a fragmented structure and leaving many gaps in the urban fabric” [6].

The main drivers of the growth in the city are represented by the radial network which connects the Eastern side of the coast to the western side. The formation of this network was based on the central historic core. The hierarchy of the network is presented by main roads perpendicular to the coastline and radial roads around the old port with organic secondary streets in the parcels created in-between. Furthermore, the fabric of the city around the coastline indicates that the densest urban area of the city is located directly above the old port where the city first emerged. This gives an insight of the importance of the historic centre and the old port, which was dominating the central coastal zone of the city.

The exact opposite of the case of Limassol, on the northern Mediterranean Sea bank where Greece is located, the city of Corinth suffered from severe collusion in the population and urban growth after the construction of the Corinth Canal. After the earthquake in 1858 resulting in the destruction of what is now called Ancient Corinth, The Municipal General Plan of the same year was developed over the vision of building a new city around a small harbour. The strategic location of the city on the Isthmus

region that connects the Gulf of Corinth with the Mediterranean Sea promised economic success along with a port that will open up new commercial opportunities. However, the economic significance of the newly built city indicates a lot less than it used be in the ancient era [7].

Corinth location on the coastline of the Gulf of Corinth and its port being close to the Corinth Canal entrance might have promised economic success to the city; however, according to Mambra [8], once the canal was constructed, it was not economically successful as expected earlier; It was difficult to navigate through the canal due to its narrowness and the frequent high winds and strong currents. Another reason that hindered the success of the canal is being located in an area of high seismicity. High seismicity in the nearby area of the Corinth Canal caused slope instabilities especially at the sites of the slopes that are characterized with low safety factor [9].

Therefore, this determines two important factors in the development of cities in the post-industrial era; first building ports for economic and political purposes, and exploitation of the location. However, visions differ, and misuse of geographical features may lead to urban disasters, as witnessed in the case of Corinth.

Figure 2. Influencial economic elements impacting on the Corinth region


4.2. Geopolitical Transitions and Their Impact on Social Solidarity

The average population density in coastal areas is about 80 persons per square kilometre, twice the world’s average population density [10]. Kostof [11] acclaimed that clean running water is the most critical aspect for human settlements, for example, around the Nile River; the density is in the average of 750 people per kilometre square. Therefore, the social aspect and the geographical context play a major role in the urban development of the coastal areas. Subsequently, investments in infrastructure increase with the growing demand, hence the need for better urban qualities triggers. This process of regeneration and expansion differs from a place to another, resulting in the formation of various new urban patterns.

The dislocation between coastal cities and hinterlands does not only have an economic, social and geographical dimensions, it has also increased physical independency from one city to another. In the last decades, cities became more connected socially and hence physically due to immigration and multiple social factors. The morphologies for the origins of urbanism are not limited to the local internal distribution of population within cities, rather, they also include several multidimensional aspects such as the military actions, political forces and sociological human responses with religious reasons, which led to more infrastructure needs through a heavy

bureaucracy [11]. The city of Famagusta in the southern east coast of

Cyprus is one of the most prominent examples in the Mediterranean Sea which reflects a major physical transition due to external socio-political factors. The city developed from ancient times near the coast, where it was known mainly for fishing as well as being an important trading hub. The growth of the city was affected after the division of the island of Cyprus (Figure 3). As the growth of the city was shaken by the establishment of military areas along the coast, these changes occurred in the city's early form, and as a result, it has shifted from an economically self-contained village to a more complex structure of social and political dynamics.

Therefore, a dramatic transition in Famagusta’s urban realm occurred due to the geo-political role responding to the socio-economic needs of the Mediterranean region. The city, which was originally founded as a small fishing town around 300 BC, and later became an important commercial coast, suffered from the incident that marks the beginning of the spatial separation between Greek and Turkish Cypriots. Since then, Famagusta has lost its significance as a coastal city, and the importance of the city has shifted to be a response to migration beginning in 1986 when the University of the Eastern Mediterranean was founded, which led to massive unplanned urban growth (Figure 4).

Figure 3. The island of Cyprus before and after division showing social segregation


Figure 4. Urban Development of Famagusta


Nowadays, Famagusta’s economy suffers from the loss of attraction towards the port which became a marginalized priority due to the re-configuration of urban growth, this was mainly affected after the evacuation of “Verosha” city in 1974 and the closure of the coast on the western side. Further, the rapid increase of foreigners migrating after the establishment of the Eastern Mediterranean University, which today shapes one third of the overall population of the city, generated unexpected consequences [12]. The city was not prepared to this transition in social structure, thus urban patterns and population distribution were scattered with no clear vision on how to cope with the increasing demands. Subsequently, authorities developed social housing projects that also caused uncontrolled and unorganized development and more consumption of available land resources.

In regards to touristic activities, in the past those were mostly condensed in the old city, because of the port and its identity as a historical core, and Varosha being the most attractive place along the Mediterranean Sea. However, in the current situation, the cultural and historical based-tourism shifted into educational tourism, mostly located around the university [13,14].

In 1967, the old port had a major impact on urban development in Famagusta, which resulted in the fusion of the old city, and the formation of the rest of the city. On the contrary, the waterfront was affected by the new developments. The socio-economic prosperity owed to the Eastern Mediterranean University, has had a major impact on the development of new areas along the coast, and on the form and overall direction of these developments.

Likewise, Beirut city on the opposite bank of the Mediterranean suffered from similar socio-political concerns. In 1920, the demographics of Beirut were boosted by the massive number of refugees displaced from different areas. Christian communities of Turkish and Armenians migrated into Beirut, followed by Syrians, Kurdish and Palestinians after the Israel-Arab war in 1967. Following that, around one million people relocated from rural areas to Beirut suburbs, and accordingly, about 50% of the overall population of Lebanon was living in Beirut in 1975. All of Lebanese and Non-Lebanese migrants lived in settlements on the outskirts of Beirut.

In spring 1975, Beirut witnessed the division between East and West. The Old Damascus Road demarcated the limits between Beirut’s two new parts. It became known as the ‘green line’ or the ‘demarcation line’. The zone was a buffer land during the cold war and a confrontation line during heated episodes. Downtown was also one of the main challenges, as almost all buildings were demolished, and serious damage along the demarcation line was assessed at 80%.

Beirut came out of the war period in 1990 naked; a total disaster and a total desolation. The reconstruction proposals were mainly oriented to restore the

characteristics of the Mediterranean city. The main idea was included restorations of commercial strips and to open up the city to the waterfront, whilst the other side of the project was to give a modern character to the city; it contained community buildings that symbolize the unity of the country [15].

In the post war era, Beirut began instantly to recover. All demolitions, repairs, re-buildings were launched. The government at the time was establishing the Solider Company, and it started to execute some of the main elements of the transformation of Beirut’s downtown; renovation and recreation of much of the built fabric in the historic sectors. The demolition of the area of high symbolic significance demanded essential renovations, especially for the downtown which is the heart of Beirut.

The CDB was expected to provide a concrete way out of the social crisis, the reconstruction of the downtown area was expected to revitalize the economic situation of the city, especially after the war, through adding a modern character to the historical context which was in need of transformation [16].

Beirut was strongly affected after the war and the way the reconstructions were contrived had negative side in the long term. It is clearly shown how the regeneration plan did not tackle the social segregation as there are some clear places still segregated for Muslims-Shi’a only, Muslim-Sunni only and Christians only.

5. Discussion and Conclusions: The Mediterranean Conceptualized

The purpose of the study is to deepen the perspective on the physical transformation of Mediterranean territories in general and cities in particular which are associated with external trends, such as migration, post-colonization affects, social changes, economic and political activities. The Successive urban typologies of cities are in fact a direct response to the emergence and constant changes of socio-economic and geo-political conditions of the whole region. These changes were reflected on land-use, social classes distribution, economic indicators, political conflicts, and often result in unplanned sprawl.

As a result, this study emphasises that economic growth of ports is directly related to the evolution of cities around water bodies. The linkage between ports and coastline has ever been crucial in the evolution of Mediterranean coastal cities. The function of ports and their economic statuses affect the coastline and hence the growth, land values, and shape of the city as a whole.

It is evident that tourists flow usually occurs around focal points of the city; therefore, historical and cultural tourism is not anymore the driver of tourism-based economy, such as in the case of the university in Famagusta. These focal emerging elements represent a new form of touristic attraction. Thus, in the


Mediterranean region circumstances, the study finds out that any new development might re-shape the fabric of the city in different forms. It is clearly noticeable how the coastline has lost its significance in the last century. Therefore, in order for cities to revive their significance, it is important to recover the role of coasts as the prime element and core of development, instead of investing coastal resources on touristic attractions which does not provide a long term strategic and comprehensible economical vision, rather, it mainly concerns with seasonal income, which might change due to diverse circumstances. Bearing this in mind, coastal cities are required to revive back their importance; implying that all the unused areas along the coast should repossess their valuable attractiveness. The study suggests that the unused brownfields should recover their role as the core of any future development. Nonetheless, in order to prevent further negative sprawl implied from the de-centralized planning actions, new building regulations that limit the built-up area, set-backs, and provide mixed-use functions should be set accordingly.

Cities today are represented by large number of foreigners who in fact control a large percentage of social and economic rates with students, labour, and political immigrants representing the new concept of globalization in the region. Furthermore, some regions, such as some parts of the northern Mediterranean coast that experienced no urban expansion in the last few decades, is related to the declination of its population. The reason of the declining population is due to poor economic situations.

It can be concluded that the economic situation of the coastal cities is weaker than it used to be before the 20th century, thus the urban expansion is being hindered. Although the overall population of the region is rapidly increasing, yet the declination of the population in the past decades on some cities, such as Corinth region, is declining rapidly. This means that the population is concentrated in limited areas which challenges cities in dealing with infrastructure, meeting the demands for food, water, energy consumption, and environmental concerns. These and added effects have direct impact on the physical growth of cities, as well as the overall economic and political status of the Mediterranean region as a

whole. The regional effect in terms of the economic

importance of the ports and canals, and the population declination directly affected coastal lines by emerging urban fabrics that are neither coherent with the original grid of the city nor having any connection to hinterlands from one side, and the sufficient role in the sea trading activities from the other side, leaving coastlines at a critical point which raises still many critical questions. Beirut is an explicit example of the transformation of urban fabric due to the changing visions of the city (Figure 5), resulted from the internal social segregation which attracted external investments aiming for economic profit only.

The discussion shows how coastlines act as an interface between internal and external transitions of the Mediterranean region, which is in fact a rich dynamic complexity. In this context, the attitude of coastlines as a system basis of cities can find a compelling rationale as well as a cohesive meaning of recovering its major role in embracing complex external and internal relations, which result in the formation of a strong and coherent urban system to cope with constant changes of the whole region.

Urban evolution chronology shows that, while the complexity in the emerging trends in the Mediterranean region is changing every day, the old urban development' elements, such as coastlines, embrace the solution for the transformation in the post-industrial era, through reviving its role as a major hub for socio-economic and geo-political cores.

Therefore, local community institutions of coastal cities, in particular, should start having an effective hand in city planning through initiating joint regional political and economic cooperation to exploit coastal regions, particularly port areas, and involve them in planning strategies in a way that guarantees the social rights of their population, before the greater countries fully revive the exclusive territorial planning vision of the pre-industrial era, which will result in re-opening the door to colonialism, especially in the present day whereas greater countries have indeed begun to connect multi-regionally through global Geo-Economic lines, in a way that was not experienced ever before.


Figure 5. Different Urban Fabric present in Beirut.


Acknowledgements The authors would like to thank Magdi M., ElTonsi A.,

Ahmed Y., Magdy L., Khaled R., Hejazy S., Haroun M., Mohamed S., Bahie N., Mahmoud K., Adel H., ElMasry Y., Amin J., Magd S., Khalil R. for their support with drawings and maps throughout the study.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.


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DOI: 10.13189/cea.2020.080518

Regeneration as a Tool for Enhancing Vitality of

Urban Spaces

Rokhsaneh Rahbarianyazd

Department of Architecture, Alanya Hamdullah Emin Paşa University, Alanya/Antalya, Turkey



(a): [1] Rokhsaneh Rahbarianyazd , "Regeneration as a Tool for Enhancing Vitality of Urban Spaces," Civil Engineering

and Architecture, Vol. 8, No. 5, pp. 908 - 915, 2020. DOI: 10.13189/cea.2020.080518.

(b): Rokhsaneh Rahbarianyazd (2020). Regeneration as a Tool for Enhancing Vitality of Urban Spaces. Civil

Engineering and Architecture, 8(5), 908 - 915. DOI: 10.13189/cea.2020.080518.


Abstract The recent discussion regarding

contemporary urban regeneration has underlined its

increasing role to revive cities. In the mid-19th century, the

process of urban regeneration commenced through

upgrading the already built areas, particularly where there

is evidence of urban deterioration. This study by using

qualitative grounded theory, hypothesized that attaining an

effective urban regeneration involves an increasing quality

of life and vitality. The study revealed that a successful

urban regeneration involves social, environmental and

economic aspects which have been neglected in several

cases of urban regeneration policies. Moreover,

contemporary urban regeneration can rectify the mistakes

of past policies and improve the quality of urban spaces to

where people want to live. In doing so, the study concludes

that to have a successful urban regeneration policy,

different dimensions of urban design need to be considered.

Furthermore, the current study examines the ways in which

urban regeneration is changing the cities and

neighborhoods.

Keywords Urban Regeneration, Vitality, Dimensions

of Urban Design

1. Introduction

All concern for social inclusion in place of exclusion,

re-establishment of social function in the place of

dysfunction, economic revitalization where it was lost; the

restoration of quality and ecological balance in the

environment refer to urban regeneration. Therefore, Couch

and Fraser [7] pointed out that urban regeneration is an

endeavor activity within the horizon of planning and

management of existing urban areas rather than

development of new urbanization.

Accordingly, urban regeneration adduces the

reconstruction, recreating, and renewal of existing urban

areas. It calls attention to adapting new approaches in

reconstructing certain areas. According to Smith [24] and

Roberts [18], urban regeneration is a comprehensive and

integrated approach which seeks to bring about a lasting

improvement in the physical, economic, social and

environmental conditions of an area that has been subject

to change. They highlighted very salient features of urban

regeneration with social, economic, and environmental

imperatives. Within this context, Lichfield [14] provided

further insights and offered an improved understanding of

declining processes that requires regeneration and

awareness of the know-how involved. Other authors such

as Donnison [8] have stated that regeneration is a

coordinated and involved approach to solve problems

which focus on areas where the problems are most intense”.

Donnison [8] and Lichfield [14] went further to argue that

the rationale for concentrating on the problematic areas is

to maintain the required standard for improvement.

Complementing these definitions, Sönmez [25] observed

that urban regeneration is a spatial, economic and social

intervention. On the contrary, however, Couch [5] and

Hausner [13] saw it as simply a succinct synergy of ad hoc

and fragmented physical projects for wider city

development.

Considering above mentioned, it is needful to point out


that vitality has been the missing link in urban regeneration

and related policy formulations. Thus, scholars have

attempted to embed the notion of vitality in the process of

urban design. This study, by considering that urban vitality

is the most rudimentary factor for attaining the quality of

life in the city, stated that urban regeneration policies

should be developed in such a way as to encompass all the

main indicators shaping vitality in the urban environment.

The statement developed in this study will help urban

policy makers reconsider different dimensions of urban

design in conjunction with other dimensions of urban

vitality. It will further assist urban designers in the process

of decision-making become involved with developing a

comprehensive knowledge of how to design vital urban

spaces.

2. Urban Regeneration

Regeneration is the primary instrument of Western cities

to inflect the extant urban form. The term is not only

peculiar to urbanism but it shares biological and religious

nuances. In the biological sciences, urban regeneration

pertains to the re-creation of organic life while it invokes

rebirth in the region. However, both expressions related to

the field of urbanism. The prefix‘re’, has a Latin extraction

and it is inseparably linked with connotations of a new life

for the targeted areas, depending on the context and

definition of regeneration [2]. In Brazil, for instance,

(where regeneration has been coined revitalization), it is

often used to denote the conservation of historic

monuments and sites (Brito citied in Smith [22]). In Britain,

regeneration has seemingly shifted from a regimented and

special targeted conservation-based approach to the

management of whole city areas [19].

In the urban discourse, regeneration has been viewed as

a multi-sided paradigm. In this regard, Roberts & Sykes

[18] posits that “urban regeneration” is an inclusive

long-term approach towards improving the condition of a

declined area. Couch (cited in Dalla Longa [6]) pointed out

that targeted urban regeneration remains a solution to the

challenges that are inextricably linked to globalization such

as ecological and environmental retardations imbalance,

exclusions, as well as economic and social and problems.

Evans & Shaw [10] considered Urban Regeneration as the

transformation of a declined area to a vital one. According

to them, this will involve enhancement of the quality of life,

which will further involve a trade-off in economic,

environmental, and social needs. Contextualizing the

discussion within the domain of urban policy, Smith [21]

viewed regeneration as a break-through in achieving

specific objectives or goals in a declining area. Bianchini [3]

opined that urban regeneration is a complex concept,

involving economic, environmental, social, symbolic,

cultural, and political aspects. Thus, regeneration as an

integrated process is much rooted than minor adjustments

suggesting coordinated area transformation than mere

short-term renovations.

Urban regeneration policies since the 1970s underwent

major changes. The first wave manifested as extensive

physical changes. Indeed, it is a statement of fact that

regeneration was previously associated with economic

imperatives, without the strong need for affiliation with

cultural development. Nonetheless, as more sectors begin

to benefit from regeneration strategies, the term became

more closely associated with the notion of community

development.

Presently, relevant organizations have deliberated the

socio-cultural as well as socio-economic footprints of

regeneration, and although they have not been able to fully

achieve a standardized measure for evaluation, Smith [23]

pointed out that shifts in priorities have been observed.

Peter & Sykes (cited in Balsas [1]) also observed an

ongoing progress in urban regeneration from the rebuilding

of the 1950s to the revitalization in the 60s and renewal in

the 70s to redevelopment in the 80s and finally, to the

regeneration in the 90s [1]. Along this line, it is necessary

to highlight here that the socio-economic changes of the

1980s gradually took away the attention of urban planners

from managing city growth to dealing with economic crisis

[31]. Overall, urban regeneration policies can be classified

into four main waves as illustrated in Figure 1 below.

From Figure 1, it is obvious that form the 1990s, onward

urban regeneration policies become integrated with social,

economic, and physical aspects. Consequently, Roberts &

Sykes [18] maintained that regeneration was associated

with the 1990s particularly when potential methods (then)

were applied to resolve emerging problems of declining

areas [16]. These “potential methods” were frequently the

outcome of vitalizing (usually by bringing new activities)

to the declining area. The 1990s was an era that promoted

vitality of regenerated urban areas using economic, social

and physical aspects of urban life as tools. From Figure 1, it

can also be adduced that the fourth wave of urban

regeneration encompassed all dimensions of the third wave.

Policies advanced from the fourth wave considers as

up-to-the-minute task during urban regeneration process.

910 Regeneration as a Tool for Enhancing Vitality of Urban Spaces

Figure 1. Four main waves in urban regeneration policy

Table 1. Different aspects of Urban Regeneration [23]

Urban regeneration refers to programs or policy

intervention, which may be at different geographical scales

to eliminate problems associated with declining areas.

Smith [23] observed that motivation for implementing

urban regeneration could be wide-ranging from intention to

attract tourist by promoting city image and developing

infrastructure building as catalyst for further development.

However, it should be considered a regeneration scheme

that is sustainable at city scale may not be sustainable at the

local scale, while what may enhance the economic vitality

of an area may damage it environmentally [27]. Table 1

summarize different aspects of urban regeneration.

In addition to the approaches and motivations for

regeneration, there are other coexisting and sometimes

mixed approaches associated with different themes include:

cultural industries development; encouragement and

subsidy; health or community-based development; flagship

or property-led projects; image reconstruction; provision of

infrastructure; area-based improvements; business-driven

interests and developing urban design frameworks [29] [4];

[20]; [11]. Each of these approaches is defined by specific

local governance arrangements. Following these, Roberts

[18] stated five main purposes of urban regeneration:

1. To obtain quality of life and economic development.

2. To correspond to urban needs.

3. To establish a link between social deprivation and

urban physical condition.

4. To show the significance of urban policy application.

5. To sustain the best use of urban land.

There are other cases however where urban regeneration

is sorely aimed at providing short-term physical solutions

to induce gentrification [32]. Gentrification was born with

urban regeneration in the 1960s in Western countries [30].

In respect of this, urban regeneration can be classified in a

plethora of ways, however for this study, Turok’s [26]

classification of ‘place’, ‘people’ and ‘business’ seems

applicable. In terms of people, regeneration aims to

enhance skills, aspirations and capacities to provide the

needed advantage for participating in and benefiting from

opportunities. Amongst others, regeneration further aims to

enhance competitiveness, business performance, the

economic well-being and prosperity of immediate

neighborhoods by improving the physical appeal of the

place.


Aspects of urban regeneration can be classified into the

following mutually exclusive but interconnected ranges:

physical, environmental, governance-related, economic

and social issues. Successful urban regeneration, especially

within local context, recognizes the link between these

aspects. With these considerations, the scope of urban

regeneration can be lengthened over the physical

environment to culture, human resources and values, and

historical essence. The indicators related to the social

dimension should be emphasized in urban regeneration.

Moreover, urban regeneration policies should be

developed in such a way as to enhance people’s interaction

with the environment to increase vitality. To do so it is

necessary to assess the social dimension of urban

regeneration. This is explained below.

2.1. The Social Dimension of Urban Regeneration

The social dimensions of urban regeneration programs

are considered as an important aspect. This includes

enabling an environment for social and economic

opportunities, social inclusion, and reducing multiple

social exclusion [33]. Indeed, according to Ginsburg [12],

social regeneration is inextricably associated with the

prioritization of improved delivery of welfare services in

urban spaces as well as giving autonomy to local

communities to act in the process of regeneration.

Traditionally, social regeneration stems from a

combination of efforts on places (internal investment and

creation of job opportunity, community facilities and better

environment) and/or people (confidence, education

achievement, improving skills and health). Further, Evans

[9],Ginsburg [12] and Della Spina [28] highlighted that

successful social regeneration stems from policies that are

designed to close-in on a plethora of social factors, which

includes bottom-up approaches in the decision-making,

welfare fund for the disadvantaged, and creating

opportunity for sustainable means of livelihood.

Considering the above mentioned, i.e. the social dimension

of urban regeneration, and from a social point of view, it is

obvious that vitality is the main concern of urban

regeneration. Bearing in mind that people and place are two

main concerns within the social dimensions / urban design

framework, vitality is considered as a common objective of

urban regeneration.

3. Vitality

Vitality is a “performance” aspect of urban design with a

capacity to represent the interrelation between forms of

places and to support the capabilities of human beings,

biological requirements and functions. It is a measure to

distinguish social success at urban spaces. According to

Montgomery [15], vitality is an indication of intensiveness

of daily pedestrian flows to which people feel lively in a

place. Urban vitality brings motivation for dynamic

cultural reviews and exchange, promotes the viability of

commercial investments, helps to flatten out cultural

shocks and reduce crime. It has also been found to

associate strongly with urban health index.

In this regard, it is obvious that vitality in a city could

be enhanced if rich assortments of choices and places are

there to experience and feel over different periods [17].

Accordingly, providing the undergirding of urban images,

motivating factors such as street pedestrians and those in

public spaces affect the use of public facilities, programs

and events and foster the diversity of social composition.

In addition, Barry (1988) adjudged vitality as a pointer to

successful urban planning in as much as suitable design

for a public space is considered a congenial apropos to the

needs of its users.

Overall, an extensive qualitative study showed that

there are five main classifications for urban vitality (see

Table 2). To achieve successful urban regeneration policy,

urban designers may need to consider all the leading

dimensions of urban vitality.

Table 2. Five dimensions of urban vitality and leading factors in successful urban regeneration

Dimensions of

Urban Vitality

Factors leading to a successful Urban

regeneration

Cultural

Vitality

Includes respect and appreciation of the

city and its traditions.

Handicrafts, artefacts and symbols.

Functional

Vitality

Ergonomic design.

Functional design.

Social Vitality

Making vibrant society.

Developing community spirit.

Developing opportunities for

involvement of wide range of lifestyles.

Environmental

Vitality

Environmental survival.

legibility, sense of place, safety and

adaptability.

Connectivity and linkage.

Economic

Vitality

Agglomeration of commercial

enterprises.

Market freedom, urban consumption.

Results from Table 2 reveal that vitality is a product of

both the qualitative design in urban spaces of the diversity

of the supported activities and the environment. From the

other side, it should be noted that a more appropriate design

of a public space satisfies more needs of the people.

4. Discussions

Urban regeneration is an integrated and comprehensive

action aimed at providing long-term improvement to the

physical, economic and social dimensions of an

environment [14]. Assessment of indicators and objectives

of urban vitality show that they are following the same

objectives for increasing the quality of urban spaces via

social, economic and environmental factors. In both

approaches, “place” and “people” can distinguish the

nuances toward urban development:


The “Place” on one hand, focus on urban regeneration

development and aim at initiating and/or fostering

economic revitalization through property development

and commercial growth.

The “People” on the other hand, focus on urban

regeneration by giving recourse for avoiding multiple

deprivation through provision of functions for people

from diverse social classification. In this way, it aims at

improving accessibility and enhancing satisfaction. Hence,

equity in distributions of urban public infrastructure is the

dominant objective for regenerating public urban spaces

by referring to people.

Effective strategies for urban vitality based on urban

regeneration policy would preferably include a

compromise of both “place” and ‘people’. This would

provide a way-out than simply gentrifying deprived

communities.

Classification from literature already discussed reveal

four main approaches in urban regeneration. These are

social regeneration, physical regeneration, cultural

regeneration and Economic-led regeneration. In addition,

in reaching the main objectives of urban regeneration, it is

necessary to develop three main policies. In this regard,

Place-oriented strategy mostly deals with physical

improvement and environmental action. Organizational

development deals with the economic revival of a district.

People-oriented strategies require social support to

continue. Social supports equivalent to people-oriented

strategies in most cases are successfully implemented due

to people's involvement. Unlike regeneration exercises

where the people are not considered. The Figure below

illustrates the interrelation of the four main strategies in

urban regeneration with the three main policies in urban

regeneration.

Figure 2. People and place as effective strategies for urban vitality and urban regeneration

Figure 3. The interrelation between approaches in urban regeneration and urban regeneration policies


4.1. Implementing the Concept of Vitality in Urban

Regulation Process

As discussed already, urban regeneration policies need

to consider two main pillars, which are people and place.

Fulfilling all the requirements of people and increasing the

functionality of place to achieve the requirements of

people for their daily activities will lead to successful

urban regeneration and vitality.

Figure 4. The common point where urban vitality emerges

Overall, urban policies should be planned in such a way

as to improve the physical images of places, alleviate

economic and environmental imbalance and provide a

better life for people [18]. If, in a context, vitality

increased, it means that urban regeneration policies have

been successfully implemented. A Successful

implementation of urban regeneration will pass the test of

time. This indicates that the project will survive after

implementation and the potential to continually invite

people will continually invigorate. Providing potentials

for passive and active involvement of people in a place

will also lead to increased vitality of the urban spaces. In

contrast, there are some projects, which might fail through

time. As a result, the rate of crime may increase. This may

also lead to many social and economic problems, which

has negative effects on the vitality of public urban spaces.

Overall, the Figure below reveals two prospective

scenarios for urban regeneration. One may lead to failure,

which is the result of unsuccessful urban regeneration

policies. The other one represents successful urban

regeneration, which is the result of a comprehensive

implementation of urban regeneration polices. This leads

to increasing vitality of urban spaces through the time.

Within declining areas, especially those characterized

by blight, urban regeneration would require community

networking and participation to increase the vitality of

urban spaces. By comparing the five main dimensions of

urban vitality with the four main approaches in urban

regeneration, it is possible to conclude that every

approach has a direct effect on most of the other

dimensions of urban vitality. For example, as illustrated in

Figure 6 below, social regeneration of urban spaces has a

direct effect on economic, social, environment, cultural

and functional vitality of urban spaces. Given this fact, it

is obvious that the urban designer should carefully

consider the four main approaches of urban regeneration

to achieve a much more integrated and successful urban

vitality.

Figure 5. Success and failure of urban regeneration and vitality through


Figure 6. The interrelation between Different approached in urban regeneration and dimensions of urban vitality

5. Conclusions

This paper revealed that urban regeneration aimed at

transforming places and re-constructing traditional

meanings in existing socio-cultural settings. Therefore, the

study posits that in a successful urban regeneration, the

social and psychic meanings invoked by the elements of

the urban environment are overriding and often more

important than the actual physicality of the city imagery.

Furthermore, this research highlighted the importance of

urban regeneration policies in implementing the principles

of vitality in urban environment.

The study further revealed that space-bounded activities

and interactions signalize urban space vitality. Drawing

from this, it follows that the vitality in each spatial unit of

the city or simply space is an indication of the intensity of

human activity. Generally, the study submits that urban

regeneration is an intervention targeted at solving social

and economic urban problems, nonetheless, the objectives

of urban regeneration and employment policies relating to

it are more diverse than only economic environmental or

physical development.

The study also revealed vitality as the fourth wave of

urban regeneration policy, starting from the 20th century.

Today, it is obvious that urban regeneration policies have

been developed in such a way as to increase the vitality of

urban spaces. In this regard, social dimensions of urban

design were considered to study the effects of vitality in

the failure and success of urban regeneration.

Overall, the study disclosed that vitality is a product of

qualitative design of urban spaces and assorted activities

for social, economic, and environmental viability. This

study tries to emphasize that urban policy makers should

consider different dimensions of urban design to have a

comprehensive knowledge of vital urban spaces during

any process of urban regeneration. Hence, an evaluation

of difference between diverse dimensions of urban design

regarding the vitality of urban spaces is recommended for

future research.

Acknowledgements



not-for-profit sectors.


The Author declares there is no conflict of interest.

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https://doi.org/10.25034/ijcua.2018.3659


The Effect of Centrality Values in Urban Gentrification Development: A Case Study of Erbil City

Mustafa Aziz Amen1,*, Hourakhsh A. Nia2

1College of Art and Sciences, Interior Design Faculty, American university of Kurdistan, Duhok, Kurdistan Region, Iraq 2Department of Architecture, Alanya Hamdullah Emin Pasa University, Alanya, Antalya, Turkey


Cite This Paper in the following Citation Styles (a): [1] Mustafa Aziz Amen, Hourakhsh A. Nia , "The Effect of Centrality Values in Urban Gentrification Development: A Case Study of Erbil City," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 916 - 928, 2020. DOI: 10.13189/cea.2020.080519.

(b): Mustafa Aziz Amen, Hourakhsh A. Nia (2020). The Effect of Centrality Values in Urban Gentrification Development: A Case Study of Erbil City. Civil Engineering and Architecture, 8(5), 916- 928. DOI: 10.13189/cea.2020.080519.


Abstract Despite Erbil's citadel significant role in the urban space configuration, it suffers from many functional and accessibility problems, there is rapture in the connectivity, accessibility and visual consistency between the city precinct and the development in the peripheral area, the connectivity of the city could be increased through enhancing centrality of the urban fabric through touristic gentrification. The paper aims to find a way to increase the connectivity between the citadel and its precinct through the touristic gentrification approach. The research adopted the Urban Network Analysis (UNA) technique as a primary methodology for the analysis with its centrality principles. The methodology worked on the urban gentrification process as a way to fill the weak link to increase urban connectivity. The paper found that some areas with high connectivity values in terms of place centrality do not have an equal transformation in terms of land use and importance which accordingly, proposed to be gentrified locations.

Keywords Urban Space, Urban Network Analysis, Gentrification, Precinct, Tourism

1. IntroductionCities are complex entities which composed of several

parts, the different parts of cities are node, path, building, agent and boundary [1], all cities components and parts could be reduced to simple network, building and road

intersection could represent the nodes while the streets represent the connection between the nodes. Accordingly, city parts are connected through spatial joints which become the most significant part in the city, however, some nodes are more important than the other in terms of their implicit centrality values, more specifically have more centrality index than other parts.

To ensure the connectivity of cities, the nodes and links should be connected and be sure that there is a continuity of the centrality spaces connecting the urban layout to avoid zones 'segregation in cities. Traditional cities might suffer from the discontinuity between their diverse parts, especially when there is a new development in the traditional center and precinct's peripheral area, consequently, such parts will suffer from discontinuity and urban fragmentation.

Hence, there is need to understand the links between cities different parts through means of centrality, especially reach centrality that represents the flow of the people between their nodes and the gravity centrality of the space which represent the intention of the urban node to attract more activities and retail through its centrality characteristics, since

"The central spaces are the most reachable spaces in the urban layout, accordingly, the reachability to determine the concentration of the space depends on the number of destinations which is connected to the central node with the reach radius" [1].

Consequently, central spaces are the best spaces to locate new activities and retail in the urban layout to connect cities' different components, accordingly,


gentrification will be the best method to fill that gap and warrant the affluent continuity between cities' different parts.

2. Gentrification's Definition Gentrification is a term used for the influx of

high-income individuals in an existing metropolitan community to improve economic events, wages and land prices, and improvements in the character and culture of the neighborhood. The concept of Gentrification is a process in which members of the upper class migrate into working-class neighborhoods, displace, and alter local populations [2]. The process happens in neighborhoods that have the specific ability to transform, such as diversity and variety of the neighborhood characteristics, as well as the accessibility of the proper or affordable housing, accordingly the availability of the low-price housing and old industrial building attracts new investment and asset to old districts [3].

The gentrification process could be applied to cities with different sizes, consequently, the process is not related to some specific cities or locations, so, the experience is applied to many metropolitan and megacities all over the world, consequently cities like Ciro, Beirut, Barcelona, London, and Berlin. The urban gentrification and urban regeneration for the old cities should include the inhabitant, otherwise, it will be considered as not “Integral” and leave a gap in the urban regeneration process [4].

The objective of the urban gentrification could be reduced to four characteristics as listed below: 1. Demographics: An increase in average income. 2. Real Estate Markets: Large increases in rents and

prices. 3. Transform Land Use: change land use percentage 4. Culture and historical characteristics: Novel ideas

about what is attractive architecture and landscaping [4].

As a result, most of the scholars almost agree on positive impact of the gentrification process, it provides a proper solution for old neighborhoods and reduces the chance for the neighborhood’s deterioration [5]. The different definitions of the word have been clarified according to the scholars in (table 1).

Table 1. The most important studies and the scholars’ description of gentrification Source: The Authors

Year Scholars Description of gentrification

1964 Ruth Glass The urban renovation by transforming the working class with the middle class, as well as renovating the residential uses [6].

1979 Phillip Clay

Classified and introduced different types of gentrification such, as Pioneering, expanding adolescents, and maturing gentrification [7].

1979 Neil Smith

Reinvention of deteriorated neighborhood and encouraging the middle class to move by creating new opportunities through reinvestment [8].

1982 Neil Smith

Transforming land uses and moving middle-class (homebuyers, landlords, and professional developers) to the rundown neighborhoods and replacing the working -class that inhabits the residential area [9].

1996 Ley Moving different parts of social class inside cities according to the sense of place and promoting the urban realm [10].

2003 Lees

Transforming township and suburbs with some apprehension from the differentiation and changes from the “myriad of forms” [11].

2.1. Historical Background and Waves of Gentrification

Glass [6] analyzed and identified the structural and social shifts that took place in certain areas of London in the 1960s, including the movement of low-income working-class people from their modest Victorian homes followed by the demolition of their residences to accommodate higher-class inhabitants in the development of luxurious suburban housing. Hence, Glass [6] realized that gentrification was a phenomenon that grew exponentially and would not deter the city or its elite [3]. Following the same line, Lees argued and defended the concept of 'geography of gentrification' that focuses on the significance of the location and locality, though both Van Criekingen and Decroly proposed a typology of various gentrification types [12]. According to the previous waves, gentrification grew with the districts and had an impact on protecting the developed neighborhood from deteriorating and declining, the different waves with their descriptions are clarified in table 2, where it is clear how each wave stated and worked to modify the different part of the London city.

918 The Effect of Centrality Values in Urban Gentrification Development: A Case Study of Erbil City

Table 2. Waves of Gentrification: Source the Authors

wave Time Description

First Wave 1950- 1973 Transform the working class with new urban “gentry”. Modify the old neighborhood with middle-class people [13].

Second Wave 1970s.

Encourage cultural solutions and create integration between gentrification and new uses like art galleries, museums, and historical preservation [14].

Endorse and encourage integration with financial support from financial institutions and banks, so the whole process started to attract real estate developers and banking finance.

The Third Wave 1990s

The gentrification process becomes a comprehensive process starting from the neighborhood centers to the outward parts in an all-inclusive way.

The gentrification process started to include mega-scale projects and developers. Increment of the gentrification process as the resistance of the process became less and

meager as a result of the continuous movement of the lower class and the workers from the center to the other part of the city [15].

2.2. Gentrification and Tourism

Tourism is the invention of local cultures and historical differences which is compatible and comes close to the visitor’s tastes [3], similarly, the tourism is one of the most significant industries that normally get the support and the backing from the entertainment companies and hotels firms all over the world with a wide range of brand cooperation to renovate a local area into spaces for attracting and consumption [16]. As a result, the tourism industry has a vital effect on cities, nevertheless the traditional parts in cities' centers which contain cities’ traditional area and heritage that needs to be dealt with [17]. Thus, it is logical to provide gentrification locations in the tourism area because those places have the internal influence and effect over all the cities’ different parts, however, the gentrification area with tourism work well in case of combining those variables with the centrality values of the urban layout.

2.3. The Impact of Tourism on City

People practiced tourism industry from a long time, cities have been getting people and visitors for a long time, but, tourism as an urban development approach and direction started to appear and emerge at the beginning of 1990, accordingly scholars started to think about the tourism approach for the urban renovation and regeneration [18]. The concertation of studies on cities’ centers and traditional area makes the scholars forge another word to explain the process that leads to change the urban from and activities in cities’ central parts, the word is “touristification” which is a direct reflection of the demand and understanding of the need to explain the procedure of alteration in urban forms [19]. The procedure had a specific consequence on the “tourist-historic city” whose main purpose is to understand the reflection and the interaction between the place, visitors, and the different activities in the place [17].

The Touristification approach has a many-fold interests and approaches, these include studying the impact of the “destination sites” on the tourism industry, which some scholars called the holistic approach [20]. Similarly some

approaches focus on the economic impact as a major force to attract people and visitors to the destination [21], while some other approaches concentrate on the “events” as the main force in the tourism process such as European Capital of Culture, the attitudes of residents to tourism development issues, that impact the overcrowding perception and experience [22,23], similarly, some approaches focus on alterations in the commercial landscape resulting from the development in tourism [17], finally, there is the social approach which concentrates on the social impact of the tourism with the interaction between the inhabitants and the visitors in the destination area [24].

Since tourism development depends on several values, there is a need to enforce the most important values that regulate the tourism industry, those values are the destination’s characteristics and the number of visitors. Accordingly, those values create an economic, social and physical change and alteration to the place, yet, it is not an obligation to get always positive results following the availability of the previous values which means that sometimes the effect might be positive, while some other time the impact will be negative. Thus, for implementing sustainable development and planning in the starting point, there is a vital need to minimize the negative properties and maximize the positive properties of tourism [25]. Many studies suggest that to achieve a proper and sustainable tourism development, there is a need to understand the connection between the different components of the urban realm such as shared economic necessity and the population, the closeness of the home address or the residential area to the places with high visitors’ number [26], yet, the high number of the visitors leads to overcrowding in the destination place [27], which allows conflicts, alliances, paradox and contradictions to be identified through areas of interest and reference scales [28]. As a result, the urban tourism could provide a significant effect on the urban form, from one side it has a major effect on the urban economics, from the other side it has a significant role in connecting cities different parts, in another word it provides the “Flow” that represents the way that people permeate and flow between the different parts of cities, however, those flows are attached to the


central location in cities in term of the central places, which are the best location of the urban gentrification.

2.4. Tourism Gentrification

Tourism gentrification is an urban approach starting to appear within the last fifteen years [29], it first appeared in Gotham’s article on the Vieux Carré (French Quarter) in New Orleans [17]. The concept of the urban tourism is elated to different urban development approaches; accordingly, it is related to the role of local authorities, the growth in urban tourism, connection with property promotion, public urban regeneration, a residential displacement that include evacuating an area and changing the previous uses and settler with people that have more spending power and commercial gentrification [17].

The concept and approach of “tourism gentrification” as an experiential tool to explore and explain the alteration and transformation of a neighborhood of middle-class into a comparatively prosperous and high-class territory that incline to increase the propagation of commercial entertainment and tourism venues, this transformation leads to what some scholars call “chaotic concept” [11]. Scholars asserted that there are two types of tourism gentrification according to the nature of the development, the first approach is a twin process that combines the globalization and localization that outline contemporary urbanization and renovation processes, while the second approach provides a real challenge to the traditional understanding of tourism gentrification in terms of demand-side or production-side factors driving the process. However, some scholars see the process “as part and parcel of the class dynamics of urban transformation associated with capital investment and disinvestment” [30], or “highly visual expression of changing patterns of consumption in cities” [31].

The most significant part of the tourism gentrification is the concentration on the effect and impact that process gentrification in the destination place, accordingly the place itself with its physical characteristics has a great role on the urban development, so, all the physical characteristics, like the urban form and the urban layout will play a big role in the whole gentrification process, in addition to the generated effect on the community.

Hence, the plots price, residential displacement, the right to housing, loss of local traders, etc., will be a part of the tourism generation [32]. However, residential displacement is determined by tourism gentrification and revitalization policies which affect not just the neighborhood under gentrification, rather the effect would extend to several adjunct neighborhoods, particularly by the growing transformation of functions and uses [33].

2.5. Commercial Gentrification as Indirect Displacement

In the process of gentrification, there is a displacement

of old activities that would be replaced by new ones, numerous writers focused on Marcuse’s conceptualization that distinguishes between ‘indirect displacement’ and “direct displacement” [34], accordingly, ‘direct displacement’ refers to and denotes the transform and move the original inhabitants from the destination neighborhood, while, the other method is ‘indirect displacement’ which is a long-term approach and process that force the low -income people to move from districts or destinations’ neighborhood according to continuous pressure on them from the developers [35].

It is worth to mention that the commercial activities are the main force to transform area and make gentrification possible through the continuous pressure that influences the neighborhoods life and makes the alteration in the area structure, accordingly attracts more people to the area from one side and impacts the original people to leave the area gradually for wealthy people that can invest more in the area and looking for more silent and appropriate space. The gentrification literature identified the direct and indirect movements and displacement pressures, these forces, and pressures are well-defined below. A. Lack of consumption facilities: the main goal of this

approach relates to the incapability of low -income inhabitants to stay in their area as a result of the loss of stores and facilities, accordingly these people will be displaced by upper-income people gradually, it is worth to mention that the main force that plays the significant role in this process is the commercial gentrification [36].

B. Economic pressures: this one also depends on the commercial factors as the main force to transform the area in term of “affordability difficulties” [37], which means that neighborhoods are not able to provide affordable service within its boundaries, accordingly the inhabitant will start to leave such area because of the lack of the main affordable service and look for another place, as a result, new move of services and facilities start to move to the area and transform the main functions and uses.

C. Cultural pressures: this is related to the transformation of the land use according to the lifestyle’s characteristic, so there will be new forms of consumptions that work as generators to attract people to the new district [36].

D. The privatization of public space: This approach is related to transform the management of public space to private management and ownerships, accordingly, the public and communal area in the neighborhood could be privatized in term of the management by long term rent, thus it could be transformed to café and restaurant and entertainment area, however, this process will include the removal of the public facilities and benches [38] and dismissal of informal dealers [39]. These approaches of indirect displacement movements and pressures are not


working independently, but as mutual foundations that pressure the measurements of low-income inhabitants to continue in the neighborhood’s gentrifications [35].

2.6. Conclusion

Gentrification is the best way to increase cities productivities and enhance its social and economic values, however, the gentrified location must be located in the best central location in cities' urban layout. The central places serve cities in two ways, first, it links cities’ different components and ensures the flow between different parts, secondly, it increases cities comprehension through tourism gentrification as it clarifies in figure 1

Figure 1. Urban Development process through Gentrification

3. The Methodology The urban layout composed of five main parts, those

parts are the nodes (intersection), paths (street segment), buildings, boundaries, and agents, all those parts work together to create the urban built form [1], those parts are the most significant components that affect cities’ centralities layout parts [40]. Accordingly, any spatial network analysis for the urban layout should take into consideration the urban components to find a proper explanation for the urban reality and better understand the urban concentrated locations. As a result, the paper adopted Urban Network Analysis(UNA) to find reach and gravity’s centrality attributes to estimate the gentrified plots locations within the city, the method focuses on cities’ buildings, which accommodate activities, consequently where most urban activities and trips begin and end [41], as a result, the method takes into account the existing of the buildings as a third factor in creating cities graph network in addition to the edges and nodes of the street network, which flow between buildings.

The classic method of graph representations composed of nodes and edges only, ignoring the significant

importance of the variations that result from the inbuilt land-use distribution and density that formulate and characterize the environments and the urban layout [42]. However, the buildings’ locations which represent the positions of the most of the urban activities are missing in the classic representation of the urban layout analysis, accordingly one of the urban components is missing in the layout analysis, therefore, there is a need to add the missing part and represent the buildings in the analysis in addition to the network intersections that represent the street junction [41].

Although the buildings could be represented as nodes in the spatial analysis, the question remained whether there is an extra characteristic that should be added to the building nodes, although most urban graph representations to date have been used in the unweighted form [41], there is a need to add weights to the buildings in the spatial layout [1], as a result, the spatial network analysis should be represented through the participation of the four components those are the street segments (edge), street intersection (node), building (node), the boundary of the neighborhood ( the study area), taking in the consideration that the weights could be added to any of the above mentioned components, yet it could be added to the components’ characteristics, but we believe that the weight issue is far from the scope of this paper and that we used an unweighted network for the sake of the analysis of the current paper. For the sake of the paper, the authors used Esri ArcGIS v. 10.6 with urban network analysis plugins to commend all the analysis, an extra software of IBM SPSS v. 25 used for analyzing the research data and performing the required statistical analysis.

3.1. Reachability to the Urban Nodes

Reach plays a significant role in indicating the most accessible place in the urban fabric as it represents the places with the most accessibility area in the urban fabric, accordingly, the nodes reach centrality in a spatial graph designates the number of other nodes that are accessible and reachable from at the shortest path distance of at most, in our case will represent through two parts the first one is the buildings while the other part is the intersection or the junctions between the streets in the urban spatial layout. The mathematical equation of the reach centrality is defined in equation 1:

𝑅𝑒𝑎𝑐ℎ [𝑖] = ∑ 𝑊[𝑗].

𝑗∈𝐺−{𝑖},𝑑[𝑖,𝑗]≤𝑟 (1)

Where d[i,j] is the shortest distance of the path between nodes, the nodes represent the buildings’ location, W represents the proposed weight of destination nodes [41]. For the sake of this paper, we suggested declaring W=1 for all the nodes in the case study boundary area. Accordingly, all the nodes, more specifically all the building will share the same weights for the spatial layout analysis.


3.2. The Gravity of the Urban Nodes

Gravity centrality measures influences in the spatial impedance that required to travel to each of the destinations, first introduced by Hansen (1959), Gravity index is one of the most prevalent measures for the spatial accessibility in transportation research. Accordingly, the index represents high accessibility when the index is close to the high number of close to 1 in case of normalizing gravity, or averaging the index values as the mean maximum Gravity (MMG) for the block. However, due to the exponential distance decay, scholars found out that trips do not significantly contribute to the gravity index beyond a certain distance [43].

The Gravity centrality index adopts that accessibility at a location or a building is relative to the attractiveness (weight) of destinations surrounding and inversely proportional to the distances between them as it is clarified in equations 2 and 3 [41].

Gravity [i] = � 1𝑒𝛽.𝑑[𝑖,𝑗]

.

.𝑗∈𝐺−{𝑖},𝑑[𝑖,𝑗]≤𝑟

(2)

𝐺𝑟𝑎𝑣𝑖𝑡𝑦 [𝑖] = � 𝑊[𝑗]𝑒𝛽.𝑑[𝑖,𝑗]

.

.𝑗∈𝐺−{𝑖},𝑑[𝑖,𝑗]≤𝑟

(3)

The equation 2 and 3 are different in term of the weight of the node attractiveness which could be defined through the weight of the place, accordingly, if there is no weight attributed to the destination node then the general weight will be equal to 1, however, the gravity centrality index will exactly equal reach centrality index in case that the beta value in the equation was equal to zero, similarly, if the buildings are weighted, then the Gravity index is directly proportional to the weight of each of the other buildings that can be reached within the given search radius [41].

4. The Case Study of Erbil's Precinct The paper aims to find the best gentrification places in

the study area in the Erbil precinct, and the gentrified area should be located in the most appropriate central area in the urban spatial layout in term of reach and gravity centrality. The studied area is within the diameter called the 60-meter street in Erbil’s city, which is the area defined between the citadel in the center and the 60-meter street (Shasti), which is the boundary of the case study (Figure 2). The paper adopted the accessibility as a strategy to achieve the previous goals; accordingly, the central area will be the most appropriate location that provides optimum solutions.

The researcher studied the people's accessibility to each plot or building within the studied area, accordingly, to find reach and gravity's centrality values. After defining the boundary which is one of the urban components, the papers used the other three components of the urban layout by converting them to path and nodes that interact together in

the urban spatial analysis.

Figure 2. The studied area, the yellow line defines the boundaries of the reach and gravity calculation, while the blue lines defined the citadel precinct. Source: The Authors

The first part deal with the buildings in the spatial layout which is transformed to polygons that defined by the plots’ boundary and limits, hence, polygons define the boundary of each plot with the studied urban fabric, each polygon represents one building or plot connects to the path in the front of the plot, so, the path will have more connection when it gets to have more buildings or plots. The researchers proposed that each building has a direct effect on the total gravity of the layout, accordingly gravity power will increase according to the number of the buildings within the layout which means that the centrality values for the spatial layout increase rapidly the buildings increment.

Figure 3. The study area with building boundaries represented as polygons, a system of road networks as lines and the locations of the buildings as points


The second and third parts deal with the urban network which is the result of the nodes that represents that streets intersection and the path which is the distance between two nodes in the spatial layout. Consequently, the whole network represented by edges, so the edges of the paths represented by a fine network signify the whole accessibility networks of streets. Hence, it is clear that the research is looking for the physical urban characteristics that do change the working capability and ability of the urban layout to accept new challenges and uses in the urban

realm, accordingly to work properly with new uses that could be inserted as primary requirement of the urban touristic gentrification. The research methodology of defining nodes and the paths in the urban layout are clarified in figure 3.

The research used the reach and gravity equations for calculating the accessibility values for each plot in the site. The final output of the calculation is clarified in figure 4 and figure 5.

Figure 4. Reach of each plot with the graph of the studied area, the red color represents the powerful one while the green is the weak one. Also, the QQ plot clarify the distribution of the reach attribute through the city


Figure 5. Gravity of each plot with the graph of the studied area

As it is shown in figure 4, the maximum reach attribute is within the range (122-187) and the minimum is (0-9). Also, the results show that the distribution of the reach within the studied area is not normal as shown in the Q-Q plot, therefore, it is worth mention that the citadel precinct has a powerful reach attribute with a network that has implicit accessibility power (red plots). Similarly, the studied area has many plots with a highly reachable attribute, but unfortunately, most of those spaces and plots have been used as parking or garbage area within the precinct which needs to reconsider those locations and reuse those spaces with highly efficient new uses that serve the touristic gentrification strategy and process. The research used the reach values as an index for the weight attribute in the gravity model with a β value which is specified for pedestrian, as a result, the maximum gravity values is within the range (12999-22001) and the minimum is (0-404).

However, it is worth mentioning that the citadel precinct has a powerful reach value within the urban spatial network, but, that value is less important when it come close to the citadel itself, which means the centrality connection in term of reach is less important in those places. As a result, those spaces need to be reconsidered in term of spatial layout uses and distributions to avoid cutting off the network centrality connections. Also, the studied area has many plots with a highly reachable attribute, but unfortunately, most of those spaces and plots work as parking or garbage area within the precinct. The researchers used the reach values as an index for the weight attribute in the gravity model with a β specified for the pedestrian. The maximum Gravity attribute (figure 4) is within the range (12999-22001) and the minimum is (0-404). Also, the results show that the distribution of the Gravity within the studied area is not normal as it is shown in the Q-Q plot. According to the findings the citadel


precinct has many spaces with high gravity attributes, especially in the studied area. Unfortunately, most of the spaces with high gravity attribute in the studied area are used for parking, storage, and a place for collecting garbage.

It is worth mentioning that the gravity and reach attributes of the plots increases in the central area as it is clarified in figure 5. A large number of the spaces with

highly gravity attributes locate in the area within the citadel precinct; those plots have high connectivity properties with small size area comparing with the other parts of the city. Also, the research showed that the correlation between reach and gravity centrality values are significant with correlation coefficient 0.9 (Table 3) and coefficient of determination equal to 0.813 (Figure 6).

Table 3. Shows the correlation between the different attributes used in the analysis of the studied area

Figure 6. Radial distribution of gravity according to the radial distance


Most of the plots and buildings that have a powerful reach, gravity and correlation are located within the precinct area, which is the result of the dense buildings and incrementally successive small plots size, so that area is defined with high reach and gravity values which is essential for pedestrian, inhabitants, and visitors to be recognized the urban realm and build their mental image about the urban spatial layout.

The reachable plots and building play a significant role in the urban space configuration as studies on cognitive maps and urban travel found that people’s cognition is affected by urban configuration [44], therefore the research worked on the plots which have the most significant power in term of reach and gravity to be used in the gentrification policy for developing the area within the precinct area, to create a cognitive mapping [44].

Although some researchers insist that there is a strong correlation between the plot area and the accessibility, where the small plots are more accessible than the small one. The research showed that there is no significant correlation between the reach and shape area, according to the analysis there is no significant correlation between the reach the shape area which is just -0.015 correlation. There are two reasons for that result the first one is related to the reach mechanism and the second one related to the assessed nodes and locations which are considered all to have the same spatial weights. However, the analysis showed that the correlation between the gravity and reach area is significant at the 0.05 level, which is the result of the β value that adds excessive value to the gravity calculation because it is related to the people ability to surf the urban realm and understand the urban spatial layout.

5. Conclusions Giving to the literature, most of the developed methods

of the gentrification process depend on altering and changing the urban land use according to the requirement of the gentrification, however, the urban gentrification methods didn’t show how to do the change process, most significantly, how to select the gentrifications’ location? or where is the location of the gentrification nodes?

According to the finding, the studied area is full of plots and buildings with high reachability and gravity, places that have the initiatives to be best gentrified places, but most of the accessible spaces are abandoned or used as parking lots, at the same time, the land values in the area are too high which is not proportional to the current land use, and represents an economic failure in term of land use and efficiency. However, most of those spaces could be used in the gentrification process for developing the area. The researchers believe that those spaces with high degrees of gravity are the best places to locate new gentrified function in the studied area that could increase the connectivity of the urban layout as it is clarified in figure 7.

The analysis showed that the area around the citadel

which is supposed to have the most powerful ability in term of reach and gravity centrality doesn’t play a significant role in connecting the urban layout. The reason for that weakness lies in the fact that each plot within the ring around the citadel takes the power of the reach and gravity from one side while the other side is disconnected because of the existing of the citadel. Accordingly, there is no continuous connection because of the differentiation in the level.

6. Recommendations The research recommends adopting the spatial analysis,

especially the analysis based on the reach and the gravity to understand the best location or connection between the traditional places and its precinct, especially when there is the intention to develop that area for tourism engorgement. Also, there is a need to make more inventions in adding weights to the spatial nodes that connect the urban layout physical network because that weight might affect the spatial interaction between the connected nodes and as a result affect the whole urban layout.

Also, the research recommends studying the urban layout of the cities and finds a proper weighting system to measure the weights of the urban components in terms of the type, accordingly, there will be the weight that is specified for the edges, weight for the nodes, and weight for the boundaries. It is important to consider the differentiation between the weight of different types because the characteristics of the components differ in a wide range.

As well as, the research recommends reducing the traffic accessibility in the area with high reachability and gravity centrality index, as a result, the central area will be dedicated to the pedestrian rather than vehicles. The transformation of the area in this way will increase the walkability of the city, as a result, increase the connectivity of the different parts of the city which is a significant factor in creating a sustainable city.

Also, giving that the plot with highly gravity attribute should be allocated to the gentrification function, the process of gentrification should use some part within the citadel precinct to create an axis line between the precinct and the plots outside the precinct so the feeding of the area will continue smoothly and increase the accessibility of the site from the boundary of the 60-meter road.

Lastly, In the process of developing the studied area, there is a need to keep the number of gravities in its current rate or increase the number of buildings as this will increase the reach rate that proportionally increases the accessibility of the node in the studied urban fabric, for the development of such area which locates in the precinct, there will be a need to develop roots to increase the connectivity of the area with the other parts in the city, especially with new urban fabric as it is clarified in figure 7.


Figure 7. The development strategy in the precinct area built on plots of Gravity and accessibility




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The Cognition of the Architectural Styles Role on Thermal Performance in Houses of Semi-Arid Climates:

Analysis of Building Envelope Materials

Maryam Iranfar1, Salar Salah Muhy Al-Din 2,*

1Girne American University, University Drive, PO Box 5, 99428 Karmi Campus, Karaoglanoglu, Kyrenia, TRNC 2Independent Researcher, Kurdistan Region of Iraq, Iraq


Cite This Paper in the following Citation Styles (a): [1] Maryam Iranfar, Salar Salah Muhy Al-Din , "The Cognition of the Architectural Styles Role on Thermal Performance in Houses of Semi-Arid Climates: Analysis of Building Envelope Materials," Civil Engineering and Architecture, Vol. 8, No.5, pp. 929 - 941, 2020. DOI: 10.13189/cea.2020.080520.

(b): Maryam Iranfar, Salar Salah Muhy Al-Din (2020). The Cognition of the Architectural Styles Role on Thermal Performance in Houses of Semi-Arid Climates: Analysis of Building Envelope Materials. Civil Engineering and Architecture, 8(5), 929 - 941. DOI: 10.13189/cea.2020.080520.


Abstract The envelope of buildings has an important role in controlling the energy consumption in buildings. The climatic changes and depletion of conventional sources make this fact important. This paper endeavors to estimate the thermal performance (steady-state) condition of a range of houses envelope with different architectural styles in Northern Iraq. The study examines the potential of the building envelope materials to control heat loss/gain through calculating U-Value (Heat transfer coefficient value). The capacity of the building's envelope materials to maintain indoor temperature is a goal to perform thermal comfort and decrease energy usage. The potential of buildings envelope materials for each architectural style in terms of their thermal performance has been identified and the results have been determined. Reconcile the new materials and technologies with old vernacular materials and techniques, would grant effective design potential. Finally, the recommendations to develop new envelopes have been suggested to reduce energy consumption in future houses.

Keywords U-Value, Building Envelope, Semi-Arid Climate, Northern Iraq- Khanaqin

1. IntroductionBuildings consume about 40% of global energy, and

they emit approximately one third of carbon dioxide emission to the atmosphere [1]. About 50% of the energy the building needs is spent to achieve thermal comfort, therefore, heat exchange with the outer environment is pivotal in buildings [2]. Buildings' heat gain/loss could be different from building to another, depending on construction materials. In single-story buildings, heat exchange occurs through external walls and windows by 45%, while 42% of this exchange takes place through the roof and floor slab, whereas air leaks are responsible for 13%. In the multi-story building, 70% of heat exchange happens through outer windows and walls, and 13% through the basement slab and roof, while, 17% of exchange of heat with outside occurs through air leaks [3]. Thus, from previous data, we can understand that from 83% to 87% of the heating/cooling energy depends on the envelope of buildings. The reduction of energy consumption in the building sector considers the inexpensive way to mitigate CO2 emissions, when it is compared with other sectors [4].

930 The Cognition of the Architectural Styles Role on Thermal Performance in Houses of Semi-Arid Climates: Analysis of Building Envelope Materials

The study addresses the following questions; is there any relation between the development of architectural style and the U-value of their envelope in Kurdistan of Iraq? And how much the contemporary design in the buildings is aware of the thermo-physical properties in the envelope. The main objectives to answer previous questions are through; 1) identification of the main categories of envelope design according to the building style (vernacular, early modern, and contemporary); 2) studying thermo-physical properties for the envelopes in these styles of buildings. The methodology to approach the research is carried out by selecting a study region “town of Khanaqin” in the Kurdistan region of Iraq. The climatic characteristic of the Semi-Arid climate has been applied to the climatic zone for the study region depending on Köppen climate classification. Different types of houses’ envelope have been investigated in the study region. Heat transfer coefficient value for the building’s envelope is considered as the estimated tool to predict the energy consumption condition inside the buildings based on ‘Steady-state’ (the heat flow is no longer variable).

1.1. Building Envelope Properties

The building’s envelope is defined as a part of the building that physically separates the interior environment from the outside or exterior environment [5]. The building envelope includes four main elements; Fenestration (doors & windows), Roofs, Walls, and Floors (ground contact zones). In addition to these main elements, the envelope could contain thermal insulation; thermal mass; external shading devices, etc. [6]. To design buildings envelope many considerations should be involved. The envelope must be prepared to achieve structural function and meet the seismic condition, as well as aesthetic value [5]. The building envelope properties could affect thermal and acoustic comfort as it can attenuate surrounding environment noise [7]. Energy efficiency in the building can be enhanced by developing passive or active strategies for energy efficiency. Development of the physical characteristics of building’s envelope to maintain thermal comfort inside the building is classified under passive strategies while maintaining thermal comfort through artificial ventilation, air conditioning (HVAC) system, etc., known as active strategies.

1.2. Thermal Characteristics of Building Envelope

The energy balance in the building depends significantly on the design of the building envelope materials. Often, it is possible to reduce an active heating and cooling system usage, simply by changing the construction materials of the building envelope. Thermal characteristics of the envelope materials in buildings determine the rate of heat exchange [8]. The envelope materials in the building drive a significant role in thermal

comfort and energy consumption inside the building. The incidence of solar radiation on the envelope surface will be absorbed by the external surface of the building and flow through the envelope materials to reach the inner surface. Many factors are involved in the thermal performance of an envelope. According to CIBSE (Chartered Institution of Building Services Engineers), the (dynamic- state) thermo-physical assessment requires the calculation of four parameters: Surface Factor; Decrement Factor; Admittance value (Y-value); In addition to heat transfer coefficient value (U-value), which is used as a tool for (steady-state) thermo-physical assessment [9]. The study will focus on the (steady-state) condition, accordingly, the definition of (U-value) is mentioned in the next section with elucidation and elaboration, see section ‘1.4’. The Admittance value is defined as, the material potential to interchange heat with space for each degree difference in temperature that the temperature of space deviates from its average value. While ‘surface factor’ is the proportion of solar radiant heat flow re-radiated to the interior space to the heat flow incident upon the exterior surface. ‘Decrement Factor’ is the relationship between the inside and outside swing in daily temperature [10]. Hence, the thermal resistance of the envelope material affects the rate of heat transfer through that envelope. As much as a heat transfer coefficient value known by U-value is better, thermal performance will be better [11]. The building’s envelope plays a significant role in maintaining interior temperatures, consequently, it determines the energy required to maintain thermal comfort because of its position as a thermal barrier. Therefore, minimizing heat transfer through the buildings’ envelope is a pivotal part to reduce heating and cooling inside the building.

1.3. Insulation Materials' Places for Building Envelope

Two factors are very important in walls insulation, which are; location and thickness of the insulation. In hot climates, the insulation places on the exterior face of the building envelope (roof and exterior walls), so, the thermal mass of the envelope will not respond with the external environment and will maintain the indoor environment thermally. Using polystyrene insulation with ‘4’ centimeters on the outer walls and in the same time using vermiculite concrete on the top of roofs reduces the usage of energy inside the building by almost 15% [12]. In another hand, applying air cavities inside the exterior walls or in the roof ceiling will decrease the heating load inside the building significantly. The basic rule for pragmatic thermal mass is to determine the envelope insulation place within the building. One of the effective walls thermally is the masonry wall. It is functional during warm season and cold season too. In warm season it stores solar heat during the daytime and releases it to the out ambient at nighttime (when the outside temperature drops more than inside temperature). In cold seasons it absorbs


heat from interior sources and re-radiates the heat to the inside at night when the temperature falls [13]. Insulation of masonry walls from inside is, thermally makes the wall separated from internal direct and indirect heat gains by solar radiation through glazing, or indoor heating produced by an active system or occupants, etc., respectively. Thus, inner insulation on the wall’s mass is less active to maintain indoor thermal comfort during the warm season. Uninsulated masonry walls are thermally inactive, because they are introducing summer heat gains into the building, and letting internal heat to be released out in winter without good control of heat exchange through the envelope. Accordingly, in the cold season when the heating is demanded, the savings of heating load for the integral insulation (insulation within the wall) are better than the other types of insulation placing. However, in the cooling demand inside the building integral insulation had better function than placing the insulation on the interior face of the wall, and for lower cooling demand the outer insulation is the optimum [14].

1.4. U-value

‘U-value’ is known as the density of heat flux through a particular structure divided by the difference in ambient temperature on each side of the structural element in a steady-state case. Its unit is expressed by Watts per square meter per degree difference in temperature (W / m2 ° C) [15]. The steady-state heat flow through the material is called conduction. The R-Value (thermal resistance per unit area) is a prevalent technique used for assessing material thermal performance. This reflects heat flow resistance under "steady-state" conditions [10]. The primary stage is to define conductivity k (W / m K) of each material of the envelope, as shown in equation (1). This step should be taken depending on the tables published as BS EN 12664, and BS EN 12939, etc. Next stage is calculating the R (m2K / W) thermal resistance for growing material;

R= (t)/k (1)

Where; (t) is the envelope materials thickness for the building. The U-value is the inverse of R- value, as demonstrated in equation (2), where; the equation for single material is;

U= (1)/R (2)

And for multiple materials combining the envelop equation (3) applies:

U= (1)/ [(Ai+R1+R2+⋯Rx+Ae)] (3)

Where; Ai= the transfer resistance of heat on the inner surface

(m2K/W). Ae= the transfer resistance of heat on the outer surface

(m2K/W), [16]. As much as the U-value amount less means the material

thermal resistance to heat flow is higher when the amount

of U-value is less. Heat transfer is related to the difference between outside and inside temperature, solar radiation incidence on the envelope, and the total outer surface area of the building. Moreover, the envelope thermal potential depends on three factors, namely; thermal mass or the potential of heat storage; U-value; and their exterior finish material (light color reduces the absorption of solar heat and the opposite for dark color) [10]. Accordingly, U-value is one of the main factors to estimate the effective thermo-physical material for the envelopes in buildings, which allows the researchers to understand the thermal potential in the building. However, it is not the only factor to evaluate thermal performance of the envelope accurately under realistic conditions.

1.5. Turkish Standard (TS 825)

The thermal insulation drives a key role in reducing energy demands in buildings, which provide the advantages on many sides; environment, economics, and occupant’s thermal comfort. Turkey has achieved new Standards in 1998, called TS 825, which has been applied legally on the buildings after May 2000 [17]. U-values of several building elements in the various climatic regions of Turkey have been measured [18]. The estimated - value of the window, floor, roof, and walls of buildings in the four different climatic regions of Turkey are shown in table 1.

Table 1. Recommended (U values) for the four regions of Turkey (TS 825) Source: [18]

U wall (W/m²K)

U Roof (W/m²K)

U Floor (W/m²K)

U Window

(W/m²K)

Region 1 0.70 0.45 0.70 2.4

Region 2 0.60 0.40 0.60 2.4

Region 3 0.50 0.30 0.45 2.4

Region 4 0.40 0.25 0.40 2.4

This standard can be a good guideline for the evaluation of building envelope thermal potential in the neighboring countries, which have similar climatic characteristics, especially the countries which are not having such specific construction standards.

1.6. Semi-Arid Climates

A semi-arid climate or steppe climate according to Köppen climate classification is the climate of the territory that faces precipitation below the potential of “Evapotranspiration”, however, not extremely. It is the intermediates condition between desert climates (BW) and humid climates [19]. The Köppen climate codes Semi-Arid climate for cold semi-arid as (BSk), and warm semi-arid as (BSh), [20]. See figure 1.


Figure 1. Koppen-Geiger climates classification, shows Semi-Arid Climate zones [20]

To understand the difference between (BSh) and (BSk) there is Isotherm line delineates the border between them. This Isotherm is a line connecting points with the same temperature at a specific time or period. Commonly (BS) is characterized by a mean yearly temperature of 18°C, or an average temperature of 0°C or −3°C in the cold season. Any location temperature higher than this isotherm is classified as (BSh), and below the given isotherm is classified as (BSk). [19].

2. Methods The methodology in this research can be divided into

three main stages; First Stage: The review of literature, to identify key

information that could help in determining the thermo-physical properties for the building envelope and recognizing the benchmarks factors to assess the envelope thermal performance.

Second Stage: The quantitative method has been conducted in the methodology, through calculating U-value for different parts in buildings envelopes, based on the “steady-state” condition of heat flow through construction materials. Several residential buildings

(houses) envelopes with different ages and architectural styles have been investigated for this purpose. Houses with vernacular, early modern, and contemporary styles were observed in different places inside the town of ‘Khanaqin’. Houses have been selected for the evaluation because; the majority of the buildings in the town are houses. ‘Khanaqin’ as a part of the Northern region in Iraq has been chosen as a case study based on several considerations; 1) The Town is the hottest area in the Northern Iraq region in the summer, where reaches above 50° C in the summer. Khanaqin region climatic classification according to Koppen is characterized by Subtropical-Steppe climates (BSh); 2) ‘Khanaqin’ is an old city, therefore many styles of architecture, construction techniques, and different construction materials can be found inside the town. This gives the facility to investigate a different type of building envelopes throughout expanded history; 3) The city and the region of study (Kurdistan of Iraq), heavily using the electricity to maintain heating and cooling in the buildings, and the region suffering from a shortage of electricity supply. Hence, reducing the heat exchange through the envelope will participate in solving the electricity shortage problems. Buildings' thermal standards and codes in the region of study are not established. Turkey's location is


geographically close to the region of the study and some regions of Turkey's climatic conditions similar to the climate in the ‘Kurdistan of Iraq’. Thus, the estimated values of TS 825 standards especially the recommended U-values were considered for evaluating the best U-value for building envelope in this study. Turkish standard has divided Turkey into four climatic regions. One of the region's climatic characteristics is harmonized with the climatic characteristic of the study area, which is ‘Region 4’ that is described in table (2) because it is considered inner- land and not coastal area [18].

Table 2. Monthly average external temperature values (oC) for using it in calculations of heat loss and condensation for the different regions, [18].

Month Region one

Region two

Region three

Region four

Jan. 8.4 2.9 -0.3 -5.4

Feb. 9.0 4.4 0.1 -4.7

Mar. 11.6 7.3 4.1 0.3

Apr. 15.8 12.8 10.1 7.9

May 21.2 18.0 14.4 12.8

Jun. 26.3 22.5 18.5 17.3

Jul. 28.7 24.9 21.7 21.4

Aug. 27.6 24.3 21.2 21.1

Sept. 23.5 19.9 17.2 16.5

Oct. 18.5 14.1 11.6 10.3

Nov. 13.0 8.5 5.6 3.1

Dec. 9.3 3.8 1.3 -2.8

Third stage: the finding evaluation for the different U-value of envelope elements (external walls, roofs, floors, and windows) in the different architectural style of buildings was carried out. The results showed that the envelopes thermo-physical properties in each type of the buildings progressively from old types to the contemporary ones.

2.1. The Study Area

Figure 2. Kanaqin location within Kurdistan region and Iraq [22]

‘Khanaqin’ is located in north-eastern Iraq and southeast of Kurdistan. It is Adjacent by Iran from the east, and Halabja district from the north, Kalar district is located on the west side, while the rest of Iraq is located in the south, as shown in figure 2. The total area of the ‘Khanaqin’ is around 3915 square km, and the area of the town only is 1288 square km. The total population in this town is estimated by 175,000 people, and its elevation is 183 meters above mean sea level [21].

‘Khanaqin’ is one of the most important areas that contain a lot of important minerals as well as oil. In the town the first oil refinery was found in 1926 and was named ‘Alwand Refinery’ on the name of the river which divides the town into west and east banks [23].

2.1.1. The Case Study Climate context Study region is a part of Northern Iraq’s region which is

characterized according to the ‘Koppen’ climatic classification by semi-arid climate, mountainous (high-land) region, and cold in winter, and dry in summer. Generally, the area influenced by the Mediterranean climate, so its precipitation takes place in spring and winter. The higher average temperature in a month is 33.30 °C in July and the lower average monthly temperature is 5.7 °C in January. The average annual relative humidity is 56.5 %, [24]. The maximum daily temperature may reach as high as 50 °C in hot summer periods, while the minimum daily temperature can drop to under zero in cold winters [25].

2.2. Observation of Sites

Field observations were carried out for different types of houses styles (fig. 3) from several historical periods in three selected sectors of the town of Khanaqin. Selected sectors consider the oldest sector’ Hamidia” (going back to end of nineteenth century), and mid-age sector 1930’s to 1960’s ‘Mazra’a’, and contemporary sector ‘Mamostayan’.

2.2.1. Vernacular Houses in the Old Sector “Hamidia”

The buildings in this sector are majority residential, with few commercial buildings ‘shops. A maximum number of floors in this sector are two stories, most of them were built at the end of the 19th century or very beginning of the twentieth century, and the buildings were almost abandoned because of their dilapidating condition. In vernacular building’s thick outer walls (around one meter) had been observed, and the timbers had been used in the roofs to support the thick soil layer above the straw mat. See figure 4.


Figure 3. Architectural style in Khanaqin, (a) Vernacular house, (b) early modern house, (c) Contemporary house (By Author)


Figure 4. (a) Exterior walls of Vernacular buildings. (b) The roof in vernacular buildings. (By Author).

U-values were calculated for the entire parts of the envelope (Exterior Walls, Roofs, Floors, and Windows) to evaluate the thermal potential of the envelope for these buildings’ types through U-value.

The standard conductivity for each single material has been taken from TS 825’s tables. A site visit has been carried out to measure the thickness of the materials for each part to divide that thickness on the conductivity to obtain the resistance. The mathematical calculation for the U- value demonstrated the results of 0.454, which is considered a relatively good heat coefficient value compared with TS 825’s Standards of Turkey. Moreover, the U-value for the roof has been calculated and evaluated in these vernacular buildings, and the results showed not climatic responsive U-value based on TS 825’s Standards of Turkey, where the heat coefficient value was 1.14

(W/m2K). The floors in these buildings consist of three main layers which are imported suitable compacted embankment or stone chips (Sand, gravel, crushed stone), and a layer of gypsum mortar has been placed on it, then covered by flat burnt- bricks known locally by ‘Farshi’. U-value for the floor has been evaluated in these buildings based on the construction layers, and it was found equal to 1.515 (W/m2K), and that indicates a relatively weak U- value in the roof for this climate in these styles of buildings. The windows of the vernacular buildings encompassed single glazing and wooden frame. Accordingly, the windows U- value in the vernacular house was found based on TS 825’s. The result referred to very weak climatic responsive U- Value for the windows, where found 5.1 (W/m2K). See table 3.


Table 3. U- values for the external walls,Roof,floor material and window type in the vernacular buildings

Exterior Walls Building material

No. Types of material (t)Thickness of the material (m)

(k)Thermal conductivity

(W/mK)*

(R) Thermal resistance (m²K/W).

See Eq. (1)

U- Value for the whole wall (W/m2K). See Eq. (3)

1 Flat Brick-burnt (Farshi) 0.25 0.81 0.309 U wall=1/ (Ai

+1/R1+1/R2+1/R3+Ae)** U wall=1/(0.13+

0.309+1.625+0.098+0.04)= 0.454

2 Adobe 0.65 0.40 1.625

3 Gyps plastering (with aggregate) 0.05 0.51 0.098

Roof Building material U- Value for the whole roof (W/m2K). See Eq. (3)

1 Straw 0.02 0.058 0.345 U roof=1/ (Ai +1/R1+1/R2+1/R3+Ae)**

URoof=1/(0.13+0.345+0.125+0.233+0.04)= 1.14

2 Plywood 0.025 0.20 0.125

3 Clay 0.35 1.500 0.233

Floor Building material U- Value for the whole floor (W/m2K). See Eq. (3)

1 (stone chips) 0.25 0.700 0.357 U Floor=1/ (Ai

+1/R1+1/R2+1/R3+Ae)** Ufloor=1/(0.17+0.357+0.071+0.0

62+ 0)= 1.515

2 Gypsum mortar,

lime-based gypsum mortar

0.05 0.70 0.071

3 Burnt Brick ‘Farshi’ 0.05 0.81 0.062

Window type U- Value for the window (W/m2K).*

1 Wooden processing window with single glass 5.1

*From the TS 825’s tables, pages (35-51) **Ai, Ae are internal and external surface thermal transmission (convection) resistance values for external walls= 0.13 and 0.04 (W/m2K), respectively, from TS 825.

Table 4. U- values for the envelope in the traditional or early modern buildings

Exterior Walls Building material

No. Types of material (t)Thickness of the material (m)

(k)Thermal conductivity (W/mK) *

(R) Thermal resistance

(m²K/W). See Eq. (1)


1 Gypsum Plaster 0.03 0.70 0.043 U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae) **

U wall=1/(0.13+ 0.043+0.444+0.016+0.04)= 1.485

2 Burnt Brick 0.36 0.81 0.444

3 Cement mortar plaster 0.025 1.60 0.016

Roof Building material U- Value for the whole roof (W/m2K). See Eq. (3)

1 Gypsum Plaster 0.015 0.70 0.021 U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae) ** URoof=1/(0.13+0.021+0.148+0.133+0.04)=

2.12 2 Burnt Brick 0.12 0.81 0.148

3 Clay (Soil) 0.20 1.500 0.133


1 (stone chips) 0.20 0.700 0.286

U Floor=1/ (Ai +1/R1+1/R2+1/R3+Ae) ** Ufloor=1/(0.17+0.286+0.048+0.021+0.019+

0.0)= 1.838

2 Plain Concrete 0.08 1.650 0.048

3 Cement mortar Screed 0.04 1.400 0.021

4 Mosaic tiles 0.025 1.300 0.019

Window type U- Value for the window (W/m2K). *

1 Aluminum Processing with single glass 5.9


2.2.2. Residential Sectors in “Mazra’a” The majority of these buildings are holding an early

modern style. The exterior walls, commonly, constructed with 36 cm thick burnt bricks as masonry units and plastered by cement mortar from exterior face, while plastered white gyps from the interior face. The U-value for the exterior wall has been evaluated in the early modern buildings and found equal to 1.485 (W/m2K), which showed that it is not meeting the climatic requirement in the region. The roofs in these buildings have been constructed by interlocking burnt bricks with the help of ‘I beam’ far one meter from each other. The roofs in these buildings are still using the vernacular system in putting a layer of thick soil on the roof of the building. U-value for the roof has been calculated in the early modern buildings, and the results have shown that the U- Value is 2.12 (W/m2K). This number shows a poor thermal resistance in front of the climatic needs in this area, according to TS 825’s Standards of Turkey. The floor in these types of buildings had been built by Mosaic tiles fixed on the mortar screed cement layer above a layer of plain concrete upon the layer of stone chips. Therefore, the floor U-value was evaluated in early modern buildings, and the result was weak to respond to the climatic requirement and found equal to 1.838 (W/m2K). The windows generally in traditional buildings as well as early modern ones in ‘Khanaqin’ had been manufactured by the single glass (un-coated) and wooden frame protected from outside by banditry iron bars. The U- Value of the windows in these houses was found not responding to the climatic requirement as the same situation in vernacular buildings, where the U-value was 5.9 (W/m2K). See table ‘4’.

2.2.3. Contemporary Sector in “Mamostayan”

The majority of the houses is contemporary and built in the 21st century after 2003, constructed with new construction material and new design style. The contemporary houses either build-up by burnt bricks or concrete blocks and exterior walls are covered by stone. To calculate U-value for the exterior walls at contemporary houses, a concrete block has been involved

and second time burnt bricks have been applied and found equal to 2.237 (W/m2K) and 1.901 (W/m2K), respectively, as shown in table 5. Both types of walls demonstrated the worst U- Value compared with previous architectural styles. The roofs of contemporary buildings generally consist of reinforced concrete slab, plastered by gypsum from inside the building and covered from outside either by bituminous insulation membrane known ‘ISOGAM’ (0,01 mm aluminum foil bituminous pulp) or covered by a layer of concrete tiles Known (Shtygar). ‘Shtygar’ tile is setting on a layer of sand and high-density styrofoam between the concrete slab and the concrete tiles. However, the latter type of roof does not prevail in contemporary buildings in Khanaqin and the reason behind that is the cost of this type because it needs more material and costs more time. See figure 5.

Accordingly, the U-value for the roof has been evaluated in the contemporary buildings for both types of materials and was found equal to 2.92 (W/m2K) for the first type, which is not meeting the climatic requirements based on TS 825’s Standards of Turkey. The U-Value for the second type of roofs was 0.462 (W/m2K), which was found successfully responding to the climatic requirements as per TS 825’s Standards of Turkey. Also, the result demonstrates that the polystyrene materials that used in the roofs demonstrate an effective solution to improve U-value for the roofs. Regarding the floor materials which are usually used in contemporary buildings is granite or marble on the layer of screed cement mortar spread on a layer of plain concrete upon layer of crush stone. Thus, the floors U-value evaluation in the contemporary buildings, the result showed 2.584 (W/m2K), which considers the worse U-Value in all the tested buildings. In contemporary buildings, windows have two types either plastic with double glass which the U-value was found 2.9 (W/m2K), or Plastic with single glass which was found 3.4 (W/m2K). Therefore, U-value evaluation for the windows in the contemporary buildings, according to TS 825’s tables, demonstrates the two main types of windows are not adequate to overcome the climatic characteristic in this region. See table 5.


Table 5. The U- values for the envelope elements in contemporary buildings (Developed by Author)

Exterior Walls Building material (Type 1)

No. Types of material (t)Thickness

of the material (m)

(k)Thermal conductivity

(W/mK)*

(R) Thermal resistance (m²K/W).

See Eq. (1)


1 Gypsum Plaster 0.03 0.70 0.043 U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae)**

U wall=1/(0.13+ 0.043+0.217+0.017+0.04)= 2.237

2 Concrete block wall 0.20 0.92 0.217

3 Sedimentary stone 0.04 2.30 0.017

Exterior Walls Building material (Type 2)


1 Gypsum Plaster 0.03 0.70 0.043 U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae)**

U wall=1/(0.13+ 0.043+0.296+0.017+0.04)= 1.901

2 Burnt Brick 0.24 0.81 0.296

3 Sedimentary stone 0.04 2.30 0.017

Roof Building material (Type 1)

U- Value for the whole roof (W/m2K). See Eq. (3)

1 Gypsum Plaster 0.01 0.70 0.014 U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae)** URoof=1/(0.13+0.014+0.08+0.079+0.04)

= 2.92 2 Reinforced Concrete 0.20 2.500 0.080

3 (ISOGAM) 0.015 0.19 0.079

Roof Building material (Type 2)

U- Value for the whole roof (W/m2K). See Eq. (3)

1 Gypsum Plaster 0.01 0.70 0.014

U wall=1/ (Ai +1/R1+1/R2+1/R3+Ae)** URoof=1/(0.13+0.014+0.08+0.079+

0.043+ 1.666+ 0.086+ 0.024+0.04)= 0.462

2 Reinforced Concrete 0.20 2.500 0.080

3 (ISOGAM) 0.015 0.19 0.079

4 Sand 0.03 0.70 0.043

5 Styrofoam 0.05 0.03 1.666

6 Sand 0.06 0.70 0.086

7 Concrete tiles ‘Shtygar’ 0.04 1.650 0.024


1 (stone chips) 0.10 0.700 0.143 U Floor=1/ (Ai

+1/R1+1/R2+1/R3+Ae)** Ufloor=1/(0.17+0.143+0.048+0.021+0.00

5+0)= 2.584

2 Plain Concrete 0.08 1.650 0.048

3 Cement mortar Screed 0.03 1.400 0.021

4 Granite 0.015 2.800 0.005

Window types U- Value for the window (W/m2K). *

1 Plastic processing with double glass 6mm (un-coated) 3.4

2 Plastic processing with double glass 6mm (E-low, coated) 2.9

Table 6. Comparing the standards with the existing U-value in the houses at Khanaqin

No. Items U wall U Roof U Floor U Window

1 TS 825 Standard for (Region 4) 0.40 0.25 0.40 2.4

2 Vernacular houses 0.45 1.14 1.52 5.1

3 Early modern type houses 1.49 2.12 1.84 5.9

4 Contemporary houses 2.24/1.90 2.92/0.46 2.58 3.4/ 2.9


Figure 5. Shtygar for building roofs in contemporary houses in Khanaqin (By Auther)

3. Discussion Conventional envelope in three houses with different

architectural style in ‘Khanaqin’ was evaluated thermo-physically from different places inside the town through assessment of U-value for the whole envelope. The result had been compared with the Turkish standard TS 825. See table ‘6’.

The results demonstrate that the houses in different periods with several building styles didn’t meet the requirement of the climate in this region based on the standards of TS 825. The findings have shown U- value of the outer walls of vernacular houses is only the one that is closed to the standards and registered 0.45 (W/m2 K). This returns to the role of ‘Adobe’ utilized in the outer walls, which made a significant improvement in the U- Value. Other building styles with more new construction materials didn’t reach the requirement. For example, the exterior walls for the building of the early modern style which are newer than vernacular buildings style in the town by 30 to 50 years had U-value 1.49 (W/m2 K). The contemporary architectural style, which started to be constructed in the town at the beginning of the twenty-first century, had worse U-value for exterior walls of the buildings, which registered 2.24 and 1.90 (W/m2 K). The U-value for the roof materials showed that neither vernacular buildings nor the early modern houses met the standards. However, in the contemporary style roofs, two types of U-value have been gained, one of them was very far from the standards, and the other met the required U-value. The reason behind that was the use of polystyrene foam as insulation material, which makes a big improvement in the U-value of the roof, where U- value for the roof was 2.92 and because of the insulation material dropped to 0.46. In the case of windows, the application of new material in windows demonstrates improvement in U-values progressively, with the help of contemporary materials. The vernacular buildings registered very poor U-value in the window which was 5.1 (W/m2 K). In the early modern styles of buildings, the

U-value registered 5.9 (W/m2 K) because of the usage of the Aluminum (metal) window system. However, because of applying the double glazing, and adding ‘E-low’ material in the styles of the contemporary building, the U-value reached 3.4 and 2.9 (W/m2 K), respectively. However, it couldn’t meet the requirement as per the standard which is 2.4 (W/m2 K) for the windows responding to the similar climatic character of ‘Khanaqin’ which is located in the hot region in Kurdistan of Iraq called ‘Garmian’ (means the warm region in the local language). As per the ST 825 standards tables, to reach the appropriate U- value, the E-Low coated glass and 9mm thick double glass are required. Moreover, in case the aluminum proceeding used then aluminum with an insulation bridge is recommended [18].Thus, the study demonstrates that vernacular buildings meet the required heat transfer coefficient value (U-value), partially and not in all the envelope elements (only the exterior walls) getting advantages from 'Adobe' as a building unit. Also, the new buildings with newly designed materials almost didn’t meet the U- value requirements unless applying the insulation materials such as polystyrene foam, which showed a very effective design role, when applied in the roofs. The windows had been showing that through new materials in the glazing system the U-value could be improved progressively.

4. Conclusions Based on the TS 825 Turkish Standards, several

materials U-values were applied to be calculated and compared in the different architectural styles of houses in 'Khanaqin'. Three different styles in architecture have been involved to be tested, from different ages of the city of ‘Khanaqin’. First is the vernacular architecture style, the second style was the early modern architectural style, and the third style was the contemporary architecture style. The study focused on houses as the most prevailed type of buildings in the region of study. The results demonstrated


that the construction materials were used and are still used in the different architectural styles of houses envelope are not well designed to meet the requirement of the local climate, where the U-value of the envelope materials in different architectural styles and periods showed a weakness compared with the standards to be adaptive to climate needs. However, some particular materials in vernacular architecture such as ‘Adobe’ in the external walls demonstrated an effective role in controlling heat loss/gain. In the same context, polystyrene foam which was applied in the roofs at contemporary houses has shown the effective potential to dominate the heat reciprocation between indoor and outdoor. Moreover, contemporary materials in the windows with new technologies demonstrated good ability in this context too. The assessment implemented based on calculating (U- Value) in the (steady-state) condition of building envelope materials. The use of energy in new buildings needs more energy than the old buildings due to the weak U-value of construction materials because designers now rely on the use of active systems to achieve thermal comfort, and they neglected the passive design which reduces energy use.

According to the findings in this study, the author reached several recommendations to develop the existing and future building envelopes, which are; 1. Introduction of the insulation material such as

polystyrene foam to improve the U- value in the envelope, especially for floors and roofs is recommended for reducing energy demands in the building, through improving thermal performance. But the placing of these insulation materials should be identified based on a climatic characteristic, as explained in point number ‘5’, bellow.

2. To take the wisdom from the thermal properties of some vernacular materials like 'Adobe' to re-design the contemporary exterior walls are recommended.

3. To effectively respond to the climatic needs in the study area, it is recommended to use double glazing and e-low in the windows, provided that the thickness of the glass is 9 mm or more, to achieve the required U-value, which meets the climatic requirements. If the aluminum proceeding windows are applied, then the ‘Insulation Bridge’ is recommended too.

4. Avoiding ‘hollow concrete blocks’ as a masonry unit without applying additional insulation materials, because of the low thermal potential of this masonry unit for responding to the regional climatic characteristics.

5. According to the theoretical analysis and literature review, the insulation material that would be added to the exterior envelope is the best for controlling heat exchange in the study area climate during the summer. However, the integral insulation is good for controlling and distributing the heat gain in summer and winter. Accordingly, integral insulation is recommended in the region of the study.

6. It is very important to start thinking seriously to establish local standards for the Kurdistan region of Iraq, to encompass the own environmental and regional characteristics. In this case, a more realistic evaluation of the building's thermal performance can be obtained.




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An Experimental Approach to the Sophomore Architectural Design Studio

Milorad Pavlovic

Faculty of Architecture, Alanya Hamdullah Emin Pasa University, Alanya, 07400, Turkey

Received August 20, 2020; Revised September 14, 2020; Accepted September 21, 2020

Cite This Paper in the following Citation Styles (a): [1] Milorad Pavlovic , "An Experimental Approach to the Sophomore Architectural Design Studio," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 942 - 949, 2020. DOI: 10.13189/cea.2020.080521.

(b): Milorad Pavlovic (2020). An Experimental Approach to the Sophomore Architectural Design Studio. Civil Engineering and Architecture, 8(5), 942 - 949. DOI: 10.13189/cea.2020.080521.


Abstract Architectural education is widely dominated by design studio courses. Their organization and development constitute an open challenge for educators due to the complexity of the participating factors, i.e., teaching method, design topics, assignments, expected learning outcomes, and experimentation. In particular, the organization might be considered as the factor that characterizes the whole process of the design studio course in different forms. In this research, an experimental approach based on 3 project assignments has been proposed for the sophomore design studio courses, as an alternative to the common practice of single project assignment per semester. The procedure aims on proposing a method that allows the students to maintain the organizational schemes of the freshman courses and increase their competences constantly and progressively. The process has been implemented during the fall semester 2019 and applied in the Architectural Design Studio 1 at Alanya Hamdullah Emin Pasa University, Department of Architecture, program in the English language. At the conclusion of the experiment, a questionnaire for the students has been conducted. The paper presents the organizational model proposed, the results of the questionnaire, observations of the lecturer, and discusses the reliability of the proposed method.

Keywords Architecture, Architectural Design, Architectural Education, Architectural Studio, Experimental Model

1. Introduction

1.1. Historical Background

It’s well known that the Design Studio course plays a primary role in architectural education. Due to its character of learning-by-doing and the highest number of credits that usually deserve, this course commits most hours of the students' weekly workload. Another peculiar characteristic of the design studio course is being flanked by the supportive courses. Such courses, mainly with theoretic character, provide students specific knowledge on single subjects (such as history and theory, technology and materials, structural principles, etc.) whereas in the design studio courses the knowledge acquired from different disciplines should come together across the design studio problem. This heterogeneous character of the Design Studio course is also at the base of its complex social and cultural aspects [1, 2]. Nevertheless, the role played by the critiques and the juries should be omitted as a fundamental part of architectural education [3, 4].

Historically, the character of learning-by-doing was particularly enhanced since the central core of architectural education was the master-apprentice relation based on the atelier’s environment [5]. The center of education remained at the atelier also at the beginning of the 20th century, with Bauhaus institution [6], however, it has been only in the years 1980’s that present day’s model of studio-based design instruction has been defined [7, 8]. Such model, adopted for decades, became the emblem of architectural education, widely adopted. Among the researchers developed in further years, that focused on its


adaptation, can be highlighted the proposal of defining an educational program based on 2 contemporary studios [9] and the role of CAD applications [10].

1.2. Present Day's Educational Problems

From a review of the technical-scientific literature, it may be assumed that, at present days, there is no consensus agreed upon the methodological and pedagogical approaches to be practiced in an architectural design studio course. The organizational problem remains among the open debates [11-13], as well as the option of approaches involving the creative, critical and pragmatic thinking [14-16], the communication techniques [10], the value of sketches and hand drawings [17-18], and the grading issues [19-20].

Accordingly to this review, can be observed the need of providing models that can improve the existing approaches. In particular, the new paradigm proposed by Wang [14] seeks to provide the rigor that is lacking in design education. On the other hand, the model proposed by Ciravoğlu [13], proposes a solution to overcome the master-apprentice condition, whereas the research proposed by Pasin [21] discusses the central role of the design studio in contemporary teaching methods. Similarly, in the author’s opinion, proposals for organizational models are worth of recommendations, not only for a single course but also for the teaching and methodological continuity in between courses. In particular, this research intends to propose an organizational model that considers the general aspects of the freshmen studio courses and suggests a continuity for the sophomore level.

1.3. Problems Examined in the Context of the Research

Observing the participating factors involved in a design studio course (Figure 1), the present research intends to focus on the problems of course organization, design topic, and assignments. One of the reasons is that, for such matters, the available literature is limited and the choice of the topics is mostly related to the lecturer’s choice or based on the own experiences [22, 23]. Another reason derives from the observations on the existing practices of studio course management, and prerequisite relations. As in many programs design studio courses are following the prerequisite requirements, reasons for which students need to complete the courses progressively, however not always this progress corresponds to continuity in terms of pedagogy and methodology. Often for the students starting a new design studio course mean developing different working methods and different approaches. Therefore, the common feeling is of starting every time from zero, with limited possibilities of transmitting the knowledge acquired previously to the next levels.

As still there’s no unanimous consensus about design topics to be proposed at each level, the residential topic is often considered the less complex and frequently assigned

to the novice students. Hence, the solution of a residential problem has been considered as a tool for design, with particular attention on providing the students’ abilities and knowledge for solving the proportions and relations of the interior and exterior designed spaces. Relations, those students generally examine during the freshmen year [24]. Thus, the research addresses a method for sophomore students, which allows them to maintain the general organization of the Basic Design courses as well as the notions acquired in the course of Introduction to Architectural Design. Additionally, the model intends to propose new elements, such as building typologies, construction materials, and contemporary structural systems.

Figure 1. Contextualization of the research

Therefore, in the present research, an organizational model for the sophomore studio course has been proposed that considers: i) a 15 weeks semester; ii) 3 project assignments; iii) Basic Design and Introduction to Architectural Design Courses completed during the freshman year. The model aims on overcoming the consolidated practice of assigning one project per semester and allowing students to: i) acquire the knowledge by practicing gradually and additionally; ii) to manage the time properly; iii) to perform research work as a form of self-critiques activity. The course model has been applied during the fall semester 2019 in the Architectural Design Studio 1 at Alanya Hamdullah Emin Pasa University, Department of Architecture, program in the English language.

2. Materials and Methods Starting from the considerations mentioned above, an

experimental approach to the sophomore design studio course has been developed. The model considers a 15

944 Civil Engineering and Architecture 8(5): 942-949, 2020

weeks semester, 3 projects development, 3 juries, and enhances activities such as lectures and different forms of critiques (collective and individual). In particular, the choice of assigning 3 design solutions derives from the observation of the previous experiences. It has been noticed that with the common practice of assigning 1 project per semester, generally, students exhibit a disconnected trend regarding the course participation, as well as dedication on a project solution. One of the reasons, in the author’s opinion, might be attributed to the long period that occurs between the conceptual sketches and final presentation. Therefore, a model for the studio organizations has been proposed with the aim of providing students more stimuli and possibilities to examine a completed project in a relatively short time (5 weeks).

2.1. Organizational Model

The course has been organized accordingly to a schedule of 15 weeks divided into 3 steps of 5 weeks each. Each step consisted of 4 lecture-critiques weeks and 1 jury week. For each step, a different topic has been defined: 1st step development of the patio house typology; 2nd step development of the row house typology; 3rd step development of the villa typology. The sequence of the topics has been proposed to increase, step by step, the complexity level of the designed environments, and their relations.

Since a patio house (or a courtyard house) can be considered an intrinsic residential unit, with patio as the focal point for all the activities, the attention during the critiques has been mainly oriented toward 3 points: i) human scale; ii) in plan design relations between the main spaces and service spaces; iii) visual relations between each patio and related interior areas. Further considerations involved the usage of auxiliary devices, aimed at improving the privacy of the occupants or the extensions of the activities among the open, semi-open, and closed spaces.

As the next step, with the row house typology, the 3rd dimension and the vertical relations have been enhanced in the progress of development. Here, additionally to the previously examined topics, the role of the staircase, as an element for both service function and space organization, has been considered. Differently from the previous study case, the students were invited to consider the design of the elevations, rather than simply extrude them from plans, introducing the concepts of shading and the usage of materials.

Successively, with the villa typology, the problem of solving a residential unit has been shifted, from the planimetric to the volumetric approach. Here the students were invited to invert the design trend (plans, sections, elevations, 3D models), starting from the volumetric approach, passing through the sections and elevations design, and verifying the functions through plan design. Differently from the previously designed typologies, the problem of the functions solutions has been significantly extended, considering the design of the exterior spaces as: i) extensions of the living area; ii) additional utilitarian spaces; iii) environments designed for leisure activities.

As one of the essential components of design education is represented by the critiques, during the studio course the students’ progress has been checked both collectively and individually. Initially, the critiques were done as a table discussion, involving 8-10 students at the time. The process is intent to highlight the common mistakes both in terms of design solutions and graphical representation. Successively, the critiques were held in the 1 to 1 manner, in order to focus on each project and examine the own potential. Since the course was given once a week with a schedule of 8 hours and a ratio lecturer/students of 1/15, most of the time it was possible to check the students’ progress twice per day. Besides the critiques, theoretical lectures were performed to focus the attention on specific questions that emerged during the project developments. In particular, the lectures focused on: i) model-making techniques; ii) advanced graphical representation and, iii) study case critical analyses.

To evaluate the progress and the overall performance of the students, 2 intermediate juries and a final one have been defined. For both the intermediate juries, students were requested to present besides their project solutions, a research work consisting of critical analyses of architectural examples related to the topic. Hence, theoretical research was integrated into the design process. For the final jury, besides the development of the villa project and the relative research work, the students were requested to improve the previously designed typologies accordingly to the critiques received during the juries. Therefore the design process for each typology continued till the end of the course, highlighting the progress achieved during the course. Figure 2 summarizes the proposed model. The abbreviations are reassumed as follows: w = week; L = lecture; cc = collective critiques; ic = individual critiques; J1, J2 = intermediate juries; FJ = final jury.


Figure 2. Course organization summary

3. Results At the conclusion of the experiment, with the aim of

verifying the proposed model, a questionnaire has been prepared and submitted to 30 students who attended the course. Considering that the course was the first studio experience for most of the students (after the freshmen courses), it was particularly important to understand also how the lectures and the knowledge have been transmitted.

As well known, questionnaires can be considered as valid collection tools for quantitative researchers [25]. Their reliability and efficiency is widely discussed in technical/scientific literature and several models can be applied for the analyses in higher education [26-28]. In particular, for the present research the methods that involve College Student Experiences Questionnaire [29] and the Course Perception Questionnaire [30] have been considered. Hence, a questionnaire has been arranged including 3 sets of questions. For each question, a scale from 1 to 5 has been to order to express the level of agreement.

The 1st set of questions aimed at the evaluation of the course objectives, time organization, and the students’ contribution. The 2nd set of questions indented to examine the efficiency of the learning environment, teaching methods, and learning resources. Lastly, the 3rd set of questions aimed at the evaluation of the quality of delivery and gave the possibility to the students to suggest the improvement and criticize the features.

Accordingly, to the answers of the students, the absolute majority agreed that the course objectives were clear (Figure 3, A1), that the course workload was manageable (Figure 3, A2) and that class time was well organized (Figure 3, A3). Still, nearly the totality of the students

agreed on the fact that they participate actively in the course (Figure 4, B1) and that they made progress (Figure 4, B2).

The 2nd set of questions aimed at the examination of the learning environment and learning resources. Here, a low percentage of the students disagreed with the proposed model in terms of achieving the learning outcomes (Figure 5, C1) and with the fact that the overall environment was conducive to learning (Figure 5, C3). However, none of the students argued that the teaching methods didn’t encourage participation (Figure 5, C2).

More differentiated answers of the students have been collected throughout the answers on the questions related to the learning resources adopted. Here the majority of the students agreed on preferring internet as the main source of the materials (Figure 6, D4), rather than the course materials (Figure 6, D1), suggested textbooks (Figure 6, D2) and the hard-copy library sources (Figure 6, D3).

The 3rd set of questions aimed at examining the quality of delivery. Here, generally, more than 80% of the students agreed that the course stimulated their interest on the subject (Figure 7, E1), that the pace of the course was appropriate (Figure 7, E2) and that the concepts and ideas were presented and discussed clearly (Figure 7, E3).

As the last open-ended inquiry of the questionnaire, the students were asked for the suggestion and improvements of the course model. Accordingly to the answers, some of the students consider the studio course as an opportunity to improve their CAD and image elaboration skills. For some others, a higher number of architectural examples should have been examined during the theoretical lectures, whereas no negative comment about the time organization and the learning method has been recorded.


Figure 3. Objectives of the course

Figure 4. Student contribution

Figure 5. Learning environment and teaching methods


Figure 6. Learning Resources

Figure 7. Quality of delivery

4. Discussion

4.1. Questionnaire's Observations

As regards the results of the questionnaire it can be assumed that the students who participated found the model suitable in all the aspects: time organizations, teaching methods, and quality of delivery. In particular, the absolute majority of agreements have been recorded for the 1st and the 3rd sets of questions, whereas the 2nd set registered a higher level of disagreements. Here, the highest level of argument (34%) has been recorded regarding the usage of textbooks and hardcopies as course materials. This aspect may suggest the almost total usage of the internet as the main source of examples and learning materials preferred by the students.

4.2. Lecturer's Opinions

Considering the progress and the achievements of the course, in the author’s opinion can be outlined that the division of the course into 3 sessions, each with the own topic, allowed students to concentrate on the solution of a single problem at the time. Hence, this approach might be considered suitable for the sophomore students since it allows the possibility of facing the architectural problem solution step by step. By proceeding in this manner, difficulties and errors faced in the beginning, have the chance to be overcome in the following steps. For instance, once the problem of human scale, dimensional requirements, and proportions of the spaces have been solved for the 1st residential typology, its application becomes smoother in the following one, and the progress of


architectural design solutions can be implemented by further tasks.

Furthermore, for the first two typologies, the students principally exhibit the trend of solving the problem for the sequence plans, sections, elevations, 3D models, whereas, with the villa typology the requirements and the analyses have been redefined considering the architectural solution as a volumetric entity. With a background of the bidimensional organization, it became reliable for the students to consider both the aesthetic and functional aspects.

Besides the development of the individual design, during the course, theoretical lectures and research works were performed as supportive activities. In particular, has been observed that the comparison of their design with emblematic architectural projects suggested students a pathway for improvement. Therefore, the research activity assumed the role of a self-critique tool.

Lastly, the relatively short time of 5 weeks for each step culminating with a jury, suggested students to properly manage their time. As a result, the response of the students to the space organization’s design problem generally came smoother rather than in a studio course based on one-project solution per semester. However, besides the pace that seemed working properly for the management of the course some difficulties characterized the students’ performance. The difficulties involved design aspects (space organizations, graphic representation), as well as the personal approach (self-initiative for design solutions, and differentiated level of attention for different representations). Difficulties, that from an objective evaluation, might be considered common for novice students.

5. Conclusions In the present research, a model for the sophomore

architectural design studio course has been proposed. The model intends to propose an alternative solution for the consolidated practice of assigning 1 project per semester. Therefore a model, based on 3 design problems and relative juries has been defined. The procedure aspires on allowing students to: i) acquire the knowledge by practicing gradually and additionally; ii) to manage the time properly; iii) to perform research work as a form of self-critiques. The procedure has been applied during the fall semester 2019 in the Architectural Design Studio 1 at Alanya Hamdullah Emin Pasa University, Department of Architecture, and program in the English language.

To evaluate the performance of the course, a questionnaire constituted by 3 sets of questions has been submitted to the students for the evaluation. As result, the questionnaire recorded high levels of agreement for all the groups of questions, which might suggest the efficiency and the appreciation of the method. Still, in the author’s opinion, the course promoted a good pace and reached a

satisfactory level of results. However, since the procedure has been applied only once, to understand its reliability it would be beneficial to apply the model to a higher number of participants, preferably with a different background.

Acknowledgements I would like to express my gratitude to Arch. Betül

Akın Güngör for the helpful cooperation during the critiques and the juries. Likewise, I acknowledge my colleagues from Basic Design Studio courses Dr. Evren Ülkeryıldız and Dr. Nihan Kocaman Pavlovic for the continuous exchange of ideas and suggestions. Lastly, I would like to thank all the students who participated in the course and the survey.

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Habitability, a Basic Premise for Home Design and Its Impact on the Curricula of Architecture Schools

Gildardo Herrera-Sánchez, Victor Manuel Garcia-Izaguirre*

Faculty of Architecture Design and Urbanism, Autonomous University of Tamaulipas, México


Cite This Paper in the following Citation Styles (a): [1] Gildardo Herrera-Sánchez, Victor Manuel Garcia-Izaguirre , "Habitability, a Basic Premise for Home Design and Its Impact on the Curricula of Architecture Schools," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 950 - 962, 2020. DOI: 10.13189/cea.2020.080522.

(b): Gildardo Herrera-Sánchez, Victor Manuel Garcia-Izaguirre (2020). Habitability, a Basic Premise for Home Design and Its Impact on the Curricula of Architecture Schools. Civil Engineering and Architecture, 8(5), 950 - 962. DOI: 10.13189/cea.2020.080522.


Abstract The demand for housing in Mexico increases year after year, in which the architects have actively participated in its design and production. This study aims to investigate whether the architectural production generated by professionals graduated from the different three study plans of the Faculty of Architecture, Design and Urbanism of the Autonomous University of Tamaulipas has had a greater impact on the resolution of the habitability of the houses. To resolve the above issues, we apply two data collection instruments that would measure such a situation to a representative sample of the three study plans. The results obtained show that regardless of the study plan, all the graduates demonstrated to have, in addition to knowledge, capacities and skills for the design of comfortable homes, the ability to solve the aspects of habitability in the home, which breaks the paradigm that previous plans were better than current ones. This also implies the recognition of the academic process that is followed in public higher education institutions versus private schools, which is not affected by this condition; as well as the fact that the new technologies that are currently used in all disciplines have not detracted from the abilities that an architect must have.

Keywords Architect Training, Habitability of the Houses, Housing Design, Housing Production, Public Higher Education Institutions

1. IntroductionConsidering the construction of houses is a process as

complex as human nature and at the same time a vital necessity and a costly good for all the inhabitants of this planet, the present investigation has raised the fact of identifying cognitive capacities, which occurs specifically in the training of Mexican architects.

Various studies were carried out regarding housing in Mexico (Canales [1]; Cabrera [2]); Bazant [3]) have exposed the various problems facing urban areas. One of them is the phenomenon of rural migration, which has generated a population concentration in the cities. This has demanded the creation of housing, mainly in housing complexes of social interest, several of which do not meet the minimum conditions of habitability. This situation occurs when they are located in zones unsuitable to inhabit, are occupied, divided into lots and subdivided; an issue that has been stimulated in part by the low cost of land peripheral to cities, which are incorporated into them without good urban planning.

In this sense, the Housing Law, issued by the Government of Mexico in June 2006, has no clear indications regarding the parameters that should be considered to meet the habitability condition, specifying in Article 2 that "A home worthy will be considered to be one that complies… with habitable and auxiliary spaces…”; an issue that does not stipulate parameters to provide an adequate solution to housing needs.


Under the previously described, this research was proposed, with the intention to investigate whether the architectural production of homes in the southern area of the state of Tamaulipas, carried out mainly by graduates of the Faculty of Architecture, Design and Urbanism (FADU) of the Autonomous University de Tamaulipas (UAT), in the 10 years prior to 2015, considered its design, the habitability factor. This knowledge should have been acquired in the architect’s academic and professional training, even when the minimum conditions that must be fulfilled are not established under Mexican regulations, but they have been raised as necessary knowledge in Architecture schools.

Additionally, another purpose for carrying out this study was derived from the fact that in the southern metropolitan area of Tamaulipas, Mexico, there is a considerable percentage of low-income housing that was modified in its original designs. There is an interest to know if these were designed by the graduates of the FADU-UAT, or are derived from the social programs and social production of housing of the Government of Mexico.

In this sense, the main problem posed is that of detecting whether the graduates of the FADU-UAT, under the academic-professional training received, in any one of the three study plans, have marked differences in knowledge, skills or abilities, to efficiently solve the demand for housing production with adequate habitability conditions, specifically in the aspects of physical and psychological comfort, as well as the aesthetic value, essential in the design of habitable spaces.

Therefore, it was established as a general objective of the research: “Evaluate the three curricula, taught at the FADU from its foundation until the moment of conducting this research, for the discipline of Architecture, in order to compare the architectural work of the graduates of each plan in the architectural design of homes within the metropolitan area of southern Tamaulipas.”

From this the following study variables were established: Independent variable: FADU-UAT study plans (Plan

71, Mission XXI and Millenium III). Dependent variable: Architectural production of the

graduates of each plan in the generation of housing.

Two data collection instruments were designed to evaluate and analyze both variables, including abilities, tools and knowledge of graduates in this profession, in addition to analyzing their architectural production.

For the above, a study with a quantitative approach with a simple correlation analysis was considered pertinent, to check the hypothesis raised that “The different study plans for the professional training of architecture students at the FADU of the UAT, have marked differences in the production of their professional graduates, evidenced mainly in the area of housing”.

This allowed us to answer the questions that this investigation raised, which are described in more detail in

the subsequent sections.

2. Background The habitability is to architecture as reasoning is to man,

and this thought that is inextricably connected has allowed that the human being has always been able to provide a comfortable home according to his needs, adapting materials and constructive systems, in the environment in which it has had to develop, for its protection and the satisfaction of its needs, both physical, biological and psychological. This is what is now known as architecture. (Barrios [4]; Vitrubio [5])

However, within the context of architecture, there is a conceptual indeterminacy, which designates at least three different things: 1. Firstly, to the discipline that contains the knowledge,

tools, concepts, and skills of the architects' training. 2. Secondly, to the intellectual activity through which

architectural buildings or spaces are designed or projected.

3. Thirdly, to the products of this intellectual activity, mainly to identify it in a style or genre.

To clear up this confusion, Barrios [4] proposes that: “(…) It is considered that the term is the expression of the idea, the term architecture is used, regardless of the three different concepts, designating the discipline dedicated to the training of architects as architecture; as an architectural design to the intellectual process that generates habitable spaces for man; while the architectural work would be the materialized product of the architectural design”.

Considering the above, the architectural phenomenon consists of the discipline that provides the knowledge, skills and abilities for the architectural design process it produces, the buildings, or architectural spaces.

Thus, the architects must then build any construction considering habitability as the set of conditions of the architectural space that meet the needs of the human being, for the best performance of their activities. (Roux-Gutiérrez, R., Espuna-Mujica, A. & García-Izaguirre, V., [6])

According to the National Housing Commission, (acronym in spanish CONAVI), [7] between 700,000 and one million homes must be financed and built each year in Mexico.

In this context, and according to constitutional article 4, the objective of public policy for the Mexican government is to make feasible for anyone, the possibility of buying, building, remodeling or renting a home according to their economic ability and preferences.

In that sense, it is noteworthy that the House Research and Documentation Center, (acronym in spanish CIDOC), [8], has determined that the demand for housing by type of credit was 56.4% for acquired homes, 29.5% for

952 Habitability, a Basic Premise for Home Design and Its Impact on the Curricula of Architecture Schools

improvement and 14.1% for self-built housing; highlighting that the latter compared to 2012 decreased by almost 31%. This indicates an increase in the professional practice of architects for the design and construction of homes.

But for this same reason, and even if this type of building is so required, housing itself is as complex as human nature, which according to Barrios [9] is a vital necessity and an expensive asset, of which a large part of society does not have the necessary financial resources to access it.

In general, in the houses built in the metropolitan area of southern Tamaulipas, formed by the municipalities of Tampico, Madero, and Altamira, there is a high probability that the architects who graduated from Higher Education Institutions (HEI) have participated in one way or another, and produced by the most prominent developers in the region.

However, these buildings have had to adapt to find their habitability, either through extensions or adaptations, reorganizing and reconfirming the spaces, shapes, and textures.

The latter contravenes what in theory should be the architectural solutions, which, depending on the needs and activities of the future user, should be generated appropriately for them and not cause the user to adapt to a proposal of architectural space that is not projected according to their actual needs for various reasons. No matter what these reasons are, the problem is that many of these architectural solutions lack the necessary habitability conditions.

Studies carried out by other HEI report that at least 55% of its graduates work mainly in the construction industry and in second place is 13% working in government services. Among the activities the graduates carry out, the management and coordination of projects stand out with 26%, followed by supervision with 18%. (UAM, [10])

This implies that a vast majority of these professionals have been dedicated for the construction of homes at all socioeconomic levels, ranging from those of social interest to those of a residential nature. According to Espuna, Elías, Montalvo, and Rosas [11], the most significant architectural production is that of housing, where the design concept is applied from the first workshops dedicated to learning architecture.

The results obtained would imply, according to the CIDOC [8] that the HEI must take these considerations into account in order to implement and adapt them into the formative processes of the architects, so that they graduate with an integrated understanding and apply it according to the needs of the society. It would have to change in the coming years in terms of the type of housing that is built, who builds it and where it is built.

Until 2015, the time limit established for the study, the educational program of the Architect's career at FADU-UAT, has had graduates from three study plans (Table 1), who have received their names according to the

administration that established them or the requirements at the time when they were instituted.

Table 1. General characteristics of the FADU curricula

Curriculum (P.E.)

Start of P.E.

1st Generation graduated

End of P.E.

Last generation

that graduated

P-71 1971 1976 1999 2004

P-MXXI 2000 2005 2005 2010

P-MIII 2006 2011 2014 2019

Source: Prepared by the researchers in 2015

Specifically, in September 1971, the current FADU was founded, which begins with the career of Architects, whose teaching staff emerged from the College of Architects of the metropolitan area of southern Tamaulipas.

This first curriculum of FADU, Plan 71 (P-71), was strictly based on that of the UNAM National School of Architecture; ENA-UNAM created in 1967.

Issues to highlight in this plan of study are: The curriculum consisted of ten semesters, which had

a total of 59 subjects. Its central axis of knowledge with 10 subjects was that of Architectural projects, of which housing projects were developed in two subjects, with a marked tendency towards the building.

The graduate profile considered that architecture student should be prepared to lead men and companies.

The curriculum contributed to society, the resolution of urban problems, or in a particular way those of residential spaces.

The second curriculum implemented at FADU-UAT, called Mission XXI (P-MXXI), was taught from January 2000 under a model whose professional training is organized by: “(…) Training centers and within the framework of the new Flexible Curriculum model that introduced the following changes: New ways of transiting through the Study Plans, new forms of teacher participation, new ways of organizing research and linking, new ways of organization in the Faculties and Academic Units, new school management systems and, updating of university legislation (Filizola, [12]). ”

Highlights of this plan of study: The curriculum was made up of ten semesters, which

had a total of 50 subjects, its central axis being Architectural Projects with 10 subjects, of which housing projects were developed in three subjects. It is worth noting the creation of the Digital Systems nucleus with five subjects, which did not exist in the previous plan.

Total Credits to be taken 399, of which 288 credits are compulsory of named subjects; co-curricular, disciplinary and professionalizing courses and 111 credits of elective or optional subjects.


The graduate profile sought to train individuals with an innovative technical and humanistic vision, sensitive to the requirements of their social context and trained to contribute to the improvement of the habitable spaces of mankind, through the adequate solution of spatial problems and the selection of the materials appropriate to the specific environment.

The third curriculum was named, Millenium III (P-MIII), and began in 2006.

The characteristics of this plan of study are: The curriculum was made up of ten semesters, with a

total of 62 subjects, with its central axis of knowledge including 10 subjects of architectural projects, four of which were housing projects.

Total Credits to be taken 368, of which 40 credits corresponded to the optional subjects. The plan was organized in four training nuclei: University Basic that operates as a common core for the careers that are taught at the UAT and FADU and that respond to the specific requirements of a program; Professionalism, this is compulsory; Disciplinary, through which the understanding of Professional subjects is facilitated; Electives whose intention is the consolidation of a specialty or training accentuation, which can be chosen gradually through the various periods of the degree.

The graduate profile establishes a professional capable of performing in the sciences and disciplines of the design, planning, execution, and supervision of different types of architectural projects that meet the habitability needs of human beings, from the most concrete biological needs to the most abstract ethical and aesthetic. These are typical of the integral development of the potential of the individual and the communities.

The study plan enables professional skills to be developed through the acquisition and organization of knowledge, the development of abilities, skills, attitudes and values based on real problems,

integrating the contents of the different areas of knowledge from an interdisciplinary perspective.

3. Methodology According to García [13], educational research has the

ultimate objective of helping to explain and understand the phenomena that have occurred in the scholastic world in general and in the didactic act in particular.

Therefore, based on the stated objective, it was necessary to establish a methodological process, in order to define the spatial characteristics inherent in the conception of architectural design, reviewing the cognitive aspects and psychomotor skills that each curriculum contained.

According to Nadal [14], the evaluation consists in determining the extent to which the proposed objectives have been achieved, and whether the most appropriate methods have been used to achieve it.

In this sense, this research was carried out in two different and complementary phases (figure 1), which respond to the idea that, to evaluate the study plans taught for the Bachelor of Architecture at FADU since its foundation and the production of architectural graduates, they should include the following: I. A descriptive analysis of the three curricula, which

allows finding the most significant coincidences or divergences of the professional training of the architecture graduate.

II. Design and apply a data collection instrument to: a) Evaluate the curriculum, specifically about the

graduate profile, areas of knowledge, skills, abilities, tools, and knowledge and skills acquired by graduates through the thematic contents of the training subjects.

b) Analyze the architectural production of graduates of each plan in the generation of homes, according to the parameters of habitability: Physical dimensions; Spatial syntax; Physical comfort and spiritual comfort. (Barrios, [9]).


Source: Prepared by the researchers (2015).

Figure 1. Methodological scheme applied to the project.

These two different phases are interconnected, in order to obtain the results of the investigation, with which the study variables could be measured.

Regarding these two phases, it was considered pertinent that the study had a quantitative approach, since per Hernández, Fernández - Collado, and Baptista [15], the research will use data collection to test a hypothesis based on the numerical measurement and statistical analysis, to establish patterns of behavior and test theories.

In the case of phase I, it was also considered to be non-experimental, since there is no control over the independent variables, corresponding to the three different study plans, because the events have already occurred. The variation of the independent variables will be achieved not by direct manipulation but through the selection of the analysis units in which the studied variable has a presence.

Additionally, a descriptive transactional design was applied, which allowed collecting data from each plan in a single moment, in order to describe the independent variable, in order to analyze its incidence and interrelation with the dependent variable.

To finally apply a descriptive study, that seeks to specify the important properties of people, groups, communities or any other phenomenon that is subjected to analysis that, according to Hernández, et al. [15] seeks to specify properties, characteristics and important features of any phenomenon that is analyzed. It is intended to describe the why of a phenomenon and under what conditions it occurs, or why two or more variables are related.

Regarding phase II, the universe of this research consisted of all the graduates of the different study plans of the FADU - UAT architectural education program. Considering the time limit established until December

2015, the universe was 2896 graduates, according to data provided by the FADU-UAT School Department. which have been categorized by study plan (table 2), in which the percentage that represented for each of the total graduates was determined.

Table 2. Universe - shows graduates of Architecture FADU-UAT

Curriculum (P.E.)

Total graduates % Graduates Sample

P-71 2201 75% 186

P-MXXI 333 11% 27

P-MIII 362 14% 35

Total 2896 100% 248


The sample size was determined under stratified sampling based on the percentage corresponding to each plan, considering 90% reliability, 50% dispersion and 5% margin of error.

Finally, the elements of the sample were selected in a non-probabilistic way, taking into consideration the following inclusion and exclusion criteria.

Inclusion criteria: Graduates must:

Be entitled or be in the process of qualification. Be in the metropolitan area of southern Tamaulipas. Have designed or built at least one dwelling that is

currently inhabited. Have designed or built the house in the metropolitan

area of southern Tamaulipas. Have designed or built the home within the first five

years after discharge.


Exclusion criteria: Those who did not meet the inclusion criteria. Those who do not want to participate in the study.

Phase II also involved designing and applying two data collection instruments: a) The first to evaluate the curriculum, specifically

regarding the graduate profile, areas of knowledge, abilities, skills, tools, and the knowledge and skills acquired by graduates through the thematic contents of the training subjects.

b) While the second would allow comparing the architectural production of graduates of each study plan, in the generation of housing, considering exclusively the following parameters of habitability: Physical dimensions; Special syntax; Physical comfort and spiritual comfort.

Regarding the first instrument, referring to the graduate profile, the three study plans were analyzed and the coinciding factors were sought in order to homogenize and be able to have a relevant comparison between them.

While, to measure the knowledge and skills acquired by graduates through the thematic content of the training subjects, the instrument applied to the country's professionals has been taken as the base model, to design the General Examination for Graduate Studies in Architecture (EGEL-ARQUI) developed by the National Evaluation Center for Higher Education, AC (CENEVAL, [16]).

Depending on the disposition and choice of the sample element, two formats and ways were used to deliver it: I. Format printed and answered in the presence or

nearness of the researcher. II. Digital format sent via email and answered and

returned by the same means to the researcher.

As expressed by Manzano and Zamora [17] in many disciplines related to the social sciences, it is usual to try to measure highly complex phenomena such as intelligence, motivation, efficiency, perception, among others, based on perceptions, opinions, indicators and specific or approximate variables, which are called latent variables.

In the words of Monroy, Vidal and Saade [18] in the social sciences, a large part of the variables of interest in the discipline cannot be observed directly, so the latent variables and their value depend on the variables observed or manifested.

In order to solve the data analysis, the simple correlation statistical model (1) was used to measure the intensity of the linear relationship between the two study variables.

𝑟 = 𝑆𝐶(𝑥𝑦)�𝑆𝐶(𝑥)𝑆𝐶(𝑦)

… (1)

For the purposes of testing the research hypothesis, it will be taken as a reference that if the value of r > 0.7 there is sufficient evidence to accept the hypothesis, otherwise the null hypothesis will be accepted.

4. Results and Discussion The results were analyzed under the following process:

1) First, evaluating the curriculum, in the established dimensions.

2) Second, evaluating the architectural production of the graduates of each curriculum, in the generation of housing under the four parameters of habitability.

3) Third, by checking the research hypothesis, using the simple correlation between the two study variables.

A. From the first data collection instrument, the most notable results are the following:

Regarding what function they performed in their first housing project, (Table 3), it can be seen that in all the plans the largest group is that of graduates who covered the two functions of designing and building their first home, giving a total of 56.2%, while the group that only designed the house was 35.0% and finally those who only participated in its construction were 8.8%. This indicates that a large group of recent graduates were independent professionals or that they were able to work in an office in which they could do both functions, either due to the size of the company or the capabilities of the graduates.

Table 3. First professional exercise carried out by graduates FADU-UAT.

CURRICULUM Design Build Both TOTAL P-71 14 24.5% 2 3.5% 20 35.2% 36 63.2%

P-XXI 2 3.5% 1 1.8% 6 10.5% 9 15.8%

P-MIII 4 7.0% 2 3.5% 6 10.5% 12 21.0%

TOTAL 20 35.0% 5 8.8% 32 56.2% 57 100 %



Table 4. Type of housing designed / built by graduates of the Study Plans FADU-UAT

CURRICULUM Social interest Economic Middle interest Residential Residential plus TOTAL

P-71 4 7.0% 0 0.0% 20 35.1% 12 21.1% 0 0.0% 36 63.2%

P-XXI 0 0.0% 0 0.0% 6 10.5% 2 3.5% 1 1.8% 9 15.8%

P-MIII 1 1.8% 1 1.8% 8 13.9% 2 3.5% 0 0.0% 12 21.0%

TOTAL 5 8.8% 1 1.8% 34 59.5% 16 28.1% 1 1.8% 57 100%

Note: The terms: social interest, economic, middle interest, residential and residential plus; is the classification used in Mexico to differentiate the cost of a home Source: Prepared by the researchers (2015).

Table 5. Weighting scale for Graduate Profile of the FADU-UAT Study Plans

Deficient Bad Regular Good Excellent

0 - 1 1.1 - 2 2.1 - 3 3.1 - 4 4.1 - 5


Table 6. Averages obtained from the Graduate Profile in each Curriculum FADU-UAT.

AVERAGES CURRICULUM 1 2 3 4 5 6 7 8 9 10

P-71 4.3 4.2 4.0 3.8 3.8 4.0 3.7 3.8 4.2 4.4 P-XXI 4.2 4.0 4.1 4.2 4.2 4.0 3.9 3.9 4.2 4.3 P-MIII 4.0 3.8 3.5 3.4 3.7 4.0 3.6 3.4 4.2 4.3

Averages 4.16 4.00 3.87 3.80 3.90 4.00 3.73 3.70 4.20 4.33


Regarding what type of housing they designed and/or built, in Table 4 it can be seen that in all the plans the largest group is that of graduates whose first professional job was that of an average home, giving a total of 59.5%. While the second type was that of a residential home, giving 28.1%; thirdly the social interest housing with 8.8%, and lastly, the extremes of housing, economic and residential plus with 1.8% each.

Regarding the graduate profile, 10 items were determined, all on a Likert scale, to measure the perception of the graduates as to how much they had contributed the knowledge acquired during their professional training, to fulfill this profile; establishing for its measurement the scale is shown in table 5.

The averages obtained from the perception of each of the questions are shown in Table 6.

Each of the ten items, established to measure the graduation profile (Graph 1), are described below, giving the average value obtained in the three study plans. It is worth mentioning that all the results were between the perception of good to excellent: The first was aimed at establishing whether they had

forged an imaginative, creative and innovative capacity to give aesthetic architectural solutions. The average was 4.16 (excellent).

The second determined to establish if they had induced the ability to analyze and synthesize architectural phenomena with the specific characteristics of different human groups. The average was 4.00 (good).

The third would allow determining the capacity to respond with architecture to the bioclimatic and contextual conditions of each region. The resulting average was 3.87 (good).

The fourth would measure the ability to plan, schedule, budget, and manage architectural projects. The average value obtained was 3.80 (good).

The fifth would establish the ability to define the technology and construction systems appropriate to the architectural solution. The average was 3.90 (good).

The sixth would evaluate the ability to define the appropriate installation systems for the architectural solution. The average value obtained was 4.00 (good).

The seventh would estimate the capacity to build, direct and supervise the execution of architectural or urban works at their different scales. The average result was 3.73 (good).

The eighth would assess the ability to develop architectural solutions, considering the regulatory and legal requirements to carry out the work. The average was 3.70 (good).

The ninth would value the ability to discern between what is necessary and what is possible for habitable solutions. Average obtained was 4.20 (excellent)

Finally, the tenth, with an average of 4.33(excellent), established the ability to expose ideas and transform them into architectural spaces according to the principles of composition and drawing, manual or digital.



Graph 1. Graduate Profile Dimension Averages in each Study Plan FADU-UAT

Once the results of each of the items were obtained, the general average of each study plan was determined, with which the graduates considered with the best contribution to the graduation profile, (Table 7). In general terms, graduates rate it as excellent to good.

Table 7. General averages and outcome of the Exit Profile, in each FADU-UAT Study Plan

Curriculum General average Value scale

P-71 4.01 Excellent

P-MXXI 4.10 Excellent

P-MIII 3.79 Good

TOTAL 3.96 Good Source: Prepared by the researchers (2015).

Now, if it is analyzed for the three study plans together, it is observed that the item with the highest score was No. 10, having a general average of 4.33, which refers to the “Ability to present ideas and to transform them into architectural spaces in accordance with the principles of composition and drawing, manual or digital”; while the item with the lowest score was No. 7, having a general average of 3.73, which refers to "Ability to build, direct and supervise the execution of architectural or urban works on their different scales".

While, in particular, each plan stands out in the following ways (Graph 1): For the Plan 71 curriculum, the item with the highest

score was No. 10, with a general average of 4.4; while items No. 5 and No. 7 both have the same lowest score with a general average of 3.7. The first refers to

the "Capacity to define the technology and construction systems appropriate to the architectural solution," while the second one was already referred to previously.

For the Mission XXI Curriculum, the item with the highest score was No. 10, having a general average of 4.3; while both items No. 7 and No. 9 share the lowest score with a general average of 3.9. The second item refers to the "Ability to discern between what is necessary and possible for habitable solutions."

And for the Millennium III Curriculum, the item with the highest score was No. 10, having a general average of 4.3; while both items No. 4 and No. 8 share the lowest score, having a general average of 3.4. The first refers to the "Capacity to plan, program, budget and manage architectural projects"; while the second refers to "Develop architectural solutions, considering the regulatory and legal requirements to carry out the work."

Finally, in relation to the thematic contents, it was feasible to measure the knowledge and skills acquired by the graduates, based on the EGEL-ARQUI instrument, which included 45 professional tasks, in contrast to what was taught in each of the training subjects that were integrated into the different curricula.

For its evaluation, the same three scales established by CENEVAL [16] were used to perform the social validation of the EGEL-ARQUI, in accordance with the following categories and definitions: Undergraduate studies: The graduate was asked to

indicate whether during their bachelor's degree they studied the concepts, principles or procedures


necessary to carry out the task. The answer options were YES or NO; Additionally, and for the purposes of this investigation, in case the answer was YES, the graduate was asked to indicate the number of subjects in which the concept, principle or procedure was integrated, either 1, 2, 3 or 4 subjects.

Importance: Refers to how decisive the proper accomplishment of the task has been in order to perform effectively throughout your professional life. It is a scale with four response options: VI = Very important, I = Important, LI = Less important and NI = Not important at all.

Frequency: This refers to how often you do the task in your professional work during a year. It is also a scale with four response options: VF = Very frequent, F = Frequent, U = Uncommon and NF = Not frequent.

In order to carry out the analysis of each of the 45 tasks, the coding for the three established dimensions was established (Table 8), which gave a parameter between a minimum of 2 to a maximum of 13 points.

With this, it was possible to establish the scale (table 9), with which they were categorized by the Study Plan from which each student graduated.

The following results were obtained: Of the graduates of Plan 71, they perceive that two

professional tasks are Very Relevant, specifically No. 13 and No. 24. Twenty-five is perceived as Relevant, Eighteen are Not Very Relevant. And finally, zero indicated Not at all Relevant.

Graduates of the Mission XXI Plan highlighted that 15 professional tasks are Very Relevant, with the highest value being No. 24 and subsequently 9, 14, 15, 23, 25, 30 and 31 with the same value. Twenty-seven is perceived as Relevant. Three are Not Very Relevant and zero indicated Not at all Relevant.

While in the case of graduates of the Millennium III Plan, they perceive that of the 45 professional tasks, 2 is Very Relevant, specifically No. 24 and 25. Twenty-three is Relevant. Twenty is Not Very Relevant. Zero indicated Not at all Relevant.

The results indicated (table 10), show the three professional tasks that obtained the lowest value in the Not at all Relevant and Not Very Relevant categories, as well as the highest value in the other two categories for every study plan. If none is indicated, it should be considered that there were no tasks in that category.

Table 8. Coding of results for professional tasks used by graduates FADU-UAT

Undergraduate studies Importance Frequency

Y N Related subject NI LI I VI NF U F VF Points

1 0 1 2 3 4 1 2 3 4 1 2 3 4

x x x 2

x x x x 13


Table 9. Scale of results for the professional tasks used by graduates. FADU-UAT

PROFESSIONAL TASKS

Not at all relevant Not very relevant Relevant Very relevant

2 – 4.9 5 – 7.9 8 – 10.9 11 - 13


Table 10. Best / lowest professional tasks evaluated by graduates FADU-UAT.

CURRICULUM Not at all relevant Not very relevant Relevant Very relevant

P-71 - - - 39 44 45 1 9 14 13 24 -

P-XXI - - - 10 39 44 2 16 17 24 9 14

P-MIII - - - 40 44 45 10 13 1 24 25 -



A more specific analysis in relation to the three study plans, seeking matches between them, resulted in the determination of which of the 45 professional tasks were selected, although they were not necessarily among the best or worst evaluated: I. For the Very Relevant category, only one was

coincident in the three study plans, specifically No. 24 that mentions “Representing the project through plans”.

II. With respect to the Relevant category, seven tasks out of the thirty-six classified were coincident in the three study plans. These were: No. 2 "Define concepts that govern the project

according to the scope of the architectural genre."

No. 3 "Analyze representative works of the same genre and their typological characteristics".

No. 6 "Ground the architectural project by visiting and interviewing potential users."

No. 8 "Consider sociocultural, political, historical, religious and economic conditions of the different users".

No. 16 "Develop general zoning and specific areas."

No. 18 "Propose preliminary solutions of volumetry".

Nº 33 “Establish general criteria for gas installations and special criteria for the executive project”.

III. In the Not Very Relevant category, there were two coincident tasks in the three study plans that are within the eight classified as such:

No. 39 "Take the necessary actions to achieve consensus and favorable opinions on the project."

No. 44 "Implement an architectural services company".

IV. Finally, none was considered as Not at all Relevant. B. Regarding the second data collection instrument, the

main results obtained in relation to architectural production show that graduates: 1) Of the three study plans, mainly used the study

of areas to determine the dimensioning of the

spaces of the house, leaving as a second option that these were determined by the client.

2) From Plan 71 (61.1%), from Mission XXI Plan (55.5%) and Millennium III (58.3%), respected and integrated the existing trees on the land into the design of the house.

3) From Plan 71 (100.%), from Plan Misión XXI (77.8%) and Millenium III (83.3%), took into account the orientation to determine the location of the living spaces.

4) From Plan 71 (56%) and Millenium III (57%), indicate that the final result regarding the solar effects was satisfactory, while the graduates of Mission XXI Plan (54%), indicate that it was very satisfactory; (the most used elements to mitigate the sun being eaves, trees and an adequate orientation).

5) Of the three study plans differ in their perception of the dwellings’ thermal comfort. While 22% of graduates consider that the dwellings have a thermal comfort considered cool in summer, 45% of the graduates consider that the dwellings are in an intermediate thermal temperature between cool and warm.

Weighted each of the 21 items integrated in the four dimensions, the average value was obtained that gave the final result for each of the four factors, on a scale of 1 to 10 (Table 11 and Graph 2).

Table 11. Average by the curriculum of the four factors for habitability, in homes designed and/or built by FADU-UAT graduates

Average General

average P-71 P-MXXI P-MIII

Physical dimensions 7.40 8.90 7.80 8.03

Spatial Syntax 7.20 8.90 8.00 8.03

Physical Comfort 7.30 9.00 8.80 8.37

Spiritual Comfort 6.80 8.60 8.20 7.87

General average 7.18 8.85 8.20




Graph 2. Habitability Dimension Averages in each Curriculum FADU-UAT

C. Regarding the verification of the established research hypothesis, it was determined that:

In analyzing each study plan, regarding the interrelation of the two study variables, it was determined that these did not make a difference in the professional production of houses with a habitability approach.

This leads to determine with the evidence found in each of the data collection instruments applied to the graduates involved in the research, that there is insufficient evidence at the alpha significance level equal to 0.05 to accept the research hypothesis, which posed:

H1 = The different study plans for the professional training of the architecture students of the FADU of the UAT: Plan 71, Mission XXI and Millenium III; have marked differences in the professional production of their graduates, evidenced mainly in the area of housing.

Therefore, the null hypothesis had to be accepted.

5. Conclusions Houses constitute more than 70% of the urban landscape

of the cities. It is assumed that the people in charge of building this urban fabric, in which these architectural objects are included, are the architects. These professionals are dedicated to designing and projecting living spaces, with the intention of solving the problems of human habitat. They give consideration to the social, cultural, economic and technological characteristics of the moment, observing that housing is ideal and different in each society and it also

depends on the characteristics and personal needs of each individual.

The demand for housing construction in Mexico, according to CONAVI, [7] and CIDOC [8], will increase considerably in the medium term. According to these projections, it is calculated that 75% of the population will live in cities and metropolitan areas by 2030.

This will lead to the need for any graduate of architecture to face the impact of having to fill this increased demand for satisfactory living spaces. It happens that only a minimum percentage of professionals in this discipline do so directly. Most, indirectly impact other activities related to home design and construction.

It is noteworthy in the context of most cities in Mexico, that in the urban landscape, houses with poor architectural solutions have been identified and even analyzed by other researchers (Garcia, [19]). Their analysises indicate that the planning of solutions both for the housing unit and for the subdivision do not even comply with what is established by Mexican regulations. This occurs mainly in the design of social interest housing.

The latter has led to the assumption that the architects did not adequately attend to this need and therefore also cast doubt on their training as professionals. However, this research, even being a case study, reflects that the architecture graduates of the FADU-UAT, have been provided with the relevant tools and knowledge for the efficient exercise of their profession, regardless of the study plan from which they have graduated.

Regarding these graduates, when comparing the architectural production of the houses within the southern metropolitan area of Tamaulipas, and measured according


to the parameters of habitability and knowledge acquired through the thematic contents of the subjects of their academic-professional training, it has been found that this has indeed been a basic premise considered for their design.

This leads to determining that the deficiency is not in vocational training, but in the lack of opportunity that several of the recent graduates have had to be able to apply the theory and practice of what was taught in the classrooms of the university. They have to carry out tasks and functions that are related to architecture but in a phase of the design and/or construction process in which decision-making has already been made. Therefore they can do little to correct the deficiencies that can be detected in relation to the habitability of the houses.

This is due to the fact that the majority of the population and the companies dedicated to construction use graduates of architecture schools indirectly. This is for various reasons, both economic and social and cultural.

Additionally and as mentioned at the beginning of this work, the inadequate controls established in the various norms or regulations that establish the conditions for the generation of quality housing with habitability parameters, specifically developed in production, also have a negative influence on social housing for the medium and low socio - economic sector.

This leads to the conclusion that understanding architecture through practice leads to perceiving it in a critical, reflective, and creative way. The architect graduate as an apprentice, in an effort to interpret the basic concepts, is inundated with a sea of questions that are not resolved until he comes into contact with the practice of this discipline, doing architecture leads to experience and experience leads to knowledge.

REFERENCES [1] Canales Fernanda (2017) “Territorio + Vivienda Colectiva”

En Aguilar K & Esparza J (Coord) Vivienda Infonavit, Tercera época Volumen 2, Número 1; pp 66-73, Centro de Investigación para el Desarrollo Sostenible del Instituto Nacional del Fondo Nacional de la Vivienda para los trabajadores; México (En red) Disponible en: https://infonavit.janium.net/janium/Documentos/64452.pdf

[2] Cabrera Granillo D & Guillén Lúgigo M (2018) “La problematica del abandon de la vivienda de interes social en las ciudades globales, una mirada desde sus habitantes” Revista Las ciencias sociales y la agenda nacional, Volumen IX Problemas urbanos y del territorio, Consejo mexicano de ciencias sociales AC pp 313-358 UASLP, México (En red) Disponible en: https://www.comecso.com/ciencias-sociales-agenda-nacional/cs/issue/view/9/9

[3] Bazant Jan (2008) “Expansion and Consolidation urban processes on low income groups periphery zones” Revista Bitacora 13 junio-diciembre 2008, pp 117-132; Universidad

Nacional de Colombia, Bogotá (En red) disponible en: https://revistas.unal.edu.co/index.php/bitacora/article/view/18527

[4] Barrios y Ramos García, D.M. (2014). “Fundamentación para la formación de los arquitectos” En D. M. Barrios y Ramos García (Ed.), En Doctorado en Arquitectura con Orientación en Vivienda. FADU, México.

[5] Vitrubio Polión, M.L. (1995) “De Architectura. Los diez libros de arquitectura” (Oliver Domingo, J. L. Trad.) Alianza Editorial, S. A. (Obra original publicada en 15 a C.) Madrid.

[6] Roux-Gutiérrez, R., Espuna-Mujica, A. y García-Izaguirre, V. (2010), “Manual Normativo para el desarrollo de vivienda sustentable de interés social en México”, Plaza y Valdés, México.

[7] Comisión Nacional de Vivienda CONAVI (2008) “Criterios e Indicadores para los desarrollos habitacionales sustentables en México” CONAVI, México

[8] Centro de Investigación y documentación de la casa AC; CIDOC (2013) “Estado actual de la vivienda 2013” CIDOC – SHF, México.

[9] Barrios y Ramos García, D. M. (2010) “Marco de Referencia”, in Roux Gutiérrez, R., Espuna Mujica, A. y García Izaguirre, V. (Compilers), “Manual Normativo para el desarrollo de vivienda sustentable de interés social en México”, México, Plaza y Valdés.

[10] Universidad Autónoma Metropolitana UAM (2012) “Resultados de la encuesta aplicada a egresados de la Licenciatura en arquitectura” División de Ciencias y Artes para el Diseño Unidad Xochimilco- Casa Abierta al tiempo-Sistema de Información de estudiantes egresados y empleadores, UAM, México. (En red) Disponible en: http://www.uam.mx/egresados/estudios/egre2012/rep/xoc/CAD/P85_Arquitectura.pdf

[11] Espuna Mujica, A.; Elías López, P.; Montalvo Tello, S.; Rosas Lusett M. (2010) “Región húmeda, zona del Golfo, Tamaulipas” in Roux Gutiérrez, R., Espuna Mujica, A. y García Izaguirre, V. (Compilers) (2010), “Manual Normativo para el desarrollo de vivienda sustentable de interés social en México”, Plaza y Valdés, México.

[12] Filizola Haces, H. (2000) “1 Informe Rectoral” Universidad Autónoma de Tamaulipas, México.

[13] García Izaguirre, V. M. (2010) “Materiales multimedia para la enseñanza de la Geometría Tridimensional. Desarrollo, aplicación y evaluación” Editorial Académica Española, España.

[14] Nadal Cristóbal A. (2005) “El programa universitario como herramienta de evaluación” in unpublished Doctoral Thesis, Department of Pedagogy and Specific Didactics, Universitat De Les Illes Balears, España. (En red) Disponible en: http://www.tdx.cat/bitstream/handle/10803/9392/tanc1de1.pdf?sequence=1

[15] Hernández Sampieri, R. Fernández - Collado, C. Baptista Lucio, P. (2006) “Metodología de la investigación” McGraw Hill, México

[16] Centro Nacional de Evaluación para la Educación Superior, A.C CENEVAL (2014), “Encuesta de validación social. Examen General para el Egreso de la Licenciatura en


Arquitectura” CENEVAL, México

[17] Manzano Patiño, A. Zamora Muñoz, S. (2010) “Sistema de ecuaciones estructurales: una herramienta de investigación. Cuaderno Técnico 4” CENEVAL, México. (En red) Disponible en: http://archivos.ceneval.edu.mx/archivos_portal/7490/CuadernoTecnico041aed.pdf

[18] Monroy Cazorla, L. Vidal Uribe, R. y SaadeHazin, A. (2010) “Análisis de clases latentes. Una Técnica para detectar heterogeneidad en poblaciones. Cuaderno técnico 2”,

CENEVAL, México. (En red) Disponible en: http://archivos.ceneval.edu.mx/archivos_portal/7488/CuadernoTecnico021aed.pdf

[19] García Izaguirre VM, Pier Castello ML, Gonzalez Velez J & Lozano Castro RI (2018) “Viviendas en Tamaulipas: Publicidad vs realidad” en García I, Sánchez M &Espuna M (Coord) Tçópicos de la Vivienda. Una vision desde la sustentabilidad y la habitabilidad”, pp 15-40 Editorial Colofón, México


DOI: 10.13189/cea.2020.080523

Ultra-Lightweight EPS Concrete: Mixing Procedure and

Predictive Models for Compressive Strength

Fayez Moutassem

Department of Civil and Infrastructure Engineering, American University of Ras Al Khaimah, United Arab Emirates



(a): [1] Fayez Moutassem , "Ultra-Lightweight EPS Concrete: Mixing Procedure and Predictive Models for Compressive

Strength," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 963 - 972, 2020. DOI: 10.13189/cea.2020.080523.

(b): Fayez Moutassem (2020). Ultra-Lightweight EPS Concrete: Mixing Procedure and Predictive Models for

Compressive Strength. Civil Engineering and Architecture, 8(5), 963 - 972. DOI: 10.13189/cea.2020.080523.


Abstract Expanded polystyrene (EPS) lightweight

concrete is increasingly used in various applications due to

its lightweight, excellent heat preservation, sound

insulation and energy absorbing characteristics. However,

due to the hydrophobic nature and very low density of EPS

beads, EPS concretes are prone to segregation, poor

bonding, and homogeneity issues. The properties of EPS

concrete are highly dependent on the mixture proportions

and mixing procedure. This study involves the

development of a quality mixing procedure for

Ultra-lightweight EPS concrete and the development of

two predictive compressive strength models function of

concrete mixture and density, respectively. An

experimental program is developed to implement the

mixing procedure and to calibrate and evaluate the

accuracy of the models. The proposed models were found

to accurately predict the strength of concrete mixtures. The

corresponding standard error for the models is less than 0.3

MPa and the corresponding correlation coefficient is

greater than 0.93. To ensure quality control before concrete

is cast, a link between the plastic density of fresh concrete

and the compressive strength was established. Furthermore,

to accommodate tight construction schedules, the effects of

concrete age on the compressive strength development

were studied and the 28-day strength was related to

strengths at early ages.

Keywords EPS Concrete, Lightweight Concrete,

Foamed Concrete, Expanded Polystyrene, Compressive

Strength, Density, Mixture Proportioning, Mixing

Procedure

1. Introduction

There is a growing interest in using alternative

sustainable and economical materials. Expanded

polystyrene (EPS) is normally used as a packaging material

due to its low density, hydrophobic properties, good

thermal insulation, low absorption, and low cost. The

yearly global production of polystyrene is over fourteen

million tons and a very significant quantity of EPS ends up

as waste materials that are sent to landfills, which are of

limited space [1,2]. EPS concrete is increasingly being

used in various applications in the construction industry

and other industries mainly due to its lightweight, excellent

heat preservation and sound insulation [1,3]. It can be used

as base coarse materials for pavements, construction

materials for cladding panels, lightweight partition walls,

floating marine structures, sea beds, an energy-absorbing

material for protection of buried military structures, and

fenders for offshore oil platforms [4, 5, 6, 7, 8].

Ultra-lightweight EPS concrete is produced by fully

replacing the normal aggregates (fine and coarse) with EPS

beads and using other materials/admixtures to ensure

proper bonding, high flowability, good stability and good

surface finish.

The hydrophobic nature and very low-density of EPS

beads can be a disadvantage when used in concrete because

EPS concrete will be prone to segregation and poor

bonding in comparison with normal weight concretes [9].

The significantly lower stiffness of the EPS aggregates in

comparison with the cement paste will cause varying stress

distributions inside the concrete. In addition, there is a

difference between the failure pattern and the interfacial

964 Ultra-Lightweight EPS Concrete: Mixing Procedure and Predictive Models for Compressive Strength

transition zone (ITZ) for EPS concrete in comparison with

normal weight concrete. Unlike EPS concrete, failure of

normal weight concretes occurs around the aggregate

particles because the tensile strength of aggregates is

higher than that of the surrounding cement paste [2].

Because of the low bond between the EPS and the cement

paste, and hydrophobic nature and low mechanical strength

of EPS beads, there is a significant decrease in the

compressive strength of EPS concretes [7,10,11]. The

properties of EPS concrete are highly dependent on the

mixture proportions and mixing procedure. Therefore,

understanding the behavior of fresh EPS concrete and

following a proper mixing process can significantly

improve its quality, homogeneity, stability, and avoid

segregation. Furthermore, adding silica fume as a cement

replacement provides mixtures that are more cohesive and

less prone to segregation [12].

Research studies have shown that the density of EPS

concrete significantly affects its compressive strength and

that compressive strength is more sensitive to the density

compared to tensile strength and modulus of elasticity [13].

Multiple previous studies have shown that the density of

lightweight concrete is the most significant property

influencing its compressive strength where an increase in

density results in a higher compressive strength

[7,14,15,16]. Research has shown that the compressive

strength of EPS concrete increases with a decrease in EPS

bead size, for the same concrete density. However, for

lower EPS concrete densities, it was observed that EPS

bead size’s influence on the lightweight concrete

compressive strength becomes negligible [17].

Therefore, based on previous studies, there is a further

need to minimize the lack of homogeneity and stability

issues encountered through proper mixture proportioning

and mixing design process. Since the EPS concrete

behavior and failure pattern are different from normal

concretes, the models developed to predict the compressive

strength of normal concretes should not be used and

specific models should be developed for EPS concrete.

Accurate prediction of the compressive strength of EPS

concrete before concrete is cast is needed for appropriate

design of EPS concrete mixtures and for quality control

purposes. This study involves the development of a quality

mixing procedure for EPS concrete and the development of

two predictive compressive strength models function of

concrete mixture and density, respectively. An

experimental program is developed to implement the

mixing procedure and to calibrate and evaluate the

accuracy of the strength models. Furthermore, to ensure

quality control before concrete is cast, a link between the

plastic density of fresh concrete and the compressive

strength of hardened concrete needs to be stablished.

2. Experimental Program

2.1. Materials

This section presents the details for all materials used in

concrete mixtures including their technical properties. A

total 30 mixtures were fabricated. ASTM Type I ordinary

Portland cement (OPC) was used for all concrete mixtures.

The chemical and physical properties of the cement are

summarized in Table 1. Condensed silica fume (ELKEM

920D) with a 28-day compressive strength of 56 MPa and

meeting the ASTM requirements was used as cement

replacement for 11 mixtures. Commercially available Grey

colored spherical EPS beads (NEOPOR F 5300- BASF) as

shown in Figure 1 were used for all mixtures. EPS beads

size was 2.5-3.5 mm and bulk density was 15-20 kg/m3.

Polycarboxilate-based High-Range Water Reducers

(HRWR) were used to produce highly flowable concrete

mixtures. A foaming admixture (FA) was used for 24

mixtures and an air-entraining admixture (AA) was used

for 6 mixtures. A latex-based bonding agent (Planicrete

SP- MAPEI) was used for all mixtures to improve the

bonding between EPS beads and the paste.

Table 1. Chemical and Physical Properties of OPC

Properties % of Weight

SiO2 (%)

Al2O3 (%)

Fe2O3 (%)

CaO (%)

MgO (%)

SO3 (%)

Loss on Ignition (%)

Equivalent Alkalies (%)

Specific Surface Area (Blaine) (m2/kg)

Soundness, Expansion (mm)

Time of Setting-Initial (min)

Compressive Strength – 28 Days (MPa)

19.5

4.69

3.70

63.3

1.46

2.58

3.59

0.54

345

1.10

160

47.6

Figure 1. EPS Beads (NEOPOR F 5300) – Grey Color


Table 2. Concrete Mixture Design Composition

Mix # w/c EPS (kg/m3) OPC (kg/m3) SF (kg/m3) High-Range Water

Reducer (kg/m3)

Air Agent

(kg/m3) Type

1 0.24 13.8 744 0 4.10 0.0 -

2 0.25 14.0 550 0 9.60 3.0 AA

3 0.30 14.0 500 0 5.80 3.1 FA

4 0.30 14.0 500 0 4.15 2.1 FA

5 0.30 14.0 500 0 6.00 2.0 FA

6 0.30 14.0 500 0 5.80 3.1 FA

7 0.30 14.0 450 0 3.05 3.0 FA

8 0.33 15.2 400 0 1.52 3.5 FA

9 0.30 14.8 450 0 2.65 3.5 FA

10 0.30 14.8 450 0 3.20 3.0 FA

11 0.30 14.8 450 0 2.70 3.0 FA

12 0.30 14.8 450 0 1.80 3.0 FA

13 0.30 14.8 450 0 2.50 3.5 FA

14 0.30 13.9 430 0 2.50 3.3 FA

15 0.30 13.9 430 0 1.50 3.3 FA

16 0.30 13.9 430 0 1.25 3.3 FA

17 0.30 13.9 430 0 1.25 3.3 FA

18 0.30 13.9 430 0 3.15 8.8 AA

19 0.30 13.7 407 23 5.90 7.0 AA

20 0.30 13.8 407 23 1.75 7.0 AA

21 0.30 13.7 407 23 5.00 3.0 FA

22 0.30 13.8 407 23 2.18 3.5 FA

23 0.28 14.0 407 23 2.00 7.0 AA

24 0.30 13.8 407 23 1.98 7.0 AA

25 0.30 13.8 407 23 2.18 3.0 FA

26 0.30 13.8 407 23 2.18 3.5 FA

27 0.30 13.8 407 23 2.15 2.5 FA

28 0.30 13.8 407 23 2.13 2.0 FA

29 0.32 14.9 350 0 2.20 1.5 FA

30 0.32 13.5 325 30 2.20 1.5 FA

2.2. Mixture Proportions

The design variables used in proportioning the concrete

mixtures include the water-to-cementing materials ratio,

cementing materials content, which includes OPC and

Silica Fume, amount of EPS beads, amount of air

entrainment, and amount of HRWR. The range selected for

w/c was from 0.24 to 0.33. The water content values ranged

from 112 to 179 kg/m3. The cementing materials content

ranged from 350 to 744 kg/m3. Amount of EPS beads

ranged from 13.5 to 15.3 kg/m3 (56 to 63% by volume).

The amount of bonding agent was 4 kg/m3 for all mixes.

Amounts of air entrainment and superplasticizers were

varied to produce highly flowable low-density mixtures.

Corresponding proportions for the 30 mixtures are given in

Table 2.

2.3. Proposed Mixing Procedure

Mixing was performed in a horizontal pan mixer in the


laboratory. It is well known that EPS concrete is prone to

segregation mainly because of the EPS beads, which are

very low in density and high in volume fraction.

Accordingly, in this study, the ideal mixing process and

sequence was investigated and varied in order to produce

high quality homogeneous mixtures and avoid segregation.

The proposed mixing procedure is as follows:

1. Add the EPS beads to the mixer

2. Add the bonding agent to 1/3 of the water and mix

them together.

3. Pour it into the mixer and mix for 3 minutes. Note that

wetting of the EPS beads with part of the mixing

water and bonding agent is essential to ensure proper

bonding with the rest of the materials and because the

interfacial zone between cement paste and the EPS

beads play a critical role in determining mechanical

properties of concrete.

4. Pour the cementing materials and mix for 4 minutes

5. Add the foaming agent or air entrainer to the

remaining water and mix them thoroughly for 1

minute.

6. Slowly pour it into to the mixer and mix for 2

minutes.

7. Add water reducer as needed to produce high

workability and mix for 1.5 minutes.

8. Check the Slump. If the slump is as needed then

proceed to concrete casting

2.4. Casting, Curing and Testing

Concrete casting, curing and testing was consistent for

all of the concrete mixtures. The fresh concrete densities

and slump values were measured immediately after mixing

for all the concretes ASTM C138 and ASTM C143

respectively [18,19]. The concrete specimens were cast in

steel molds, followed immediately by curing at room

temperature for 24 h before being demolded. After

demolding, the specimens were cured in lime-saturated

water up to the date of testing. The density of hardened

EPS concrete test was conducted in accordance with

ASTM C567 [20] at the age of 28 days. The compressive

strength of hardened EPS concrete was measured on cube

specimens (150 mm x 150 mm x150 mm) at the age of 1, 7

and 28 days.

2.5. Calibration and Validation Procedure

The proposed models require determining of the

calibration constants. Model Calibration was carried out

by minimizing the standard error (σ) between the model

predictions and the measured experimental data. The

standard error, which provides a global assessment of the

model predictions, is defined in Equation 1 [21]:

σ = {Σ[f’cm(i) – f’cexp (i)]2 / (n - p)}

1/2 (1)

Where parameters f’cm (i) and f’cexp(i) refer to the

model and experimental compressive strength values that

correspond to mix i, respectively. Parameters n and p refer

to the number of tested points and the number of model

constants, respectively. This application provides an

assessment of the goodness of fit and the soundness of the

proposed model. In addition, the correlation coefficient

(R2), which provides a measure of the proportion of model

variability, was also calculated. Such measures permit

assessment of the capabilities of the proposed model in

predicting the trends reported in the literature.

3. Results, Discussion, and Proposed Models

3.1. Experimental Testing Results

Table 3 presents the experimental results for each mix,

which includes values for the slump, air content, fresh

density, hardened density, and compressive strength at 1, 7

and 28 days. The following sections will discuss the

relevancy of the results obtained, and present and discuss

the calibration and accuracy of the proposed compressive

strength models.


Table 3. Results of Experimental Testing

Mix # Slump (mm) Air

(%)

Fresh Density

(kg/m3)

Hardened Density

(kg/m3)

f’c1d

(MPa)

f’c7d

(MPa)

f’c28d

(MPa)

1 70 - 978 996 4.32 7.05 7.79

2 40 6 788 794 2.69 3.46 5.16

3 150 11 764 759 1.93 3.58 3.99

4 220 15 622 629 1.17 2.78 3.16

5 240 11 669 646 1.64 2.35 3.45

6 260 16 634 634 1.09 1.84 2.57

7 230 13 679 691 1.52 3.05 3.78

8 240 21 490 458 0.64 1.22 1.45

9 245 16 541 533 0.96 1.72 2.20

10 275 14 604 576 0.79 1.45 2.63

11 265 25 503 478 0.88 1.71 1.65

12 240 20 527 554 1.24 2.21 2.83

13 240 20 560 480 0.94 1.88 2.26

14 255 19 547 585 1.25 2.20 2.72

15 260 17 551 521 1.12 1.98 2.08

16 235 14 644 561 0.97 2.08 2.72

17 245 15 664 555 1.03 1.87 2.52

18 220 17 588 605 1.22 2.22 2.86

19 230 13 669 595 1.40 2.78 2.82

20 220 15 625 538 1.27 2.13 2.40

21 220 11 661 706 1.46 2.77 3.51

22 225 18 574 568 1.08 2.02 2.55

23 230 10 706 691 1.77 2.76 3.31

24 230 9 697 680 1.67 2.73 3.28

25 225 17 580 608 1.00 2.54 2.57

26 230 15 587 533 0.87 2.50 2.35

27 245 20 509 509 1.07 1.62 2.21

28 240 20 578 500 0.66 1.96 1.87

29 240 18 528 478 0.52 1.32 1.75

30 240 22 544 473 0.53 1.53 1.91

3.2. Workability and Surface Finish

The workability of fresh concrete was evaluated in terms

of the slump test. High workability was achieved for 28

mixtures to ensure ease of casting and placing. Mixtures 4

to 30 shown in Table 3 exhibited high flow characteristics

with the slump values exceeding 220 mm. Figure 2

demonstrates the slump test performed for a typical mix

and shows the high workability, consistency and stability

of the mixture. Good surface finish is very important for

EPS concrete to ensure proper bonding with other materials

especially if used as a core filling material such as for

partition walls or other purposes. Figure 3 demonstrates the

good surface finish of cast cubes for a typical mix. Good

consistency, uniformity, stability and surface finish

confirm the successful mix design and implementation of

the proposed mixing procedure.


Figure 2. Consistency of a Typical EPS Concrete Mix

Figure 3. Surface Finish for EPS Concrete Cubes

3.3. Concrete Density

Density is one of the important parameters which can

control many physical properties in EPS concrete [7,14,15].

The density and compressive strength of EPS concrete are

dominated by the porosity of specimen, which is mainly

controlled by the volume fraction of air (entrapped and

entrained), capillary porosity which depends on the water

to cementing materials ratio, and the volume fraction of the

EPS beads which are of negligible density and strength.

Accordingly, density (𝜌) and compressive strength (f’c) are

related to the mixture proportions using the following

relationship proposed in this study (Equation 2):

𝜌, f’c ∝ (w + a + eps) / cm (2)

Where w, a, eps and cm are the volume fractions of water,

air, EPS, and cementing materials in the concrete mix. The

experimental values for densities (fresh and hardened)

ranging from 458 to 996 kg/m3 are provided in Table 3 for

each concrete mixture. Figure 4 shows the relationship

between (w+a+eps)/cm and the density of hardened

concrete. As shown, an increase in the porosity results in a

decrease in the density. An R2 value of 0.86 confirms the

high significance of this relationship on the density of

concrete. Table 3 also shows that the fresh density

exceeded the hardened density for 17 mixtures. Unlike the

traditional concrete consisting of heavy aggregate,

ultra-lightweight concrete consists of EPS aggregates with

densities lower than the density of water. Any water not

consumed during the hydration process would eventually

evaporate leaving voids behind. The weight of the water

lost may have a significant effect on the overall density of

hardened ultra-lightweight concrete.

Figure 4. Relationship between Concrete Mixture and Density of

Hardened Concrete

3.4. Compressive Strength

The 28-day compressive strength values (f’c28) for the 30

concrete mixtures are given in Table 3. For the 30 mixtures,

the maximum and minimum compressive strength values

are 7.79 MPa and 1.45 MPa. Utilizing the dimensionless

relationship presented in Equation 2 and applying

statistical regression, it yields the following proposed

fundamental model for predicting the compressive strength

of lightweight EPS concrete as function of the mixture

(Equation 3):

f’c = A (B) (w + a + eps) / cm

(3)

Where A and B are calibration constants. Calibration

constant A depends on the type and strength of cement and

its unit is in MPa (or psi). Calibration constant B is a

dimensionless term, which depends on the specimen shape


and the test conditions. The values of these calibration

constants are given in Table 4. These constants were

determined by minimizing the model standard error

between the model predictions and measured experimental

values. Figure 5 shows the goodness of fit of the proposed

model (function of mixture) in comparison to the measured

experimental data. The corresponding standard error and

correlation coefficient were 0.30 MPa and 0.93,

respectively. The high degree of correlation and low

standard error are evidence of the model’s ability to predict

the compressive strength of EPS concrete as a function of

concrete mixture.

Multiple previous studies have shown that the density of

light-weight concrete is the most significant property

influencing its compressive strength [7,14,15,16].

Accordingly, the relationship between the density and

compressive strength was investigated in this study. Using

statistical regression, the following is the proposed

fundamental model for predicting the compressive strength

of lightweight EPS concrete as function of its hardened

density (Equation 4):

f’c = A (B) 𝜌 / 1000 (4)

Similarly, the calibration constant A depends on the type

and strength of cement and its unit is in MPa (or psi), and

the calibration constant B, a dimensionless term, depends

on the specimen shape and the test conditions. The values

of these calibration constants are given in Table 4. Figure 6

shows the goodness of fit of the proposed model (function

of density) in comparison to the measured experimental

data. The corresponding standard error and correlation

coefficient were 0.25 MPa and 0.96, respectively. The high

degree of correlation and low standard error are evidence

of the model’s ability to predict the compressive strength of

EPS concrete as a function of its hardened density.

In addition to the proposed predictive models, this study

establishes a link between the plastic density of fresh

concrete and the compressive strength of hardened

concrete. This is important to ensure quality control before

concrete is cast. Figure 7 presents this relationship and

shows the goodness of fit. The corresponding correlation

coefficient is 0.86.

Table 4. Calibration of Proposed Compressive Strength

Models A B σ R2


(Function of Mixture) 25.8 0.69 0.30 0.93


(Function of Density) 0.55 14.6 0.25 0.96

Figure 5. Compressive Strength Model (Function of Mixture) Vs.

Experimental Values

Figure 6. Compressive Strength Model (Function of Density) Vs.

Experimental Values

Figure 7. Relationship between Plastic Density and Compressive

Strength


3.5. Rate of Strength Development and Concrete Age

Figure 8. Rate of Strength Development

The effects of concrete age on the compressive strength

development are illustrated in Figure 8. The rate of strength

development was greater initially and decreased with time

which is similar to traditional concretes. Based on the

experimental results from this study, concrete develops

around 48% of its 28-day strength within 1-day, and 83%

of its 28-day strength within 7 days. These results show

that the rate of strength development for EPS concrete is

higher than the traditional normal density concretes. It

should be noted that 3 out of 30 mixtures (11, 26 and 28)

resulted in 7-day strength slightly exceeding the 28-day

strength. While this should not be the case, it may occur

due to the high rate of strength development, low

compressive strength values, and the sensitivity of

ultra-lightweight concrete to casting and testing in

comparison to normal concretes.

The proposed strength models (Eq. 2 and 3) were

developed and calibrated for 28-day strength only because

it is the main mix design requirement. However, the 28-day

compressive strength can be related to strengths at early

ages. This is important to accommodate tight construction

schedules. Figure 9 shows the relationships between the

28-day compressive strength versus compressive strengths

at 1-day and 7 days. The corresponding coefficients of

correlation are 0.83 and 0.89 for the 1-day strength and

7-day strength, respectively.

(a) (b)

Figure 9. Relationships between Compressive Strengths at different Ages (a) 1-day vs. 28 days, (b) 7 days vs. 28 days


4. Conclusions

In this study, a mixing procedure for Ultra-lightweight

EPS concrete was developed and predictive compressive

strength models function of concrete mixture and density

were formulated. An experimental program was developed

to implement the mixing procedure and to calibrate and

evaluate the accuracy of the strength models. This study

revealed the following main conclusions:

The proposed mixing procedure was successfully

implemented and all 30 mixtures has shown

homogeneity, stability, and no segregation.

The proposed compressive strength models provide a

good fit to the experimental data. The standard error

for both models is less than 0.3 MPa and the

corresponding correlation coefficient is greater than

0.93. These models can be utilized in the design of

concrete mixtures to meet specific strength

requirements as a priority and ensure quality control

before concrete is cast.

In order to ensure quality control before concrete is

cast, a link between the plastic density of fresh

concrete and the compressive strength of hardened

concrete was established. The corresponding

correlation coefficient was 0.86.

The effects of concrete age on strength development

were studied and the 28-day compressive strength

was related to strengths at early ages. Results reveal

that EPS concrete develops around 48% of its 28-day

strength in 1-day, and 83% in 7 days. The

corresponding correlation coefficients were 0.83 and

0.89 for the 1-day strength and 7-day strength,

respectively. This is important to accommodate tight

construction schedules.

Acknowledgements

This work was supported by the American University of

Ras Al Khaimah and Concrete Technology LLC. The

author would like to thank Concrete Technology LLC for

providing the resources to successfully conduct the

experimental part of the paper. The author would like to

thank the American University of Ras Al Khaimah for

providing additional resources and time that helped shape

up the development of the analysis and writing of the paper

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DOI: 10.13189/cea.2020.080524

Numerical Simulation of Acoustic Equation Using

Radial Point Interpolation Method with Discontinuous

Galerkin Time Integration

Kresno WS1,*

, SPR Wardani1, E Susila

2, Pranowo

3

1Department of Civil Engineering, Diponegoro University, Indonesia 2Faculty of Civil and Environmental Engineering, Bandung Institute of Technology, Indonesia

3Department of Informatics, Atmajaya University, Indonesia



(a): [1] Kresno WS, SPR Wardani1, E Susila, Pranowo , "Numerical Simulation of Acoustic Equation Using Radial Point

Interpolation Method with Discontinuous Galerkin Time Integration," Civil Engineering and Architecture, Vol. 8, No. 5,

pp. 973 - 983, 2020. DOI: 10.13189/cea.2020.080524.

(b): Kresno WS, SPR Wardani1, E Susila, Pranowo (2020). Numerical Simulation of Acoustic Equation Using Radial

Point Interpolation Method with Discontinuous Galerkin Time Integration. Civil Engineering and Architecture, 8(5), 973

- 983. DOI: 10.13189/cea.2020.080524.


Abstract The Numerical methods are research and

industrial strategies commonly used by the finite difference

method (FDM), finite element method (FEM) and finite

volume method (FVM). The technique is a mesh based or

formation of the domain. Owing to the complicated and

time-consuming nature of the mesh method in the complex

domain, it encounters numerous inconsistencies. One way

of eluding this is by the use of a meshless method. This

technique eliminates the use of but rather makes use of

nodes in the distribution of its domain. This paper

introduces the use of the radial point interpolation method

(RPIM) to approximate the acoustic equations using the

discontinuous Galerkin method (DGM) time integration. In

order to determine the numerical behaviour, its results were

simulated with the exact solution. The DGM time

integration and order of accuracy is also compared with

some commonly used procedures, such as the backward

Euler and trapezoid methods. The size of support domain

responsible for the numerical accuracy is also examined.

Finally a comparison of numerical simulations of the exact

results obtained during a specific time snapshot is

displayed.

Keywords Numerical Method, Meshless, Radial Point

Interpolation Method, Discontinuous Galerkin Method

1. Introduction

In recent times, the meshless method has attracted lots of

attention from researches seeking for ways to develop and

utilize it for numerical modelling in engineering. The

advantage of this method compared to the conventional

predecessors such as finite difference method (FDM),

finite element method (FEM) and finite volume method

(FVM) is that it does not make use of mesh. The use of

mesh in solving complex space domain shape is

complicated and time consuming [1,2].

One of the earliest commonly used in astrophysics

simulations is smoothed particle hydrodynamics (SPH), [3].

However, Diffuse-element method (DEM) is the first

meshless procedure that makes use of moving least square

on the Galerkin method [4]. EFG uses the principle of

moving least square (MLS) on Galerkin [1,5]. There is also

a reproducing kernel particle method (RKPM) which uses

kernel approximation [6].

The above mentioned procedures make use of the

moving-least-square principle, which lacks the Kronecker

delta properties. This causes difficulty in applying

boundary condition (BC). To remediate the difficulty,

several methods are proposed, some of which are the

Lagrange multipliers [1], penalty method [7], coupling

with FEM [8], collocation [9] and point interpolation

method (PIM) [10]. PIM possesses the property of

974 Numerical Simulation of Acoustic Equation Using Radial Point Interpolation Method with

Discontinuous Galerkin Time Integration

approximation function which passes through each node in

the support domain, and shape function. It also possesses

the Kronecker delta properties, which eliminates any form

of difficulties inherent the application of boundary

condition to PIM [9]. In the beginning, PIM used

polynomial as the basis function, but the appearance of

singularity inspired the usage of radial function as its basis,

thereby, converting it into the radial point interpolation

method (RPIM) [10,11].

While numerical modelling is used for time-dependent

cases, the meshless procedures are used for

space-discretization. As for time-discretization, either

explicit or implicit method should be used. One of the

difficulties associated with the forward Euler and

Runge-Kutta techniques, it is conditional stable. To

maintain stability, the width of time step (t) should be

smaller, thereby, rendering the method efficient for

numerical calculations. Furthermore, there is the implicit

method such as the backward Euler, and the trapezoidal

methods (Crank-Nicholson method), which are

unconditionally stable and as such requires greater time

step [12]. The use of meshless discretization and

Crank-Nicholson method was carried out by [13]. The

procedure was used to calculate dissipation of

consolidation, and the Biot process [14]. Nevertheless, the

choice of a large time step could lower the accuracy of the

calculation. Unfortunately, the accuracy of backward

Euler method is merely order-1, while Crank-Nicholson is

order-2, for this reason, the accuracy order of the implicit

methods needs to be developed, to improve its accuracy.

One of the high accuracy implicit techniques used for time

integration is the discontinuous Galerkin method (DGM)

[15].

This paper will discuss the development of a time and

space discretization method between radial point

interpolation method (RPIM) and discontinuous Galerkin

method (DGM). The model equation used is the

one-dimensional acoustic equation. Derivation of weak

form and time integration was being done. Simulation was

carried out by varying the number of nodes, time step, and

the size of support domain. The result of discretization

calculation using discontinuous Galerkin method (DGM) is

compared to several other standard implicit techniques

such as the Euler backward method, the trapezoidal method

and exact solution, to create a resulting numerical

behaviour.

2. Acoustic Equation

Acoustic equation, also known as acoustic wave or

scalar wave for one dimension, is presented on Eq. 1. This

equation is used to describe sounds in one dimension or 1D.

It is also similar to the SH wave problem [2]. This equation

possesses an exact solution, which could be used to test the

numerical solutions being used.

∂2𝑝(𝑥,𝑡)

∂𝑡2 − 𝑐2 ∂2𝑝(𝑥,𝑡)

∂𝑥2 = 0 (1)

Where 𝑝 is the dependent variable, which in this case is

pressure, 𝑐 is the constant of acoustic velocity, 𝑥 is the

space axis and 𝑡 represents time. Eq. 1 possesses the exact

solution which is expressed on Eq. 2 [2].

𝑝(𝑥, 𝑡) =1

2𝑝0(𝑥 − 𝑐𝑡) +

1

2𝑝0(𝑥 + 𝑐𝑡) (2)

Simulation was carried out on initial condition (IC) in

the form of Gaussian function, which exact solution would

appear as Eq. 3:

𝑝(𝑥, 𝑡) =1

2𝑒−(𝑥+𝑡)2 +

1

2𝑒−(𝑥−𝑡)2 (3)

3. Radial Point Interpolation Method (RPIM)

RPIM is a method of approach where the interpolation

function passes through nodes spread throughout the

support domain. If the value point 𝑥𝑄 (commonly Gauss

integration points) is being approached by RPIM, its

accuracy is being influenced by the number of nodes in the

support domain. To calculate the dimension of the support

domain on point 𝑥𝑄, Eq. 4 should be utilized.

𝑑𝑠 = 𝛼𝑠𝑑𝑐 (4)

Where 𝑑𝑠 the dimension of the support domain is, 𝛼𝑠 is the size of support domain expressed in dimensionless

quantity, 𝑑𝑐 is the average of distance between nodes.

RPIM interpolates 𝑢(𝑥) using nodal value on nodes

inside support domain on point 𝑥𝑄 according to Eq. 5 [16].

𝑢ℎ(𝑥, 𝑥𝑄) = ∑ 𝑅𝑖(𝑥)𝑎𝑖(𝑥𝑄)𝑁𝑠𝑖=1 = 𝐑𝑇(𝑥)𝐚(𝑥𝑄) (5)

Where 𝐚(𝑥𝑄) is constant, 𝑁𝑠 is the number of nodes on

support domain from point 𝑥𝑄 (Gauss integration point)

and basis function 𝐑𝑇 is expressed in the form of Eq. 6.

𝐑𝑇(𝐱) = [𝑅1(𝑥) 𝑅2(𝑥) … 𝑅𝑖(𝑥) … 𝑅𝑁𝑠(𝑥)] (6)

Basis function for one dimension on axis 𝑥 uses

multiquadratic (MQ) type as expressed in Eq. 7.

𝑅𝑖(𝑟𝑘) = 𝑅𝑖(𝑟) = √((𝑥 − 𝑥𝑖)2 + 𝛼𝑠𝑑𝑐

2) (7)

While 𝐚(𝑥𝑄)is expressed on Eq. 8.

𝐚𝑇(𝑥𝑄) = [𝑎1(𝑥𝑄) 𝑎2(𝑥𝑄) … 𝑎𝑖(𝑥𝑄) … 𝑎𝑁𝑠(𝑥𝑄)]

(8)

Constant 𝐚(𝑥𝑄) is the result of interpolations through

all nodes on support domain, which is expressed as matrix

form in Eq. (9).

𝐔𝒔 = 𝐑𝑸𝐚 (9)

Where moment matrix 𝐑𝑸 is expressed as a matrix in

Eq. (10).


𝐑𝑸 =

[ 𝑅1(𝑟1) 𝑅2(𝑟1) … 𝑅𝑁𝑠

(𝑟1)

𝑅1(𝑟2) 𝑅2(𝑟2) … 𝑅𝑁𝑠(𝑟2)

⋮ ⋮ ⋱ ⋮𝑅1(𝑟𝑁𝑠

) 𝑅2(𝑟𝑁𝑠) … 𝑅𝑁𝑠

(𝑟𝑁𝑠)]

(10)

The value of 𝐔𝒔 is expressed in Eq. 11.

𝐔𝑠𝑇 = [𝑢1 𝑢2 … 𝑢𝑁𝑠] (11)

The value of 𝐚(𝑥𝑄) was obtained by reversing Eq. 9

which result to Eq. 12.

𝐚 = 𝐑𝑸−1𝐔𝒔 (12)

By substituting Eq. 12 into Eq. 5, we obtained Eq. 13.

𝑢ℎ(𝑥, 𝑥𝑄) = 𝐑𝑇(𝑥)𝐑𝑸−1𝐔𝒔 = 𝚽(𝑥)𝐔𝒔 (13)

Where the shape function is expressed in Eq. 14.

𝚽(𝑥) = [𝜙1(𝑥) 𝜙2(𝑥) … 𝜙𝑘(𝑥) … 𝜙𝑁𝑠(𝑥)]

(14)

Weak Form and Spatial Discretization

To anticipate the time integration method using the

backward Euler method, trapezoidal method and DGM, the

used weak form is adjusted to produce first order ordinary

differential equation (ODE) [17]. Numerical solution using

RPIM on acoustic equation was carried out by changing Eq.

1 into two first-order equations, which are respectively

being displayed in Eq. 15a and Eq. 15b respectively, and by

introducing a new variable, 𝑎(𝑡).

𝜕𝑎

𝜕𝑡− 𝑐2 𝜕2𝑝

𝜕𝑥2 = 0 (15a)

𝜕𝑝

𝜕𝑡− 𝑎 = 0 (15b)

The RPIM solution requires the approximation of the

RPIM on the involved variables according to Eq. 16 and Eq.

17.

𝑝ℎ(𝑥) = ∑Φ𝐼(𝑥)𝑝𝐼

𝑁𝑠

𝐼=1

= 𝚽(𝑥)𝐏s (16)

𝑎ℎ(𝑥) = ∑Φ𝐼(𝑥)𝑎𝐼

𝑁𝑠

𝐼=1

= 𝚽(𝑥)𝐀s (17)

Where 𝑁𝑠 is the number of nodes on the support domain.

By approximating the unknown 𝑝 and 𝑎 in Eq. 16 and Eq.

17 using 𝑢ℎ and 𝑝ℎ and by mutliplying and integrating it

with test function 𝑤𝑙 and mesh Ω𝑝 (as linear integral), we

obtained Eq. 18a and Eq. 18b.

∫(w𝑙

𝜕𝑎

𝜕𝑡− w𝑙𝑐

2𝜕2𝑝

𝜕𝑥2) dΩ𝑝

Ω𝑝

= 0 (18𝑎)

∫(w𝑙

𝜕𝑝

𝜕𝑡− w𝑙 𝑎) dΩ𝑝

Ω𝑝

= 0 (18𝑏)

To obtain the weak form, Eq. 18a and Eq. 18b was

undertaken to reduce the order of the equations, which

produces Eq. 19a and Eq. 19b.

∫ (w𝑙

𝜕𝑎

𝜕𝑡− (

d

d𝑥(w𝑙𝑐

2d𝑝

d𝑥) −

dw𝑙𝑐2

d𝑥

d𝑝

d𝑥))dΩ𝑝

Ω𝑝

= 0 (19𝑎)

∫(w𝑙

𝜕𝑝

𝜕𝑡− w𝑙 𝑎) dΩ𝑝

Ω𝑝

= 0 (19𝑏)

By putting Eq. 16 and Eq. 17 into Eq. 19a and Eq. 19b

using w𝑙 = Φ𝐼 we obtained Eq. 20a dan Eq. 20b.

∫ (Φ𝐼

𝜕

𝜕𝑡(∑Φ𝐼𝑎𝐼

𝑁

𝐼=1

) + 𝑐2𝜕Φ𝐼

d𝑥

𝜕

𝜕𝑥(∑Φ𝐼𝑝𝐼

𝑁

𝐼=1

))dΩ𝑝

Ω𝑝

= 0 (20𝑎)

∫ (Φ𝐼

𝜕

𝜕𝑡(∑Φ𝐼𝑝𝐼

𝑁

𝐼=1

) − Φ𝐼 (∑Φ𝐼𝑎𝐼

𝑁

𝐼=1

))dΩ𝑝

Ω𝑝

= 0 (20𝑏)

Eq. 20a and Eq. 20b could be expressed by matrix

notations as displayed on Eq. 21a and Eq. 21b.

𝐁𝜕𝐚

𝜕𝑡+ 𝑐2𝐇𝐩 = 0 (21a)

𝐁𝜕𝐩

𝜕𝑡− 𝐁𝐚 = 0 (21b)

where

𝐁 = ∫

[ Φ1

Φ2

⋮

Φ𝑁]

[Φ1 Φ2 … Φ𝑁] dΩ𝑝 (22)

Ω𝑝

𝐇 = ∫

[ 𝜕Φ1

𝜕𝑥𝜕Φ2

𝜕𝑥⋮

𝜕Φ𝑁

𝜕𝑥 ]

Ω𝑝

[𝜕Φ1

𝜕𝑥

𝜕Φ2

𝜕𝑥…

𝜕Φ𝑁

𝜕𝑥] dΩ𝑝 (23)

𝜕𝐚

𝜕𝑡= [

𝜕𝑎1

𝜕𝑡

𝜕𝑎2

𝜕𝑡…

𝜕𝑎𝑁

𝜕𝑡]𝑇

(24)

𝜕𝐩

𝜕𝑡= [

𝜕𝑝1

𝜕𝑡

𝜕𝑝2

𝜕𝑡…

𝜕𝑝𝑁

𝜕𝑡]𝑇

(25)

𝐮 = [𝑢1 𝑢2 … 𝑢𝑁]𝑇 (26)

𝐩 = [𝑝1 𝑝2 … 𝑝𝑁]𝑇 (27)

4. Time Integration

Time integration is carried out in standard form using

backward Euler method, trapezoid method and

discontinuous Galerkin method (DGM). It was carried out

by multiplying each side Eq. 21a and Eq. 21b with 𝐁−𝟏,

thus we obtained Eq. 28a and Eq. 28b.



𝜕𝐚

𝜕𝑡= −𝑐2𝐁−𝟏𝐇𝐩 (28a)

𝜕𝐩

𝜕𝑡= 𝐚 (28b)

So that the backward Euler method produces Eq. 29a and

Eq. 29b, where time step Δ𝑡 = 𝑡𝑛+1 − 𝑡𝑛.

𝐚𝑛+1 − 𝐚𝑛

Δ𝑡= −𝑐2𝐁−𝟏𝐇𝐩𝑛+1 (29𝑎)

𝐩𝑛+1 − 𝐩𝑛

Δ𝑡= 𝐚𝑛+1 (29𝑏)

Using matrix notations, Eq. 29a and Eq. 29b could be

expressed as in Eq.30, where 𝐈 is the identity matrix.

[

𝐚𝑛+1

𝐩𝑛+1

] = [𝐈 𝑐2Δ𝑡𝐁−𝟏𝐇

−∆𝑡𝐈 𝐈

]

−1

[

𝐚𝑛

𝐩𝑛

] (30)

The RPIM simulation with backward Euler is carried out

by solving Eq. 30. The process is done by determining the

value of 𝐚 and 𝐩 at time 𝑛, after which Eq. 30 is inverted,

thereby, generating 𝐚 and 𝐩 values. Step time 𝑛 + 1

using an unknown 𝐩 variable is repeated to obtain the final

time.

Time integration using other implicit methods other than

backward Euler could be conducted using the trapezoidal

method. Here time integration for Eq. 28a and Eq. 28b is

being carried out using an average gradient time step 𝑛

and 𝑛 + 1, as displayed in Eq. 31a and Eq. 31b.

𝐚𝑛+1 − 𝐚𝑛

∆𝑡=

1

2(−𝑐2𝐁−𝟏𝐇𝐩𝑛 − 𝑐2𝐁−𝟏𝐇𝐩𝑛+1) (31𝑎)

𝐩𝑛+1 − 𝐩𝑛

∆𝑡=

1

2(𝐚𝑛 + 𝐚𝑛+1) (31𝑏)

Eq. 31a and Eq. 31b could be expressed in matrix as seen

on Eq. 32.

[

𝐩𝑛+1

𝐚𝑛+1

]

=

[ ∆𝑡

2𝑐2(𝐁−𝟏𝐇) 𝐈

𝐈 −∆𝑡

2𝐈] −1

[ −

∆𝑡

2𝑐2(𝐁−𝟏𝐇) 𝐈

𝐈∆𝑡

2𝐈]

[

𝐩𝑛

𝐚𝑛

] (32)

Time integration using discontinuous Galerkin method

(DGM) is applied on Eq. 21a and Eq. 21b. By multiplying

Eq. 21a and Eq. 21b with weight function 𝑣𝑙 and

integrating at the boundary [𝑡𝑛, 𝑡𝑛+1] the result is Eq. 33a

and Eq. 33b.

∫ 𝑣𝑙 (𝐁𝜕𝐚

𝜕𝑡+ 𝑐2 𝐇𝐩) d𝑡

𝑡𝑛+1

𝑡𝑛

= 0 (33𝑎)

∫ 𝑣𝑙 (𝐁𝜕𝐩

𝜕𝑡− 𝐁𝐚) d𝑡

𝑡𝑛+1

𝑡𝑛

= 0 (33𝑏)

The value of 𝐚 and 𝐩 are unknown in Eq. 33a and Eq.

33b with an independent variable time of 𝑡. The value of 𝐚

and 𝐩 were approximated by Eq. 34 and Eq. 35, giving

rise to an independent variable with coordinate 𝜉.

𝐚(𝜉) = 𝐚𝑘+𝜓1(𝜉) + 𝐚𝑘+1

− 𝜓2(𝜉) (34)

𝐩(𝜉) = 𝐩𝑘+𝜓1(𝜉) + 𝐩𝑘+1

− 𝜓2(𝜉) (35)

where

𝜓1(𝜉) =1

2(1 − 𝜉) ; 𝜓2(𝜉) =

1

2(1 + 𝜉) (36)

By substituting Eq. 34 and Eq. 35 into Eq. 33a and Eq.

33b, we obtained Eq. 37a and Eq. 37b.

∫ 𝑣𝑙 (𝐁𝜕

𝜕𝑡(𝐚𝑘

+𝜓1(𝜉) + 𝐚𝑘+1− 𝜓2(𝜉))

+1

−1

+ 𝑐2 𝐇(𝐩𝑘+𝜓1(𝜉) + 𝐩𝑘+1

− 𝜓2(𝜉)))∆𝑡

2d𝜉

= 0 (37𝑎)

∫ 𝑣𝑙 (𝐁𝜕

𝜕𝑡(𝐩𝑘

+𝜓1(𝜉) + 𝐩𝑘+1− 𝜓2(𝜉))

+1

−1

− 𝐁(𝐚𝑘+𝜓1(𝜉) + 𝐚𝑘+1

− 𝜓2(𝜉)))∆𝑡

2d𝜉

= 0 (37𝑏)

Thus Eq. 37a and Eq. 37b could be solved for 𝑣1 = 𝜓1

and 𝑣2 = 𝜓2, and expressed in matrix as seen on Eq. 38.

[ 𝑐2

3∆𝑡𝐇

1

2𝐁

𝑐2

6∆𝑡𝐇

−1

2𝐁

𝑐2

6∆𝑡𝐇

1

2𝐁

𝑐2

3∆𝑡𝐇

1

2𝐁

1

2𝐁

−1

3∆𝑡𝐁

−1

2𝐁

−1

6∆𝑡𝐁

1

2𝐁

−1

6∆𝑡𝐁

1

2𝐁

−1

3∆𝑡𝐁

]

[

𝐩𝑛+

𝐩𝑛+1−

𝐚𝑛+

𝐚𝑛+1− ]

=

[ 𝐁𝐚𝑛

−

𝐁𝐩𝑛−

𝟎

𝟎 ]

(38)

5. Numerical Example

This chapter will show the solutions of 1-dimensional

acoustic equation using RPIM-DGM and first-order time

integration. Simulation was carried out using RPIM and

time integration with backward Euler process, trapezoidal

method, and DGM. Simulation on 𝑥 axis was carried out

with 𝑥𝑙 ≤ 𝑥 ≤ 𝑥𝑟 where 𝑥𝑙 = −8.0 (left) and 𝑥𝑟 = 8.0

(right). Node was spread with the distance of ∆𝑥 . The

number of nodes used is 10, 20, 30, 50, and 100

respectively. Initital time 𝑡𝑖 = 0 ; final time 𝑡𝑓 = 4.0 ;

and time increment ∆𝑡 =2, 1, 0.5, 0.2 and 0.1.


Figure 1. Order of accuracy of RPIM-backward Euler, RPIM-trapezoid, and RPIM-DGM with Δ𝑡 = 0.5

Figure 2. Order of accuracy of RPIM-backward Euler RPIM-trapezoid and RPIM-DGM with Δ𝑡 = 0.2

Figure 3. Order of accuracy of RPIM-backward Euler, RPIM-trapezoid and RPIM-DGM with Δ𝑡 = 0.1



In Fig. 1 to Fig. 3 the simulation result displays the order

of accuracy from three different time integration. The order

of accuracy indicates the rate of convergence from

numerical method into an exact solution. The simulation

results which indicates the order of accuracy on varying

number of nodes relative to log10‖error‖2 where error =

exact - numeric is being displayed from Fig. 1 to Fig. 3.

According to these figures, the rate of convergence of

RPIM-DGM is higher than that of RPIM-trapezoid and

RPIM-backward Euler for time increments Δ𝑡 =0.5; 0.2; and 0.1. The results of the rate of convergence for

∆t = 0.1, RPIM-Euler backward is 0.95, that of the

RPIM-trapezoid is 2.58, while that of the RPIM-DGM is

3.01 as shown in Table 1. For ∆t = 0.2, RPIM-Euler

backward is 0.22, RPIM-trapezoid is 1.81 and RPIM-DGM

is 3.05. At ∆t = 0.5, the backward RPIM-Euler is 0.01, the

RPIM-trapezoid is 0.48, and the RPIM-DGM has a value

of 1.75.

Table 1 shows that for a larger time increment, order of

accuracy will diminish. On the other hand, smaller time

increment will result in higher order of accuracy.

The result of error accumulation relative to time for

RPIM-backward Euler, RPIM-Euler trapezoid and

RPIM-DGM is displayed from Fig. 4 to Fig. 6. From these

figures it could be observed that simulations with

RPIM-backward Euler, results to huge errors, while that of

RPIM-trapezoid gives a smaller accumulation error, with

RPIM-DGM having the smallest accumulation error rate.

Smaller accumulation error rate will result in a gentle

graphic line slope.

Table 1. Order of Accuracy of RPIM-Backward Euler, RPIM-Trapezoid and RPIM-DGM for Δ𝑡 = 0.1; 0.2; And 0.5 On Acoustic Equation

Method Order of accuracy

𝚫𝒕=0.5

Order of accuracy

𝚫𝒕=0.2

Order of accuracy

𝚫𝒕=0.1

RPIM-backward Euler 0.0131 0.2259 0.9523

RPIM-trapezoid 0.4889 1.8140 2.5853

RPIM-DGM 1.7462 3.0567 3.0119

Figure 4. Accumulation of error for RPIM-backward Euler RPIM-trapezoid and RPIM-DGM, 20 nodes, Δ𝑡 = 0.5


Figure 5. Accumulation of error for RPIM-backward Euler, RPIM-trapezoid and RPIM-DGM, 30 nodes, Δ𝑡 = 0.2

Figure 6. Accumulation of error for RPIM-backward Euler, RPIM-trapezoid and RPIM-DGM, 50 nodes, Δ𝑡 = 0.1

The accuracy of numerical simulation using

RPIM-DGM approach is also influenced by the size of the

support domain 𝛼s as displayed in Fig. 7, 8, and 9. A

minimum and maximum support domain size will result in

larger error.

For Δ𝑡 = 0.5 with 20 nodes, the maximum accuracy for

𝛼s ranges from 7 to 10, while for 30 and 50 nodes, the

maximum accuracy for 𝛼s ranges from 2 to 12, as shown

in Fig. 7. For Δ𝑡 = 0.2 with 20, 30 and 50 nodes, the


in Fig. 8. While for Δ𝑡 = 0.1 with 20, 30 and 50 nodes, the


in Fig. 9. In general, the more the number of nodes used,

the higher the accuracy in the wider 𝛼s range.



Figure 7. The influence of the size of support domain to error on RPIM-DGM for acoustic equation, Δ𝑡 = 0.5




The calculation result of RPIM-DGM which takes the

form of acoustic wave is being compared directly to the

exact solution and displayed for snapshot on time 𝑡=0; 1; 2;

3; and 4 as displayed in Figure 10 to 14. The pressure

which is the calculated result of RPIM-DGM is displayed

as dotted lines, while the exact solution is illustrated using

solid lines.

It could be observed from Fig.10 to 14 that the lines

representing both RPIM-DGM with coincident solution.

From Fig.10 to 14, it is observed that stability problems do

not occur with the integration of time with DGM.

Figure 10. Pressure as Gaussian function for initial condition

Figure 11. Pressure on time t=1, with 100 nodes and ∆𝑡=0.01



Figure 12. Pressure on time t=2, with 100 nodes and ∆𝑡=0.01

Figure 13. Pressure on time t=3 with 100 nodes and ∆𝑡=0.01

Figure 14. Pressure on time t=4 with 100 node and ∆𝑡=0.01


6. Conclusions

A numerical approach with RPIM and time integration

using DGM or RPIM-DGM has been carried out to

approximate a one-dimensional acoustic equation in order

to produce good results. The RPIM-DGM numerical

simulation is also compared to other commonly used time

integration approaches such as Euler backward and

trapezoid methods. In addition, the numerical method is

compared with the exact method so that its behaviour can

be identified. The results of accumulated errors for each

method show different values. The RPIM-DGM results

produces the smallest accumulated number of errors, while

the biggest accumulated number of errors is produced

using the RPIM-Euler backward technique. The size of the

domain support affects the accuracy of the RPIM-DGM

simulation. The optimal size of the support domain is 7 to

10 from the average distance between nodes. The

numerical simulation results show that the simulation does

not encounter stability inconsistencies.

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Typology of Peri-Urban Area Based on Physical and Social Aspects in Marisa, Indonesia

Irwan Wunarlan1,2,*, Sugiono Soetomo3, Iwan Rudiarto4

1Doctoral Candidate of Architecture and Urban Engineering, Universitas Diponegoro, Semarang, Indonesia 2Lecturer of Architecture, Faculty of Engineering, Universitas Negeri Gorontalo, Indonesia

3Lecturer at Postgraduate Program of Architecture and Urban Engineering, Universitas Negeri Gorontalo, Indonesia 4Lecturer at Postgraduate Program of Urban and Regional Planning, Universitas Diponegoro, Semarang, Indonesia

Received July 3, 2020; Revised September 13, 2020; Accepted October 19, 2020

Cite This Paper in the following Citation Styles (a): [1] Irwan Wunarlan, Sugiono Soetomo, Iwan Rudiarto , "Typology of Peri-Urban Area Based on Physical and Social Aspects in Marisa, Indonesia," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 984 - 992, 2020. DOI: 10.13189/cea.2020.080525.

(b): Irwan Wunarlan, Sugiono Soetomo, Iwan Rudiarto (2020). Typology of Peri-Urban Area Based on Physical and Social Aspects in Marisa, Indonesia. Civil Engineering and Architecture, 8(5), 984 - 992. DOI: 10.13189/cea.2020.080525.


Abstract Peri-urban is commonly defined as an area around the sub-urban region that has the hybrid characteristics between an urban area and a rural area. The study aimed to investigate the change of regional typology due to the progress of the peri-urban area in Marisa based on the physical and social aspects in 1980 and in 2017. Encompassing two districts, the study employed descriptive-quantitative method and analysis techniques, i.e., overlay, scoring, and spatial. The results showed thatin 1980, four districts were included in the rural frame zone (zona bidang desa) category. Moreover, seven sub-districts were categorized as rural-urban frame zone (zona bidang desa kota) while the rest were included in the rural frame zone category. In 2017, a change of typology from rural-urban frame zone to urban-rural frame zone occurred in several villages/sub-districts, i.e., Libuo, South Marisa, North Marisa, and Pohuwato. Over a span of 37 years, the typology of several sub-districts has changed from rural frame zone to urban frame zone in Libuo, South Marisa, North Marisa, and Pohuwato village/sub-district. The urban sprawl in areas in Marisa has increased the need for an integrated policy to create a balanced spatial development.

Keywords Peri-Urban Area, Spatial, Village/ Sub-district, City, Marisa

1. IntroductionPopulation growth in urban areas has instigated the need

for availability of land in the area; such a phenomenon has changed the land function from non-developed to developed (Miljkovic, Tijana & Igor, 2012). The land condition in urban areas, however, has limited capacity. As a result, regions that share their borders with an urban area are more likely to follow the urban area’s sprawl. Such regions that are influenced by an urban area’s development is defined as peri-urban. A peri-urban is an area that experiences change and adopts urban characteristics; therefore, a peri-urban is the multifunctional transition zone between a city and a village/sub-urban. In addition, the area is commonly interpreted as an area in the sub-urban region that has hybrid characteristics between an urban area and a rural area (Salem, Naoki, and Prasanna, 2019). Such hybrid characteristics are apparent in the pattern of land use, demographic characteristics, and public service/infrastructure (Rudiarto, et al., 2013). Moreover, Peri-urban is said to progress in three aspects: physical aspect (land use, infrastructure), social aspect (population density and ratio, low mortality rate, human resources rate, heterogeneity, etc.), and economic aspect (livelihood, pre-welfare proportion, etc.) (Reny; 2014; Budiyantini et al., 2016).

Marisa is the capital of Pohuwato Regency, Gorontalo Province. It is located quite far from the province capital of


Gorontalo city (158 km). Due to the far distance, it receives very little influence from the province capital. With a surplus of commodities from the agriculture, plantation, and fishery sectors, Marisa has developed into an urban region with rural characteristics. The region is located at the main section of Trans Sulawesi roads that connects two of the nationally-active regions, viz. Gorontalo and Palu. A region/city located on the main road and has surplus agricultural commodities is more likely to develop (Tacoli, 2003; Tacoli, 2004). The region is one of the regency’s main governmental sectors, particularly in Palopo sub-district. The governmental sector that was once located at South Marisa village has instigated an urban sprawl phenomenon to other districts; this, in turn, impacts the region’s physical features. The change of land use that occurs in Marisa district will be impactful towards the typology and overall development process of the region. Such a phenomenon requires a well-implemented urban area planning policy. The study aimed to identify the distribution of peri-urban area in Marisa that impacts the regional development and the progress of the region’s peri-urban typology from 1980 to 2017. The information acquired is expected to be beneficial for the local stakeholders as a reference in conducting well-planned development policies in the future. The peri-urban analysis focuses on the physical (land use) and social (population density, livelihood) aspects of the region.

2. Research Method The research was conducted in 11 villages/sub-districts

in Marisa district. The region is 5986.59 Ha2 in size; the region’s center is located in North Marisa sub-district. The research relied on primary and secondary data obtained from the Statistical Bureau of Pohuwato regency, i.e., total land use for agriculture, livelihood, and population density. The study employed a descriptive-quantitative method as well as an overlay, scoring, classification, and spatial analysis techniques. Overlay analysis was conducted to compile the secondary data that consisted of population density, developed land, livelihood, and area of agricultural land. Moreover, scoring and classification analysis was

conducted to classify the region into four typology zones: urban frame zone (zobikot), urban-rural frame zone (zobikodes), rural-urban frame zone (zobidekot), and rural frame zone (zobides) (Yunus, 2008). On top of that, the spatial analysis was involved in identifying the distribution of the peri-urban typology in Marisa, 1980-2017.

Several factors are said to contribute to the classification of a region’s urban characteristics: population density (Rudiarto et al., 2013), accessibility and public facility (Budiyantini and Pratiwi, 2016), physical aspect (land use and area of developed land), and social aspect (population density and livelihood) (Yunus, 2008).

Based on the notions above, the typology classification (Yunus, 2008) of Marisa district referred to the physical aspects (land use and developed land area) and socioeconomic aspects (population density and livelihood). The typology was classified into four zones: urban frame zone (zobikot), urban-rural frame zone (zobikodes), rural-urban frame zone (zobidekot), and rural frame zone (zobides). The data of the percentage of land use, developed land, population density, and livelihood are presented in the following Table 1.

Following the scoring process, the next step was to calculate the typology of each region from the value acquired in the previous process. The region classification (or zoning) referred to the accumulation and range of scores obtained from the data. For instance, the urban frame zone typology has 20-18 value, in which 20 is the upper limit value, and 18 is the lower limit value. The lower limit value of urban frame zone typology is one value higher than the upper limit value of the urban-rural frame zone. Such an analogy became the reference for the determination of area zoning in the region. Moreover, the urban-rural frame zone has 15-10 value, while the rural-urban and urban frame zones have 10-5 and < 5 value in respective order.

The classification process of Marisa district was observed from the region’s physical and social aspects. Therefore, the classification process applied the primary and secondary data; following that, the processed data were further classified into the region zoning criteria of Marisa district.

Table 1. Area Zoning Criteria

Activity Spatial/Area Zone

Urban Frame Zone Urban-rural Frame Zone Rural-urban Frame Zone Rural Frame Zone

(Score 4) (Score 3) (Score 2) (Score 1)

Agriculture < 25% > 25% - < 50% > 50% - < 75% > 75%

Non-agriculture > 75% > 50% - < 75% > 25% - < 50% < 25%

Developed land > 75% > 50% - < 75% < 25% - < 50% < 25% Population Density ≥ 5.000 people/km2 ≥ 3.000 - < 5.000 people/km2 ≥ 1.000 - < 3.000 people/km2 < 1.000 people/km2

Agricultural livelihood < 25% > 25% - < 50% > 50% - < 75% > 75%

Total score 20 15 10 5

Source: Yunus, 2008; Rudiarto, et al, 2013; Muta’ali, 2015; Budiyantini & Pratiwi, 2016

986 Typology of Peri-Urban Area Based on Physical and Social Aspects in Marisa, Indonesia

3. Findings and Discussion The classification process of peri-urban typology in

Marisa district refers to the region’s physical and social aspects. The result of the comparison between primary and secondary data based on the criteria from Table 1 is as follows:

Physical Aspect

In the physical aspect, the classification of peri-urban typology is conducted by determining the percentage of the area between agricultural land and land for non-agricultural uses. In particular, the classification observes on the percentage of the area of land use as well as developed land. The percentage is displayed in the following Table 2.

Table 2 below indicates that the village/sub-district with the highest and the lowest percentage of agricultural land in 1980 was Buhu Jaya (93.10%) and Maleo (28.68%), respectively. In 2000, Buhu Jaya (94.14%) remained in the region with the highest percentage of agricultural land, while Libuo (38.17%) sat at the lowest percentage. Further, in 2017, Buhu Jaya (99.76%) still remained at the top of the table of percentage of agricultural land, while East Pohuwato (26.93%) became the region with the lowest agricultural land percentage. It indicates that the villages/sub-districts in Marisa region are rural settlement areas. The distance between houses is quite far; houses are separated from lands, coconut plantations, or maize farms.

The composition of land use for agriculture is said to be one of the criteria in determining the typology of a region. Such criteria are presented in appendix 9. Employing the

criteria in Table 1, the classification result of Marisa district is as follows: 1. In 1980, four villages/sub-districts were classified

into the urban-rural frame zone, i.e., Maleo, Libuo, Pohuwato, and Teratai. On top of that, Bulangita was the only region that fell into the rural-urban frame zone. Simultaneously, the other six villages/sub-districts (Buhu Jaya, Botubilotahu Indah, South Marisa, North Marisa, Palopo, and East Pohuwato) were classified into rural frame zone.

2. In 2000, Libuo and Pohuwato were classified into urban-rural frame zone, while Maleo, South Marisa, and Teratai fell into the rural-urban frame zone. Besides, six other regions (Buhu Jaya, Botubilotahu Indah, Bulangita, North Marisa, Palopo, and East Pohuwato) were classified into rural frame zone.

3. Further, in 2017, Libuo, Pohuwato, and East Pohuwato were classified into urban-rural frame zone, while the other six regions (Maleo, Bulangita, South Marisa, North Marisa, Palopo, and Teratai) fell into the rural-urban frame zone. Also, Buhu Jaya, Bulangita, and Botubilotahu Indah were classified into rural frame zone. Based on the elaboration above, the villages/sub-districts that experienced a change of typology are Maleo (from urban-rural frame zone in 1980 to rural-urban frame zone in 2017); North Marisa, South Marisa, and Palopo (from rural frame zone in 1980 to rural-urban frame zone in 2017); East Pohuwato (from rural frame zone in 1980 to urban-rural frame zone in 2017); and Teratai (from urban-rural frame zone in 1980 to rural-urban frame zone in 2017).

Table 2. Percentage of Area of Land Use in Marisa City from 1980-2017

No Village/Sub-district Agriculture (%) Non-agriculture (%)

1980 2000 2017 1980 2000 2017

1 Buhu Jaya 93.10 94.14 82.80 6.90 5.86 17.20

2 Libuo 30.60 38.17 34.52 69.40 61.83 65.48

3 Maleo 28.68 71.28 66.19 71.32 28.72 33.81

4 Botubilotahu Indah 78.52 81.65 71.10 21.48 18.35 28.90

5 Bulangita 61.13 87.62 99.76 38.87 12.38 0.24

6 South Marisa 82.36 74.85 57.29 17.64 25.15 42.71

7 North Marisa 85.03 78.38 50.66 14.97 21.62 49.34

8 Palopo 82.37 80.45 65.17 17.63 19.55 34.83

9 Pohuwato 68.99 48.35 43.57 31.01 51.65 56.43

10 East Pohuwato 90.33 86.72 26.93 9.67 13.28 73.07

11 Teratai 39.30 70.09 62.81 60.70 29.91 37.19

Source: Base map of 1980-2017


Figure 1. Typology of the urban area in Marisa based on agricultural land use

The analysis of the composition of land use for agriculture in Marisa generates spatial classification regarding the typology of the region, as presented in Figure 1 above.

Moreover, the analysis observes the second physical aspect, i.e., use of developed and to classify the typology of Marisa region over the span of 37 years. The percentage of use of developed land is shown in the following table.

The criteria of use of developed land, as shown in Table 3, is treated as the reference in determining the region’s typology. The typology of each village/sub-district in

Marisa from 1980 to 2017 based on the use of developed land is as follows: 1. In 1980 and 2000, all eleven villages/sub-districts in

Marisa and Paguat districts were classified into the rural frame zone.

2. Further, in 2017, two villages/sub-districts (North Marisa and South Marisa) have changed into rural-urban frame zone, while the rest remained in rural frame zone typology South Marisa and North Marisa were the only regions that progressed from rural frame zone to rural-urban frame zone.


Table 3. Percentage of Area of Developed Land in Urban Areas in Marisa from 1980-2017

No Village/Sub-district Developed land (%)

1980 2000 2017 1 Buhu Jaya 5.86 5.86 7.50 2 Libuo 1.18 1.31 2.25 3 Maleo 2.87 5.03 9.41 4 Botubilotahu Indah 4.66 8.70 19.14 5 Bulangita 0.00 2.33 2.73 6 South Marisa 8.82 13.18 38.16 7 North Marisa 11.63 15.82 43.99 8 Palopo 0.06 2.91 13.79 9 Pohuwato 4.98 30.73 81.63

10 East Pohuwato 2.70 8.08 25.56 11 Teratai 0.00 1.14 8.72

Source: Base map of 1980-2017

The above table displays that Pohuwato underwent relatively rapid development, with a high percentage of developed land area (81.63 percent as per 2017). Since the sub-district has an area of 78.65 hectares, the region is considered to have high settlement density, in which the distance between houses is one meter or less. The regions

are also considered as the supporting area of Marisa due to its function as the central business district. In 2017, the regions in second and third rank were North Marisa and South Marisa, with a percentage of the developed land area of 43.99 percent and 38.16 percent, respectively. Both sub-districts are the central region of Marisa since all the infrastructure and public utilities that serve the community of Marisa region are built in these locations.

Meanwhile, in the same year, Libuo was the region with the lowest percentage of the developed land area since the region has the largest area of 1,975.85 hectares with a relatively small population (1,473 people). Libuo is industrial development in Pohuwato regency; facilities of maize and coconut food product processing are built within the region. Moreover, Libuo is located nearby the Panua natural reserve. Therefore, the build-up area in the location is restricted.

The typology shift that occurred in villages/sub-districts in Marisa is caused by housing/settlements building construction, migration, and availability of public infrastructure. The spatial typology is illustrated in Figure 2.

Figure 2. Typology of Urban Area in Marisa based on Developed Land


Analysis of Social Aspects in Marisa Table 4. Urban Population Capacity in Marisa from 1980-2017

No Village/Sub-district Population Density (people/km2) 1980 2000 2017

1 Buhu Jaya 142 133 127 2 Libuo 17 24 29 3 Maleo 26 37 47 4 Palopo 5 57 161 5 Teratai 127 269 390 6 Bulangita 4 27 161 7 South Marisa 1615 1107 674 8 North Marisa 1629 2074 2453 9 Botubilotahu Indah 438 848 1196

10 Pohuwato 1745 2560 3252 11 East Pohuwato 142 208 264

Average Density 535.47 667.55 795.80

Source: Statistical Bureau of Pohuwato Regency (processed)

In the social aspect, the regional zoning refers to the indicators of population density and livelihood. Data on population density is acquired from the total population in each village/sub-district per region area; meanwhile, data of livelihood is obtained from the percentage of the community’s livelihood in the region. Table 4 shows the population density of Marisa from 1980 to 2017. The table also informs that in 2017, Pohuwato district was the most population-dense region of Marisa due to its function as the

embryo of Marisa region. It also acts as the destination area for new settlers looking for better livelihood in the region. The second and third-most dense regions are North Marisa and South Marisa; the regions are the central business district of Marisa area.

As presented in the previous Table 4, the population density in Marisa over the span of 37 years is elaborated as follows: From 1980 to 2017, Pohuwato was the region with the highest population density (3,252 people/km2); the region is mostly known of its fisheries commodity. Meanwhile, Libuo, as the region with a vast plantation area, was at the bottom with the lowest density (29 people/km2); the region is well-known to have coconut and maize plantations

The typology of regions in Marisa based on population density is as follows: 1. In 1980, three villages/sub-districts were classified

into rural-urban frame zone, while the rest eight regions fell into rural frame zone (see appendix).

2. Further, from 2000-2017, the typology in Marisa did not see significant changes, except South Marisa and Botubilotahu Indah. South Marisa changed from the rural-urban frame zone in 2000 to a rural frame zone in 2017. In the meantime, Botubilotahu Indah progressed from the rural frame zone in 2000 to the rural-urban frame zone in 2017.

Figure 3. Typology of Urban Area in Marisa Based on Population Density


Table 5. Percentage of Livelihood in Marisa City from 1980-2017.

No Village/Sub-district Agricultural sector (%)

1980 2000 2017 1 Buhu Jaya 83.72 80.29 75.72 2 Libuo 73.58 71.20 69.17 3 Maleo 76.65 72.33 73.23 4 Botubilotahu Indah 77.07 75.08 72.65 5 Bulangita 79.83 76.16 71.22 6 South Marisa 74.11 70.01 68.44 7 North Marisa 71.31 69.41 71.72 8 Palopo 82.26 72.24 71.69 9 Pohuwato 79.23 73.32 69.87

10 East Pohuwato 81.04 75.08 73.01 11 Teratai 82.71 76.05 64.17

Source: Statistical Bureau of Pohuwato Regency and National Socioeconomic Survey Data (processed)

Further, Table 5 displays information on the community’s livelihood in Marisa. Agriculture is among the community’s main livelihood in the region. In 1980, Buhu Jaya (83.72%), Palopo (82.26%), and Teratai (83.72%) had the highest rate of people working in the agriculture sector. The regions are composed mostly of agriculture areas, while most of the community members are farmers with quite large farmland. Meanwhile, North Marisa (71.31%) was the region with the lowest percentage

of livelihood in the agriculture sector. The regions are mainly composed of businesses, the industrial sector, and public infrastructures. Therefore, the agricultural lands in the regions are limited.

From the period of 1980, 2000, to 2017, Buhu Jaya was the region with the highest rate of people working in the agriculture sector, with a percentage of 83.72%, 80.29%, and 75.72% in respective order. Buhu Jaya is considered a suburban area that has a huge portion of land for agriculture. In the same time frame, South Marisa was the region with the lowest rate of livelihood in the agriculture sector, with a percentage measuring at 74.11%, 70.01%, and 68.44%, respectively. The regions are located in the central business area and have limited agricultural land, similar to the North Marisa sub-district.

Based on the livelihood, the typology in 1980 illustrates that only Libuo, South Marisa, and North Marisa were classified into rural-urban frame zone while the rest was classified into a rural frame zone. In 2000, six villages/sub-districts were classified into rural-urban frame zones. The rest five regions fell into the rural frame zone typology. In 2017, ten villages/sub-districts were classified into rural-urban frame zones. The rest one region fell into the rural frame zone typology.

Figure 4. Typology of Marisa from 1980-2017 based on livelihood in the agriculture sector.


Analysis of Social and Physical Typology of Marisa City

The classification of typology in Marisa region employs map overlay and scoring methods. The typology is illustrated in Figure 5.

Based on Figure 5 above, in 1980, four regions (Buhu Jaya, Botubilotahu Indah, Palopo, and East Pohuwato) were classified into rural frame zone, while other regions fell into the rural-urban frame zone. In 2000, Libuo, Maleo, South Marisa, North Marisa, Pohuwato, and Teratai were

classified into rural-urban frame zone. Further, three villages were classified into rural-urban frame zone in 2017, i.e., South Marisa, North Marisa, and Pohuwato. Over 37 years, it is apparent that the change of typology occurs in several regions. Regions that were once classified as rural frame zone changed into rural-urban frame zone, while regions that were once classified into rural-urban frame zone progressed into the urban-rural frame zone. The detailed elaboration of typology change in regions in Marisa is described as follows:

Figure 5. Regional typology of Marisa district from 1980-2017 based on physical and social aspects.


1. In 1980, four regions were included in the rural frame typology, i.e., Buhu Jaya, Botubilotahu Indah, Palopo, and East Pohuwato, while the other regions were classified as rural-urban frame zone (Libuo, Maleo, Teratai, Bulangita, North Marisa, South Marisa, and Pohuwato).

2. In 2000, the typology remained in the same zone. 3. Further, in 2017, Buhu Jaya remained in the same

typology, while Libuo, South Marisa, North Marisa, and Pohuwato progressed from rural-urban frame zone to urban-rural frame zone. Moreover, six of eleven regions (Botubilotahu Indah, Bulangita, Palopo, and East Pohuwato) experienced a change of typology.

Figure 5 describes the typology of Marisa region for the period of 1980, 2000, and 2017.

The various typology change in the region is caused by several factors: (1) limited budget of physical construction that forces the government to focus on the construction of governmental offices or public service buildings; (2) the economic activity that relies highly on the primary agricultural activities, providing minimal contribution or multiplier effect towards the community’s welfare state and regional development; (3) lack of synergy in urban planning policies; and (4) very wide range of development control that makes it hard for the development plan to reach hinterland regions.

4. Conclusion Central to a city’s urban development is the region’s

physical and social aspects. In line with this, Marisa has experienced quite a progress regarding urban development in the region. Based on the physical and social aspects, in 1980, four villages/sub-districts were classified into rural frame zone, i.e., Buhu Jaya, Botubilotahu Indah, Palopo, and East Pohuwato, while the rest were included in rural-urban frame zone. On top of that, in 2000, all regions in Marisa fell into rural frame zone typology. Over 37 years, the typology of several villages (Libuo, South Marisa, North Marisa, and Pohuwato village/sub-district) has changed from the rural-urban frame zone to urban-rural frame zone. The classification of peri-urban typology elaborates on the range of influence of urban activity from North Marisa sub-district to the outermost part of Marisa, i.e., Buhu Jaya and Bulangita.

On top of that, the urban sprawl is observed to spread gradually to the outside of Marisa region, i.e., in Duhiadaa and Buntulia districts. Therefore, the government of Pohuwato regency is required to formulate spatial planning policies regarding the impact of urban sprawl on other districts. Such conducts function to control the land use in the region and to maintain the regional development to comply with the regional objectives.

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of the Peri-Urban Interface: Perspectives on an Emerging Field. Environ. Urban., 15, 135–148.

[2] BPS., 2016. Kecamatan Marisa Dalam Angka [Marisa District in Numbers]. BPS Kab. Pohuwato.

[3] BPS., 2016. Kecamatan Paguat Dalam Angka [Paguat District in Numbers]. BPS Kab. Pohuwato.

[4] Budiyantini, Y and Pratiwi, V., 2016. Peri-urban typology of Bandung Metropolitan Area. Procedia: Social and Behavior Science. Science Direct. pp: 833-837.

[5] Miljkovic, J.Z., Tijana, C and Igor, M., 2012. Land use Planning for Sustainable Development of Peri Urban Zones. Spatium International Review, No. 2. pp: 15-22.

[6] Nela.A.K (2013). Klasifikasi Tipologi Zona Perwilayahan Wilayah Peri-Urban di Kecamatan Kartasura [Classification of Peri-urban Typology in Kartasura District]. Jurnal Wilayah dan Lingkungan, 1(3) 251-264.

[7] Reny Yesiana (2014). Typologies of Peri-Urban Klaten-Central Java: Based on Socio-Economic Perspective. The Indonesian Journal of Planning and Development, 1(1), 57-64

[8] Rudiarto. I, Handayani. W, Pigawati. B dan Pangi (2013). Zona Peri Urban Semarang Metropolitan:Perkembangan dan Tipologi Sosial Ekonomi []. Jurnal Tata Loka, 15(2), 116-128

[9] Salem, M., Naoki, T., Prasanna, D., 2019. Analyzing the Driving Factors Causing Urban Expansion in the Peri-Urban Areas Using Logistic Regression: A Case Study of the Greater Cairo Region. Infrastructures, 4(4). pp: 1-14.

[10] Yunus, H. Sabari., 2008. Dinamika Wilayah Peri Urban: Determinan Masa Depan Wilayah Kota. Yogyakarta. Pustaka Pelajar.


Characterizations and Modeling the Influence of Particle Size Distributions (PSD) of Glass Powder on

the Mechanical Behavior of Normal Strength Concrete

Brwa Omer*, Jalal Saeed

Department of Civil Engineering, College of Engineering, University of Sulaimani, Sulaymaniyah, 46001, Kurdistan Region of Iraq *Corresponding Author: [email protected]


Cite This Paper in the following Citation Styles (a): [1] Brwa Omer, Jalal Saeed , "Characterizations and Modeling the Influence of Particle Size Distributions (PSD) of Glass Powder on the Mechanical Behavior of Normal Strength Concrete," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 993 - 1005, 2020. DOI: 10.13189/cea.2020.080526.

(b): Brwa Omer, Jalal Saeed (2020). Characterizations and Modeling the Influence of Particle Size Distributions (PSD) of Glass Powder on the Mechanical Behavior of Normal Strength Concrete. Civil Engineering and Architecture, 8(5), 993 - 1005. DOI: 10.13189/cea.2020.080526.


Abstract In this study, a comprehensive experimental investigation and modeling were carried out to examine the impact of two different grain size distributions of glass powder (GP) ((55 µm < GP-A < 135 µm) and (55 µm > GP-B)) in various percentages up to 30% on the mechanical characteristics of concrete at different testing ages (7, 28,56, and 91 days). The experimental data observed were utilized to develop different models for characterizing the compressive, splitting, and flexural strength behavior of concrete modified with GP. Results indicated that, up to 25% of cement replacement with GP, the difference in particle size of GP does not have a substantial impact on the mechanical performance of concrete if it is less than 135 μm. Irrespective of GP particle size and the curing days, the increasing percentage of GP replacement up to 10% for compressive strength and up to 15% for splitting and flexural tensile strength tends to marginally reduce compressive, splitting, and flexural tensile strength at 28 days by 4%, 8%, and 6%, respectively. The developed models were found to be well predicted by curing ages, water to binder ratio (w/b), and GP content. Based on the model parameters, the percentage of GP to partially replace cement is much more effective than the particle size of GP, w/b, and curing time in changing the mechanical properties of normal strength concrete. The analytical results were in good agreement with the experimental investigation.

Keywords PSD, Glass Powder Content, Curing

Time, Cement Replacement, Strengths, Modelling

1. Introduction Concrete is currently considered to be the most

frequently used building material. It is also considered as the world's second most frequently used material after water [1]. According to Glavind [2], each year, almost 10,000 million tons of concrete have been used, and this amount will keep growing.

Cement manufacturing is considered as one of the primary industrial sectors contributing to releasing carbon dioxide emissions into the atmosphere, accounting for about 8% of global annual carbon emissions [3]. Nayana and Kavitha [4] reported that the production of cement is 2.5% rising annually, and between 2006 and 2050 the amount of its production is expected to rise from 2.55 billion tonnes to 3.7-4.4 billion tonnes. Consequently, the amount of CO2 emissions will be effectively increased. It is clear, therefore, that a successful approach for decreasing the environmental footprint of the industry is the use of alternative or cementing materials as partial cement substitution (SCMs).

Due to its chemical composition, which is rich in silica content and amorphous phases of silica, waste glass in the powder form can act as a pozzolanic material in the

994 Characterizations and Modeling the Influence of Particle Size Distributions (PSD) of Glass Powder on the Mechanical Behavior of Normal Strength Concrete

hydrating cement environment to provide a product that has certain characteristics of Portland cement. [5]. As a result, utilizing GP to replace a partial amount of cement powder can have various environmental benefits.

Various research has been conducted to investigate the possibility of using GP waste to replace cement [6-10]. It has been shown that the viability of GP as a cement substitution depends on its pozzolanic reactivity, which in turn depends on several factors such as chemical compositions, degree of crystallinity (amorphousness degree), grain size distributions and specific surface area, and percentage level of GP used as cement replacement.

Among these factors and for the mechanical properties of concrete, considerable attention has been paid to the grain size distributions and percentage replacement of GP. Mechanically, the effect of these two factors can be evaluated by using a strength activity index.

Ramezanianpour [11] pointed out, the pozzolanic activity of any pozzolanic materials can be evaluated mechanically by using the strength activity index as it is described in ASTM (C 311). Bignozzi et al. [12] have stated that the pozzolanic reactivity of the addition can be assessed by using the activity index, which must be greater than or equal to 75% at 28 days of curing.

Investigations have shown that the particle size distribution of GP has a significant effect on the different concrete properties. This is because of its direct effect on Alkali-Silica Reaction (ASR) occurrence in concrete. The probability of ASR expansion in concrete can be reduced when particle sizes of GP used decreased [8, 14]. Reference to Federico and Chidiac [13] reveal that the pozzolanic behavior of GP was firstly observed at particle sizes approximately less than 300 μm. Kalakada and Doh [15] reported that the pozzolanic properties of GP are similar to those of other materials like metakaolin, silica, and fly ash [16, 17], enables GP to have a suppressive effect on the ASR development in concrete. Based on the experimental investigations, Kalakada and Doh [15] also, stated that the glass with particle sizes of approximately 300 μm exhibited insignificant ASR occurrence, which is consistent with a maximum particle size of 300 μm for ASR occurrence that indicated by [14, 18, 19, 20].

A study by Shi et al. [7] and Schwarz and Neithalath [21] observed that, after 90 days of curing, the pozzolanic reactivity of GP could be higher than fly ash when using low percent replacement levels of GP with particles less than 100 μm. However, other researchers have reported that the favorable particle size of GP to be considered as a pozzolanic material is 75μm or less [22-24, 45]. Meyer et al. [25] contended, however, that glass below 45 microns could become pozzolanic.

Shao et al. [8] observed the size effect of GP when three different particle sizes (150 μm, 75 μm, and 38 μm) of the same type of GP were used as a partial replacement of cement. The percentage replacement of cement by GP was 30% by volume. They indicated that the increase of the

particle size of GP tends to the decreasing of the compressive strength. Shi et al. [7] evaluated the pozzolanic behavior of four waste GP from a glass beads manufacturer to replace cement by 20%. They noticed that the finely ground GP showed very high pozzolanic activity. Mirzahosseini and Riding [26] indicated that GP with a size of particles between 0 to 25 μm was shown to have increased strength activity and more portlandite consumption compared to GP with a size 25 to 38 μm and 63 to 75 μm. Recently, Jiang et al. [27] used GP having different particle sizes (75 μm and 150 μm) and substitutions (up to 80% by weight of cement) to experimentally study the pozzolanic behavior of GP at various testing ages (7, 28, and 91 days). They observed that there is a linear reduction in both compressive and splitting tensile strength with the increased replacement percentage. Also, both the particle size of GP showed almost similar compressive strength at respect ages of the test. The strength reduction in high weight/volume replacement is attributed to the lack of Calcium Hydroxide (CH), which is essential for the production of secondary Calcium Silicate Hydrate during the pozzolanic reactivity process [28].

A review of past studies indicates that there is no agreement on the optimal GP percentage to replace cement. The reason could be because the pozzolanic behavior of GP relies on several factors, as previously stated. Besides, a comprehensive study has not been conducted to investigate and quantify the effects of GP particle sizes and content, water to binder ratio, and curing time on the compressive, splitting, and flexural tensile strength of concrete. The paper aims (i) to characterize the effect of the particle size distributions (PSD) and various percentage amounts of waste GP used to partially replace cement by weight on the mechanical characteristics of concrete at different curing times. (ii) To quantify the effect of various independent variables governing the mechanical behavior of concrete modified with glass powder (GP-concrete).


2.1. Material Properties

2.1.1. Cement

The cement type used was ordinary Portland cement (OPC) from the Tasluja Cement Co. (Iraq, Kurdistan-Region, Sulaimani City, North of Iraq, 35.6265° N, and 45.2119° E) with a strength grade of (42.5 R) complying with Iraqi standard (IQS/5/1984) [29]. The chemical and mineralogical compositions of used cement and GP are presented in Table 1. With the use of Laser Particle Analyzer, the grading curve of cement was also determined (Figure 1).


(a)

GP-B Cement GP-A

(b)

Figure 1. (a) Particle size distribution curves of cement, GP-A, and GP-B, (b) Waste glass powder after milling and cement used in this study.

2.1.2. Fine aggregate (Sand) Washed river sand of (Ranya district in Sulaimani

Governorate located in the Northeast of the Kurdistan Region of Iraq, 35°33′0″N, and 45° 26′0″E) was used. It is bulk specific gravity (SSD), and dense-dry density values were 2.69 and 1875 kg/m3, respectively. It was prepared according to graded sand requirements ASTM C136 [30] specification.

2.1.3. Coarse aggregate (Gravel) Crushed gravel from (Piramagrun town, northwest of

Sulaimani city- Kurdistan region of Iraq) was used with a nominal max. size of 12.5 mm, bulk specific gravity (SSD)- of 2.49, and dense-dry density of 1600 kg/m3. The physical tests were carried out according to ASTM designations. The grain size distribution of both sand and gravel was performed and confirmed with ASTM C136 [30] and ASTM C33 [31] standard specification (Figure 2).

(a)

(b)

Figure 2. Grain size distribution for aggregates according to ASTM C33 limits. (a). Sand and (b). Gravel

Table 1. Chemical composition for Tasluja Cement and glass powder (GP) with requirements of ASTM C618 for pozzolans used in this study.

Chemical Composition Chemical Formula OPC (%) GP (%) ASTM- C618 Lime Cao 61.66 9.868 Silica SiO2 19.83 74.03

Alumina Al2O3 4.48 1.023 Ferrite Fe2O3 2.32 0.108

Magnesia MgO 3.14 4.739 Sulfur trioxide SO3 2.57 0.13

Potassium oxide K2O 0.68 0.198 Sodium oxide Na2O 0.19 8.024

Loss on Ignition LOI 1.5 1.83 Tricalcium silicate Ca3SiO5 59.50 Dicalcium silicate Ca2SiO4 11.98

Aluminate Tricalcium Ca3Al2O6 7.95 Tetracalcium Aluminoferrite Ca4Al2Fe2O10 7.05

SiO2 + Al2O3 + Fe2O3, min. % 75.16 70 SO3, max. % 0.13 4

Moisture content, max. % - 3 Loss on ignition, max. 1.83 10


2.1.4. Glass powder (GP) The GP used was obtained from local waste windows

building glasses, which are typically well-known as soda-lime glass. For preventing the undesirable effect of alkali-silica reaction and getting the acceptable pozzolanic behavior, the waste glass was ground to pass a 140 µm sieve. For this purpose, it was being crushed and ground by a ball mill in the laboratory. The milled glass was then sieved to have the preferred particle sizes as shown in Figure 1b.To evaluate the effect of the particle size of the same GP, two different particle sizes were used (GP-A and GP-B); (GP-A) having particles passing (140-micron) sieve and retained on (56 microns) sieve. While (GP-B) having particles passing sieve No. 230 (63 microns). The chemical analysis of the GP used was determined by the XRF technique (Table 1). The grain size distribution curves of GP were also determined using Laser Particle Analyzer, as shown in Figure 1; and it was found that GP-B has particle sizes of less than 55 μm. The specific gravity of GP was found to be 2.51 and 2.505 for GP-A and GP-B, respectively. These values are far less than 3.15 for used OPC. Following ASTM C 618 specifications [44], as shown in Table 1, the GP is likely to work as a desirable replacement for cement.

2.2. Experimental Program

The experimental program mainly involves two parts. The first part includes investigating the influences of partially replacing cement with GP having two different particle sizes on different strength characteristics of concrete. In the second part, based on the obtained data from the first part, the effect of various independent

variables governing the mechanical behavior of GP-modified concrete was quantified and discussed.

2.3. Mixture Proportion and Preparation

For achieving the objective of the research work, thirteen mixtures were prepared. Details for each mixture are described in Table 2. Mixes were prepared using an electric tilting mixer with a capacity of 0.08 m3 following ASTM C192 [32] standard procedures. Before the mixing process and for each mixing batch, the glass powder was mixed thoroughly with cement.

2.4. Curing and Testing Method

All specimen samples were made and cured under ASTM C192 [32] standard specifications. A universal testing machine (CONTROLS type) was used to test concrete cylinders with (100x200) mm for compressive and splitting tensile strength and prisms with (100x100x500) mm for flexural strength. The loading rate used to test compressive strength, splitting tensile strength, and flexural strength were 0.3 MPa/s, 0.023 MPa/s., and 0.02 MPa/s. respectively.

2.5. Experimentally Observed Data

A total of 78 data points from experimental work were observed; 52 data points from the compressive strength test, 13 data points from the tensile splitting strength test, and 13 data points from the flexural strength test. Each data point is based on an average value of three measured data of the same concrete specimens. The above data includes measurements for concrete samples without GP.

Table 2. Mixture proportion for 1m3 of concrete

Specimen Details

Cement (kg)

Sand (SSD) (kg) Gravel (SSD) (kg)

Water (kg)

GP Water/binder (W/C+GP) GP-A GP-B % (kg)

CR 331.0 929.93 848.0 188.67 - 0.57

A5 B5 314.5 926.30 926.26 848.0 188.67 5 16.55 0.57

A10 B10 297.9 922.72 925.34 848.0 188.67 10 33.10 0.57

A15 B15 281.3 919.12 919.01 848.0 188.67 15 49.65 0.57

A20 B20 264.8 915.52 915.37 848.0 188.67 20 66.2 0.57

A25 B25 248.2 911.91 911.74 848.0 188.67 25 82.75 0.57

A30 B30 231.7 908.31 908.10 848.0 188.67 30 99.3 0.57


2.6. Modeling

2.6.1. Non-linear models Regression analysis was made to develop different

non-linear models to predict compressive, splitting, and flexural strength of GP-concrete. The primary independent parameters considered in the regression analysis were compressive strength of reference normal concrete 𝑓𝑓𝑐𝑐(̅𝑁𝑁𝑁𝑁) , water to binder ratio (w/b), percentage of GP (GP% by weight of cement), and curing ages (t). Based on the proposed models, the effects of these independent parameters on the mechanical properties of the concrete are quantified.

2.6.2. Vipulanandan and Hoek-Brown correlation models Based on the analysis of the experimental data,

Vipulanandan correlation model [33-35] (Eq.1) and Hoek-Brown correlation model [36, 37] (Eq. 2), can be successfully used for predicting and correlating the splitting tensile and the flexural tensile strength with the compressive strength of concrete modified with GP.

𝑌𝑌 = 𝑘𝑘 + 𝑥𝑥𝑛𝑛+𝑚𝑚∗𝑥𝑥

(1)

𝑌𝑌 = 𝑥𝑥 + 𝑞𝑞 �𝑟𝑟 ∗ 𝑥𝑥𝑞𝑞

+ 𝑠𝑠� 𝑣𝑣 (2)

in which 𝑌𝑌 in both Equations is the dependent variable (splitting strength (𝐹𝐹𝑡𝑡(𝐺𝐺𝐺𝐺)) or flexural strength (𝐹𝐹𝑟𝑟(𝐺𝐺𝐺𝐺))), k, n, m, are the model parameters of Eq. 1, x in both Equations is the independent variable (compressive strength of GP-concrete 𝐹𝐹𝑐𝑐(̅𝐺𝐺𝐺𝐺)). q, r, s, v, are the model parameters for Eq. 2.

2.6.3. Model prediction accuracy The coefficient of determination (R2), Root Mean

Squared Error (RMSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Integral absolute error (IAE) were used as the prediction accuracy.

𝑅𝑅2 = � �∑ (𝑚𝑚𝑖𝑖−𝑚𝑚�𝑖𝑖)(𝑝𝑝𝑖𝑖−𝑝𝑝�̅�𝑖)𝑛𝑛𝑖𝑖=1 �

�∑ (𝑚𝑚𝑖𝑖−𝑚𝑚�𝑖𝑖)2 ∑ (𝑝𝑝𝑖𝑖−𝑝𝑝𝑖𝑖)2𝑛𝑛𝑖𝑖=1

𝑛𝑛𝑖𝑖=1

�

2

(3)

𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅 = �∑ (𝑚𝑚𝑖𝑖−𝑝𝑝𝑖𝑖)2𝑛𝑛𝑖𝑖=1

𝑛𝑛 (4)

𝐼𝐼𝐼𝐼𝑅𝑅 = ∑ �(𝑚𝑚𝑖𝑖−𝐺𝐺𝑖𝑖)2�12

∑𝑚𝑚𝑖𝑖. 100 (5)

𝑅𝑅𝐼𝐼𝑅𝑅 = ∑ |𝑚𝑚𝑖𝑖−𝑝𝑝𝑖𝑖|𝑛𝑛𝑖𝑖=1

𝑛𝑛 (6a)

𝑅𝑅𝐼𝐼𝑀𝑀𝑅𝑅 = 1𝑛𝑛∑ �𝑚𝑚𝑖𝑖−𝐺𝐺𝑖𝑖

𝑚𝑚𝑖𝑖�𝑛𝑛

𝑖𝑖=1 (6b)

Where: 𝑚𝑚𝑖𝑖 = Observed data; 𝑚𝑚�𝑖𝑖 = Average of observed data 𝑝𝑝𝑖𝑖 = Predicted data; �̅�𝑝𝑖𝑖 = Average of predicted data; 𝑛𝑛 = Number of data


3.1. Experimental Results

3.1.1. Compressive strength (ASTM C39 [38]) Figures 4 through 7 present the results of the compressive

strength test for concrete containing different percentages (5% to 30%) and particle sizes (GP-A and GP-B) of GP to replace cement at several testing days (7, 28, 56, and 91). From Figures 4 and 5, it can be generally noticed that whatever the curing age and particle sizes of GP, the use of GP tends to decrease the compressive strength of specimens. However, with increase GP content from 5% to %10, the compressive strength of the specimens decreased marginally relative to the control specimens. Beyond 10% GP replacement, the compressive strength of the concrete specimens has progressively decreased. The gradual reduction in compressive strength was due to the increased amount of water with an increased GP percentage replacement, which was not used for hydration reaction. Furthermore, as GP substitution increases, the amount of cement content is reduced, resulting in a small quantity of calcium hydroxide (CH) being produced during the hydration reaction [41]. At the early age of strength development (7 days of testing), the compressive strength of specimens contains GP-A (up to 10%) is relatively higher than those of GP-B but similar to the control specimen (Figures 6 and 7). The reason could be due to the positive action of that type of GP (GP-A) as a filler material.

Figure 4. Influence of curing age on the compressive strength of GP-A modified concrete

Figure 5. Influence of curing age on the compressive strength of GP-B modified concrete


Figure 6. Impact of GP-A on concrete compressive strength at various ages

Figure 7. Impact of GP-B on concrete compressive strength at various ages

Considering strength activity (activity index) recommended by ASTM C618 for evaluating the pozzolanic activity of GP-concrete at 28 days of curing, up to 25% for GP-B and up to 20% for GP-A can be considered and used as a pozzolanic material as shown in Figures 8 and 9.

Figure 8. Effect of GP-A on strength activity index.

Figure 9. Effect of GP-B on strength activity index.

Although GP-B has smaller particle sizes than GP-A, up to 25% of the replacement and at different curing ages except for 7 days, the compressive strength values obtained from both particle sizes were almost close to each other. This implies that the size effect of GP on the compressive strength does not contribute significantly. This observation is in agreement with findings by Letelier et al. [40]. They found that the size of GP has a more significant effect on the physical properties such as absorption, porosity, and capillarity of mortar than on the mechanical properties. However, considering the development of compressive strength values from 7 to 91 days of curing, it can be found that the pozzolanic reactivity of smaller particle size (GP-B) is relatively higher than that of GP-A (Figure 10).

Figure 10. Particle size effect of GP on the development of compressive strength at various replacements

3.1.2. Splitting tensile strength (ASTM C496 [39]) Figure 11 shows the effect of the two used PSDs and

percentages of GP replacing cement on the splitting strength of concrete on the 28th day. The results generally indicate that the variation in the particle sizes of the GP does not contribute to a significant difference in the values of the concrete tensile strength. One can observe that, with a substitution of up to 15%, the tensile strength of GP-A is slightly higher than that of GP-B even that the particle size of the latter is smaller. However, beyond the 15% replacement, the effect is reversed. The reason could be that the replacement of GP-A up to 15% could have dual positive functions, which are, physically, acting as a filler


material to increase the compactness of the concrete during casting by working with fine particles of the concrete components. At the same time, acting, chemically, as the pozzolanic behavior at the time of hydration. However, beyond which, these features will be minimized. Compared to the control specimen and irrespective of particle size distribution, there is a relatively small reduction in the splitting strength with increasing percentage replacement of GP up to 15%. After that, a noticeable reduction in tensile strength can be observed.

Figure 11. Effect of replacing cement with GP on splitting strength of concrete. The error bars represent the standard deviations of three specimens

3.1.3. Flexural tensile strength (ASTM C78 [42])

Figure 12 shows the test results of the flexural strength of concrete containing various percentages and PSD of GP at the age of 28 days. Unlike the splitting tensile strength, up to 20% replacement, GP-B has high flexural strength compared to GP-A. Beyond that, both types have almost the same values. Compared to the reference concrete, up to 15% of replacement and for GP-A, the reduction value of flexural tensile strength slightly decreased, which is about 6%. Further reduction, which ranges from 12% to14%, can be seen when the dosage of replacement increased from 15% to 30%. However, the GP-B at 5% substitution gives flexural strength higher than that provides by the reference concrete. The percentage increase is about 1%. After that, by increasing the amount of replacement from 5% to 20% results in a relatively minor decrease in flexural strength, which is 1% and 7%, respectively. The percentage reduction in the flexural strength is 14% when the percentage replacements are 25% and 30%, respectively.

Figure 12. Effect of replacing cement with GP on flexural strength of concrete. The error bars represent the standard deviations of three specimens

3.2. Model Analysis

3.2.1. Compressive strength models In this study, two models were developed to predict the

compressive strength of GP-concrete. In the first model (Eq.7), two significant parameters, which are the percentage amount of GP and the compressive strength of the control specimen, are considered. Whereas in the second model (Eq.8), the influence of water to binder ratio (w/b), percentage replacement of GP (GP %), and curing time (t) are taken into consideration.

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) = 𝐼𝐼 𝑓𝑓𝑐𝑐(̅𝑁𝑁𝑁𝑁)

𝑎𝑎

𝐺𝐺𝐺𝐺 𝑏𝑏 (7)

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) = 𝐿𝐿 �𝑤𝑤𝑏𝑏�𝐺𝐺

(𝑡𝑡)𝑍𝑍 + d �𝑤𝑤𝑏𝑏�𝑒𝑒

(𝑡𝑡)𝑓𝑓 (𝐺𝐺𝑀𝑀)𝑊𝑊 (8) In which 𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) is the cylindrical compressive strength of

GP-concrete in (MPa), 𝑓𝑓𝑐𝑐(̅𝑁𝑁𝑁𝑁) is the cylindrical compressive strength of concrete without GP in (MPa), (𝐼𝐼,𝑎𝑎,𝑎𝑎𝑛𝑛𝑎𝑎 𝑏𝑏), and 𝐿𝐿,𝑀𝑀,𝑍𝑍, 𝑎𝑎,𝑤𝑤, 𝑒𝑒,𝑎𝑎𝑛𝑛𝑎𝑎 𝑓𝑓 are model parameters of the Equations (7) and (8), respectively. The second model (Eq. 8) is also used to quantify the impact of w/b, test age (t), and percentage replacement of cement by GP on various mechanical properties of GP-concrete.

The first model (Eq. 7) was proposed by Mohammed [43] for measuring the compression strength of concrete containing recycled PET waste. While the second model (Eq. 8) was previously suggested by Ghafor et al. [37] for predicting different strength behavior of mortar modifies with silica fume and evaluating the effect of curing time, the ratio of water to cement, and the percentage of silica fume on different strength and durability properties of cement mortar with or without silica fume. In the current study, the two mentioned models are developed so that they give the proper relation between dependent and independent variables.


3.2.2. Quantification of the effect of different parameters To quantify the influence of w/b ratio, curing days (t),

particle size distributions, and percentage amount of GP (GP %) on compressive strength, Equation (8) is used. On the basis of the experimental data obtained and through the use of non-linear relationships, Equations (8a) and (8b) were obtained for each particle size of the GP (GP-A and GP-B) used, respectively. The model parameters were estimated by using the Least Squares Method of multiple regression analysis.

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺)𝐴𝐴 = 10.94 𝑡𝑡0.1409

�𝑤𝑤𝑏𝑏�1.476 − 109.5059 𝑡𝑡0.0493 (𝐺𝐺𝐺𝐺)1.6853

�𝑤𝑤𝑏𝑏�0.0466

(8a)

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺)𝐵𝐵 = 10.94 𝑡𝑡0.1409

�𝑤𝑤𝑏𝑏�1.476 − 41.6257 𝑡𝑡0.0493 (𝐺𝐺𝐺𝐺)1.110

�𝑤𝑤𝑏𝑏�0.0448

(8b)

From the model parameters observed for both Equations (Eqs. 8a and 8b), it can be said that regardless of the particle sizes of GP, the compressive strength is significantly affected by GP%. This can be observed by investigating the model parameter w in the Equations (8a) and (8b), w = 1.6853 and 1.110 respectively. While w/b and curing time are less effective than GP content. By comparing the combined effect of w/b and the curing time factors (f and e) in the Equations (8a) and (8b), (f = 0.0493 and e = 0.0466) and (f = 0.0493 and e = 0.0448) respectively, the w/b and curing time have the same impact on the compression strength of both (GP-A and GP-B). There is a reverse proportional relationship between increased compressive strength with an increased percentage of w/b and GP.

The comparison of the measured and the predicted compressive strength values for both GP-A and GP-B is shown in Figure 13. One can observe that there is a good relationship between tested and calculated compression strength (R2 = 0.97 and 0.95) for both GP-A and GP-B, respectively. Also, the line of best fit for both GP-A and GP-B is nearly close to each other (Figure 13). This implies the possibility of proposing an Equation for predicting compressive strength without taking into account the size effect of GP. This observation reinforces the experimental results obtained in this study.

Figure 13. Comparison of the measured and predicted compressive strength of GP-modified concrete using Equations (8a) and (8b).

3.2.3. The effect of PSD on compressive strength From experimental and analytical results, it was

observed that the difference in particle size distributions of GP does not have a significant effect on the strength development values of concrete replaced cement with GP up to 25%; therefore, to propose a formula for the prediction of compressive strength without taking into account the particle size effect of GP, Equation (7a) is proposed. The model factors were determined from the Least Squares Method of multiple regression analyses. The relationship between measured and calculated compressive strength by using Equation (7a) with the prediction accuracy is shown in Figure 14.

Figure 14. Test and calculated compressive strength using Equation (7a).

To quantify the impact of w/b, test age (t), and percentage replacement of GP (GP %) on the compressive strength without considering for particle sizes of GP, Equation (8c) is proposed. Figure 15 shows the relationship between the compressive strength measured and calculated using the Equation (8c).

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) = 0.2715 𝑓𝑓𝑐𝑐(̅𝑁𝑁𝑁𝑁)

1.1844

𝐺𝐺𝐺𝐺 0.2119 (7a)

𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) = 10.94 𝑡𝑡0.1409

�𝑤𝑤𝑏𝑏�1.476 − 76.2633 𝑡𝑡0.0112 (𝐺𝐺𝐺𝐺)1.3855

�𝑤𝑤𝑏𝑏�0.0483

(8c)

Figure 15. Test and calculated compressive strength using Equation (8c).


Based on the model parameters A, a, and b (0.2715, 1.1844, and 0.2119) obtained from Equation (7a), the compressive strength of the GP-concrete is primarily dependent on the combined effect of the compressive strength of the control specimen and GP%. The considerable effect of the GP on the compressive strength of GP-concrete cannot, therefore, be ignored.

Based on the model factors e, f, and w (0.0483, 0.0112, and 1.3855) obtained from Equation (8c), GP% has a visible impact on the compressive strength value. While w/b and curing age, comparatively, does not have a noticeable effect. It can also be found that the age of the test (curing time) is not a prominent parameter when quantifying the compressive strength of GP-concrete.

The proposed Equation (8c) compared to Equation (7a) has better relationships between predicted and measured compressive strength, as shown in Figure 16.

Figure 16. Test and calculated compressive strength using different proposed Equations (7a and 8c)

It is essential to be said that Equation (7a) can only be used to estimate the compressive strength of GP-concrete, while Equation (8c) can be used to estimate the compressive strength of both normal and GP-concrete. Considering the prediction accuracy of the proposed Equations (7a) and (8c), as shown in Figure 16, they can acceptably predict the compressive strength of GP-concrete.

3.2.4. The prediction of splitting and flexural strength To highlight the role of concrete parameters other than

compressive strength, Equation (8) is developed to be used for predicting the splitting tensile strength (Eq. 8d) and the flexural tensile strength (Eq. 8e) of GP-concrete. In both Equations, the effect of the water to binder ratio (w/b) and curing age (t) in addition to the GP content is quantified. However, the impact of the particle size of GP is not taken into consideration. The reason is that, similar to compressive strength, it has a relatively small effect on the values of splitting and flexural tensile strength obtained experimentally.

𝑓𝑓𝑡𝑡(𝐺𝐺𝐺𝐺) = 1.5113(𝑡𝑡)0.1172

�𝑤𝑤𝑏𝑏�0.7532 − 0.7975 (𝑡𝑡)0.101 (𝐺𝐺𝐺𝐺)0.8602

�𝑤𝑤𝑏𝑏�0.5888 (8d)

𝑓𝑓𝑟𝑟(𝐺𝐺𝐺𝐺) = 4.1773(𝑡𝑡)0.019

�𝑤𝑤𝑏𝑏�0.5809 − 0.3138 (𝑡𝑡)0.5695 (𝐺𝐺𝐺𝐺)1.3162

�𝑤𝑤𝑏𝑏�1.3521 (8e)

Figures 17 and 18 present the comparison between the tested and calculated splitting and flexural tensile strength for the proposed Equations (8d) and (8e), respectively. Also, the accuracy of the proposed Equations was obtained and listed in Table 3. Based on the statistical parameters R2 and RMSE for Equation 8d (0.916 and 0.059) and Equation 8e (0.85 and 0.13), the two Equations are shown to have an acceptable relationship between the data tested and those predicted.

Figure 17. Test and calculated splitting tensile strength using the proposed Equation (8d)

Figure 18. Test and calculated flexural strength using the proposed Equation (8e)

Table 3. Statistical performance measures for the proposed Equations.

Proposed Equation

IAE (%)

MAE (MPa)

RMSE (MPa)

MAPE (%)

Fig. No.

8c 4.096 1.417 1.73 4.55% 15

8d 1.55 0.048 0.059 1.57% 17

1a 2.033 0.062 0.077 1.99% 19

2a 2.190 0.067 0.078 2.16% 19

8e 2.103 0.121 0.13 2.11% 18

1b 2.896 0.165 0.180 2.90% 20

2b 2.931 0.157 0.184 2.94% 20

Based on the constant coefficients obtained for Equations (8d) and (8e), the GP% is much active than w/b and curing


days in changing the splitting and flexural tensile strength of GP-concrete. Both w/b and curing days have a similar impact, although their effects on increasing or decreasing the splitting and flexural tensile strength are small.

3.2.5. Correlation between compressive and splitting strengths

Based on the analysis of the experimentally obtained data, both Vipulanandan and Hoek-Brown correlation models were developed (Eqs. 1a and 2a) to correlate between compressive strength and splitting tensile strength of GP-concrete (Figure 19).

𝑓𝑓𝑡𝑡(𝐺𝐺𝐺𝐺) = 1.6164 + 𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺)

16.071+0.2087 𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) (1a)

𝑓𝑓𝑡𝑡(𝐺𝐺𝐺𝐺) = 𝑓𝑓𝑐𝑐̅(𝐺𝐺𝐺𝐺) − 0.0551�−0.6179 𝑓𝑓𝑐𝑐 (̅𝐺𝐺𝐺𝐺)

−0.0551− 0.9668�

1.0654 (2a)

From Figure 19 and depending on the accuracy predictions obtained for both developed models, as shown in Table 3, they have almost the same accuracy. Therefore, both models have nearly the same prediction for the relationship between the compressive strength and the flexural tensile strength of GP-concrete.

Figure 19. Correlation between compressive strength and splitting strength of GP-concrete

3.2.6. Correlation between the compressive and flexural tensile strengths

Likewise splitting tensile strength, Vipulanandan and Hoek-Brown correlation models were developed to represent the variation of the flexural tensile strength (𝑓𝑓𝑟𝑟(𝐺𝐺𝐺𝐺)) with compressive strength (𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) ) . Equations (1b) and (2b) represent Vipulanandan and Hoek-Brown developed correlation model, respectively

𝑓𝑓𝑟𝑟(𝐺𝐺𝐺𝐺) = 0.4339 + 𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺)

2.3482+0.1196 𝑓𝑓𝑐𝑐̅(𝐺𝐺𝐺𝐺) (1b)

𝑓𝑓𝑟𝑟(𝐺𝐺𝐺𝐺) = 𝑓𝑓𝑐𝑐(̅𝐺𝐺𝐺𝐺) − 3.4795 (−0.655 𝑓𝑓𝑐𝑐 (̅𝐺𝐺𝐺𝐺)

−3.4795− 0.0204) 1.1298

(2b)

The accuracy performance measures for the two developed models were obtained and summarized in Table

3. The variation of flexural strength with compressive strength was represented by the use of both Equations (1b) and (2b), as shown in Figure 20. Both Equations have nearly the same accuracy for predicting flexural strength as a function of the compressive strength of GP-concrete.

Figure 20. Relationship between compressive strength and flexural tensile strength of GP-concrete

4. Conclusions In this study, the influence of the two different grain size

distributions of the same type of waste GP in different percentages (5% to 30%) on the mechanical behavior of concrete was investigated. By using experimentally observed data, various models have been developed to evaluate and correlate different mechanical characteristics of GP-concrete. The comparisons between the proposed Equations were also made.

The following conclusions are drawn based on the experimental and analytical results: 1) The difference in particle size distributions of GP has

no significant impact on the values of compressive, splitting, and flexural tensile strength of concrete replaced cement with GP up to 25%, provided that the particle sizes of GP are less than 135 µm.

2) Whatever the particle sizes of GP and age of test, the strength activity index decreases with increasing GP content. However, the decreasing rate is minimal up to 10%.

3) The acceptable GP content to be used as a cement replacement is 10% considering compressive strength at 28 days, environmental benefits, and cost-effectiveness. At 28 days of testing, the compressive strength of both particle sizes of GP (GP-A and GP-B) was found slightly lower (approximately 4% and 3%, respectively) than the reference concrete specimen. However, at the same age, the acceptable GP% is 15% when splitting, and flexural tensile strength is considered.

4) Experimental results indicated that, among different concrete parameters considered, the percentage of cement replacement by GP was found to have more


effects on compressive, splitting, and flexural tensile strength compared to its particle size distributions. This indication agrees with the analytical results obtained in this study.

5) There is excellent potential for the use of powdered waste glass as a partial replacement for cement in the concrete industry.

6) The particle size effect on the prediction of various strength characteristics of concrete was found to be small so that it can be neglected when it is smaller than 135 μm.

7) GP % is much more effective than curing time and w/b to decrease or increase the compressive, splitting, and flexural strength of concrete incorporating GP.

8) Both curing days and w/b were found to have similar effects, although their effects on changing the splitting and flexural tensile strength were small.

9) The different strength behavior of GP-modified concrete was well predicted in terms of w/b, curing time, and GP%. The analytical results were in good agreement with the experimental results.

Funding This research received no external funding.

Acknowledgments The authors are grateful to Ahmed Mohammed, of

Sulaimani University, Kurdistan-Iraq, for providing valuable information on the analytical models used in this study.

Conflicts of Interest The authors declare no conflict of interest.

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Development of Freeway Weaving Areas Microsimulation Model (FWASIM)

Mahdi Alkubaisi

Civil and Infrastructure Engineering Department, Faculty of Engineering and Technology, Al-Zaytoonah University of Jordan, Jordan


Cite This Paper in the following Citation Styles (a): [1] Mahdi Alkubaisi , "Development of Freeway Weaving Areas Microsimulation Model (FWASIM)," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1006 - 1018, 2020. DOI: 10.13189/cea.2020.080527.

(b): Mahdi Alkubaisi (2020). Development of Freeway Weaving Areas Microsimulation Model (FWASIM). Civil Engineering and Architecture, 8(5), 1006 - 1018. DOI: 10.13189/cea.2020.080527.


Abstract Comprehensive analysis of traffic behavior requires continuous studies to develop traffic theories explaining that behavior at the microscopic level. The study aims to develop a microsimulation program to evaluate the freeway weaving performance depending on the observed data. FWASIM represents a microscopic analysis of the freeway traffic features. It scans events periodically. The developed FWASIM involves the formulation of driver and vehicle behavior at freeway link, on-ramp, off-ramp, and combine them to produce a flexible, friendly use simulation model. Its concept is mainly depending on the car following and lane change theories. Analytical model validation was conducted based on a comparison of FWASIM output with the VISSIM output. Tests consider the important factors that may affect the traffic behavior for a given segment configuration. The obtained results show agreement between FWASIM and VISSIM outputs. Besides, the field data were used to validate FWASIM. Graphical and t-test methods were used to examine the results. The results are statistically significant which implies that the model provides reasonably accurate measures of effectiveness for the validated range of input data.

Keywords Weaving Area, FWASIM, Lane Change, Car Following, Validation

1. IntroductionFreeways are considered as the most important elements

in the highway system network. Freeway weaving areas

represent the critical sections that affect highway capacity and performance. A comprehensive analysis of driver behavior and vehicle attributes within the weaving areas is essential. Such analysis requires continuous studies for development theories to explain the traffic behavior at the microscopic level.

Intelligent Transportation System (ITS) manages and processes the real-time traffic data to be used for the development of online traffic management and operation strategies. To face the increase in traffic congestion, accidents, and transportation delay, a field testing solution is required which is costly and cumbersome. Therefore, microscopic traffic simulation model is considered as a suitable tool to develop vast numbers of online traffic management strategies.

This research paper aims to develop a microsimulation program to evaluate the freeway weaving area performance depending on the observed data. For this reason, the weaving sections of the main freeway named “Mohamed Al-Qasim” street located in Baghdad city were chosen to collect data. Observed data were abstracted, analyzed and then processed to be used as default values throughout the steps of simulation model development.

2. Research MotivationDespite of the availability of variety numbers of

microsimulation models, the need for building new or developing the existing programs is still vital task due to the continuous changes in the traffic network. In addition to that reason, the existing microsimulation models are


operating based on traffic parameters, which are not conforming to that, observed locally, especially the driver parameters. Driver decision play an important role in the position and the speed of each vehicle, which is also influenced by external factors relating to the roadway geometry and traffic interaction. This reason motivates developing simulation models based on the local parameters, observed data, and predicted formulae.

3. Some Available Microsimulation Models

Herein below is a brief description of some microsimulation packages, which are used for the analyzing and modeling freeway weaving sections.

VISSIM is a time step based microscopic simulation model developed to analyze the full range of traffic facility operations. The model has been designed for analyzing and modeling transport networks of any size and traffic systems for all functionally classified highways. It can also model a full range of traffic modes such as, passenger cars, buses, light rail, heavy rail, airport facilities, trucks, pedestrians, and bicyclists. The model was developed at the University of Karlsruhe, Germany during the early 1970’s [7].

INTEGRATION model was used as an integrated simulation and traffic assignment model during the mid 1980’s. The model’s approach utilized the same logic for traffic flow to represent both freeway and signalized links. The model represents the traffic flow as a series of individual vehicles follow the macroscopic traffic flow. For this reason, the model is being considered mesoscopic [10].

TRANSIMS is a mesoscopic simulation model, which consists of supporting models, and databases that use

advanced techniques to be able analyzing and simulating the integrated transportation system environment. It contributes to the solution of the complexity inherent in transportation issues. Such contributions are that the simulation results addressing traffic congestion, air pollution, energy consumption, traffic safety, and so forth [9].

CORSIM is a microscopic simulation model that tracks the position and movement of each vehicle in the network once each second designed for the analysis and modeling of freeways, networks and basic transit operations. The Federal Highway Administration (FHWA) has developed CORSIM in the mid 1970’s. It is a windows-based interface software as it runs within a software environment called the Traffic Software Integrated System (TSIS). The model output can be viewed graphically and assess its performance using animation [12].

4. Model Formulation The model was developed to include the formulation of

driver and vehicle behavior at freeway link, on-ramp (merge region), off-ramp (diverge region), forming the highway weaving area, and finally, their combination to produce a flexible and friendly use simulation model. Figure (1) explains the flow chart, which represents the simulation of vehicle behavior at on ramp and the adopted logic to be merged into the freeway link. Flow chart also reflects the main structure of the simulation model. While Figure (2) explains the flow chart for the complete process of simulating vehicles in the freeway and their behavior when attempting to exit from off ramp or from the freeway segment [3].

1008 Development of Freeway Weaving Areas Microsimulation Model (FWASIM)

Figure 1. The logic of on-ramp vehicle simulation


Figure 2. The logic used for freeway vehicle simulation

5. Car-following Logic The car-following process is important to simulate the

traffic flow, analyze the formation mechanism of traffic congestion, and manage the alternative proposals [13]. The car-following process takes place when “a driver follows a lead vehicle and tries to maintain distance and relative speed within an acceptable range”.

Sultan et al. conducted a research to investigate whether

drivers are able to use information on the acceleration or deceleration of the lead vehicle during the car-following process. The authors collected field data for car-following process using an instrumented vehicle. A strong evidence was concluded that the drivers are able to realize the lead vehicle’s acceleration or deceleration [11].

The car-following process in FWASIM was considered when vehicles are at a distance of (60m) or less. This value was obtained from the observed results. The maximum


distance considered for car following logic is the product of the average observed preferred headway and the maximum observed speed increased by 10%. The increment is attributed to the fact that with the video recording technique, it is hard to get an accurate data representing the real behavior due to the fixed installation of the camera that will not cover all driver behavior diversity.

ILLISIM proposed a distance of 76m or less between the lead and follow vehicles for car following logic [5]. Herman and potts observed that driver’s behavior is not affected when the spacing between vehicles is greater than 61m in car-following [4].

In car-following process, drivers try to adjust their speed to keep a separation equal to their desired spacing. Desired spacing is the product of the speed of the follower vehicle and preferred headway. Preferred headway is the time a driver has, during steady state car following and represents the driver’s ability to develop the same amount of deceleration as the lead vehicle in case the leader breaks [6].

The main parameters that affect driver behavior in car following process are the desired spacing and the relative speeds of vehicles. Vehicles accelerate, decelerate or maintain speed depending on their desired spacing and relative speeds.

Three cases of leader and follower vehicles are considered at the simulation model: 1. When the speed of the follower vehicles is less than

their desired speed, then they accelerate to reach their desired speed;

2. When spacing is less than the desired, vehicles decelerate if the leader speed is equal to or less than the follower speed. For the same case, vehicles coast when the speed of the leader is greater than the follower speed; and

3. When the spacing is greater than the desired spacing of the follower vehicle and its speed is less than its desired speed, in this case vehicles adopt acceleration maneuver.

6. Lane Changes Maneuver Lane changes are classified as either mandatory Lane

Change (MLC), for example, a required lane change, or discretionary Lane Change (DLC) as in case of a driver trying to improve his driving conditions. Lane change process was simulated according to the following:

Multilane highways (up to six lanes in this simulation model) are scanned and processed in each time step (one second) from left to the right and then from the right to the left for every two adjacent lanes. Lane change process is randomly occurred for each case depending on simulated traffic conditions.

The successive case was then checked if it fits any of the four main cases that frequently occur and simulated to represent the real site situations. The four cases were categorized based on the traffic availability in the target lane. The four main cases are graphically illustrated in Figure (3).

Lane changing maneuver under both MLC and DLC types was applied in the current simulation model as a sequence of four steps: 1. Driver decision to apply a lane change, in case of the

subject vehicle speed is less than its desired speed and it is a weaving vehicle type,

2. Choice of a target lane, this depend on the available gaps and also depend on the vehicle weaving type,

3. Acceptance of lead and lag gaps, and 4. Performing the lane change maneuver.

Figure 3. The four main lane change cases


7. Modeling Segment Geometry

7.1. Modeling On-ramp Geometry

The on-ramp in this model is considered consisting of one lane. This lane is assumed sufficient to allow for the passage of only one row of vehicles in one direction. The on-ramp lane was assumed to meet the highway link by at start of the acceleration lane. The meeting point represents the on-ramp vehicle generation. It is considered as the origin of the simulated vehicle on the On-ramp. The weaving type determines the destination of each vehicle.

7.2. Modeling Link Geometry

The modeled highway link or the main road of freeway consists of up to six lanes in the simulation model indicated by numbers starting from one for the far side lane. This number will remain as a label for each vehicle entering the simulated area. To achieve flexibility in modeling a range of possible freeway layouts, the number of lanes is specified to the simulation model through input.

The vehicle generation for these lanes starts from the beginning of the link at a point just before reaching the on-ramp nose by a given distance specified to the simulation model by input.

The segment length computation starts from the vehicle generation point (origin point) which includes the followings:

1. The nose length, which is the distance between the origin point and the meeting point of on-ramp with the highway link;

2. The acceleration lane length (auxiliary lane), is used by the on-ramp vehicle to merge.

3. The weaving area length, which is the distance from the nose to the off-ramp position, by which the acceleration and the deceleration lane lengths are involved.

4. The sign position, is an implicitly distance within the weaving area length needed for the exit sign to be installed a distance before the off-ramp (exit position); and

5. The deceleration lane length that is the lane used by the exit vehicles before leaving the freeway through the off-ramp.

The above lengths were specified to the simulation model by input. The other geometric parameters such as gradient and curvature were not considered at this stage of the model development. Figure (4) represents typical cross section showing the highway geometric parameters.

7.3. Modeling Off-ramp Geometry

The off-ramp geometry is assumed to consist of one lane. This configuration allows for movement of raw of vehicles in the highway exit direction. During the simulation model input stage, the user should specify a number equal to (1) to represent the number of off-ramp lanes. The off-ramp lane is assumed to meet the highway link at the end of the deceleration lane.

Figure 4. Typical proposed freeway segment cross section


7.4. Modeling Traffic Data

Microscopic models permit measurement of a vast range of traffic features and allow many traffic management strategies to be tested. Because the developed model is microscopic type, therefore, the majority of the important and effective vehicle attributes and driver characteristics are modeled and specified to the model by input.

In general, traffic characteristics may be classified into three main categories; 1. Static characteristics include physical and fixed

vehicle attributes, such as size and type. 2. Dynamic characteristics, which represent the degree

of alert of a driver and his response as he may face an incident. and

3. Kinematic characteristics represent the vehicle performance and driver characteristics, such as acceleration and deceleration rate.

The traffic data which were modeled in the current simulation model represent collection of the above three categories.

An important assumption made in this study is that the different behavioral characteristics, such as desired speed, acceleration rate, critical lags and gaps, etc. of a vehicle-driver are generated independently. In the real world situation, it is more probable that a driver with a high desired speed will accelerate and decelerate faster, and has a smaller critical lag and gap than a driver with a lower desired speed.

Vehicle attributes and driver features which were modeled are described hereafter [3]; Type and arrival time of the generated vehicle. The vehicle movement type, if it is weaving or

non-weaving vehicle. Vehicle acceleration rate. and desired speed. Driver preferred headway, brake reaction time, and

accepted gap. Spacing and desired spacing. Vehicle label. Entry lane number

7.5. Vehicle Arrivals

Vehicle arrivals are provided by means of vehicle generators considered at a distance on freeway segment before on ramp nose. This distance is specified to the model by input. Numbers are generating from uniform distribution of an interval (0, 1). The model using the transformation given below calculates times between successive vehicle arrivals; 1. In case of negative exponential distribution

𝑡𝑡 = log(𝑅𝑅𝑅𝑅𝑅𝑅)𝑞𝑞

(1)

2. In case of shifted negative exponential distribution

𝑡𝑡 = 1 − log (𝑅𝑅𝑅𝑅𝑅𝑅)[�1𝑞𝑞� − 1] (2)

Where, is the generated time interval in seconds,

is a random number distributed uniformly in the range (0,1), and

is the vehicle flow in veh/sec.

7.6. Vehicle Desired Speed

The desired speed of a driver is the speed on which he/she try to maintain. The following important variables are affecting the desired speed [1]: Highway geometry. The quality of pavement surface. Weather conditions. The limited speed of the specific highway section. Density of traffic in front of the vehicle. Vehicles speed in front of the simulated vehicle. Traffic composition. type of the vehicle, and The driver characteristics.

Each simulated vehicle assigns desired speed generated from a normal distribution. The values of the normal distribution, which are; mean, standard deviation (STD), minimum, and maximum values are specified during the input stage. In specifying the upper and lower limit of the desired speed, bounds are set to the distribution curve. The technique of lane specific values for the desired speed is considered.

It is also assumed that drivers moving on the far side lane have low range of variation that is low standard of deviation. By contrast, it was assumed a high range of variation of desired speed for drivers moving on the near side lane.

7.7. Type of Vehicle Movement (Weaving and Non-weaving Vehicles)

According to their movement type, the generated vehicles are either weaving or non-weaving type. Based on the comparison with a random number generated from the uniform distribution, the vehicle is considered either weaving or non-weaving.

To achieve the logic in the developed simulation model, the proportions of weaving and non-weaving vehicles should be provided during the data input stage. One of the outputs of this followed logic is the determination of vehicle destinations. This is because, vehicles originating from highway link and considered as weaving vehicles then their destination must be the off-ramp exit. Similarly, weaving vehicles originating from on-ramp will continue their movement with the non-weaving vehicles originated from the highway link. This method is applicable for both vehicles generated from on-ramp and those from highway link.

tRnd

q


7.8. Traffic Composition

The traffic composition has a substantial effect on the operating characteristics. Values of traffic composition for highway flow and on-ramp flow are held in a cumulative form. In the simulation model, whenever vehicle is generated, a random fraction of unity is generated according to a uniform distribution. Generated random number is divided according to the cumulative form into parts. Each part represents vehicle type proportion. If vehicle type proportions are not supplied, the program applies default values given in Table (1). The default values were concluded from the average observed values during the study period conducted on different highway sites at Baghdad city.

Table 1. Default vehicle type proportions

Vehicle type Passenger cars Buses Trucks Others

Proportion 0.90 0.03 0.06 0.01

7.9. Acceleration and Deceleration Rate

The acceleration rate depends mainly on vehicle capability and performance. The simulation model adopted Gipps acceleration model. Equation (3) below explains Gipps model [8].

(3)

Where, is the maximum speed to which vehicle can

accelerate, is the generated acceleration rate,

is the time step in seconds, is the speed of the subject vehicle, and is the desired speed of the subject vehicle.

Normal acceleration rate is drawn from a normal distribution generated randomly for each simulated vehicle. The observed values for acceleration and deceleration rates are shown in Table (2).

Table 2. Parameters of normal acceleration rate

Rate Mean m/s2 STD Minm

m/s2 Maxmm/s2

Acceleration 2.69 1.70 0.7 5.2

Deceleration 2.66 1.45 0.85 5.0

7.10. Spacing Gap

When vehicle is generated, each driver assigns a critical gap drawn from a normal distribution. In order to compute the available spacing used in the car following logic, the gap value is transformed into distance (meters) and supplied during the input stage.

7.11. Time Preferred Headway Modeling

When a vehicle is generated, each driver assigns a preferred headway drawn from a normal distribution. The value of preferred headway is used to calculate the desired spacing used for car following logic adopted in the developed simulation model.

7.12. Modeling of Break Reaction Time

Brake reaction times can be expected from drivers who have to brake suddenly and unexpectedly. The sudden brake results in a time delay in a driver’s response, or in other means, it is the response lag. It includes both the perception and reaction times. Identification of these two times separately at the observed data is difficult, therefore the break reaction time term represents the summation of the two. When a vehicle is generated during the model simulation process, each driver is assigned a value of break reaction time drawn from a normal distribution.

8. Simulation Model Verification and Validation

The simulation model verification and validation test process can be split into three stage [2]: 1. Software testing often called model verification, 2. Assessment of overall performance of the model

validation, and 3. Hypothesis testing and modification, called model

calibration.

8.1. Model Verification

The process of model verification is to determine if the logic of model listing as described by the model developer is compatible with the computer code, and to check if the input data produces the desired and accurate results (output data) in terms of magnitude and direction [10].

The verification process for the current simulation model is made in two sequential steps. The first step involves compiling the program, running it for error-free and with only the necessary mathematical approximation. The current computer model was written with visual c++language. This language technique has debugging facility, which allows the execution of the program to be controlled so that the developer can monitor specific locations, variables, change of array dimensions etc., and check the sequence of program control. After tracking down the mistakes, the source program was edited to produce a new version. The procedure was repeated as long as an error is detected and corrected.

After establishing the internal correctness of the model, a number of tests were carried out to establish a measure of confidence in the model performance, which represents the second step of the verification process. Selection of the values of input parameters is involved through the test step.

21

)025.0(*)1(***5.2dd V

VVV

m TaccVV +−+=

mV

accTV

dV


These values enclose the expected domain of application of this model.

Verification process can be performed depending on data rather than of field data. However, considering of field data will ensure that the verification is achieved for some input parameters, which are similar with field conditions.

8.2. Simulation Model Validation

Analytical validation and field validation processes were conducted to test the validity of FWASIM. These two processes are fully explained in the following sections;

8.2.1. Analytical validation

A simple hypothetical freeway weaving section was conducted to validate FWASIM. Tests were based on comparison of FWASIM output with the output of VISSIM. The selection of test was made to consider the important factors, which may affect the vehicle behavior for a given freeway, segment configuration. The HCS2000 software is used to calculate the capacity of the weaving segment.

Proposed weaving sections were specified to be examined under different vehicle parameters and various flow conditions with different weaving area configurations. The following is an example for one of the proposed sections explaining how the simulation model was analytically validated. The objective of this test is to examine the model performance by simulating the behavior of traffic stream through a weaving section and then compare the results with that resulted when the same

proposed weaving section is simulated by VISSIM. The geometric layout of the proposed weaving section

and the percentage of the weaving flow are shown in the Figures (5) and (6) respectively. The weaving segment capacity was 4380 veh/h as computed by HCS2000 program for the same prevailing conditions.

Figure 5. The geometric layout of the weaving section

Figure 6. the flow-weaving diagram

The average desired speed of vehicles in the weaving section was chosen to be the measure of effectiveness parameter to compare the results. Figures (7) shows the VISSIM schematic of test site.

Figure 7. VISSIM schematic of proposed site


The desired speed FWASIM simulation results are compared with that resulted by VISSIM. Figures (8) illustrates and compares the results with the corresponding traffic volume starting from 500 veh/h to the determined section’s capacity.

Figure 8. Average desired speed comparison results

Figure (8) indicates a tendency for the simulation model to overestimate traffic speed near the section’s capacity. This simulation model behavior is attributed to the FWASIM input method of driver behavior that represents the gap, brake reaction time, and the preferred headway. These attributes are not assigned during the VISSIM input stage. Figure (9) explains the FWASIM input for driver and vehicle attributes.

Figure 9. FWASIM traffic attribute input

Because of the simulation modeling of FWASIM was

built based on the observed field data, then the difference in outputs of traffic parameter values will be attributed to the great varieties in driver behavior, vehicle characteristics. Driver decision plays an important role in the position and the speed of each vehicle, which is also influenced by external factors relating to the roadway geometry and traffic interaction. Therefore, the conclusion for the above section is that the simulation model is may considered analytically validated.

8.2.2. Simulation model field validation

Model validation considers, as “the process of determining to what extent the model’s underlying fundamental rules and relationships are able to adequately capture the targeted behavior, as specified within the relevant theory and as demonstrated by field data”. In other words, can the driver’s behavior or traffic feature rules used by the model produce the relative traffic performance such as capacities, densities, and the effect of weaving [10].

Consequently, it is necessary to compare the simulated results from the model with the observed data from survey sites. Validation is the process checking the overall model-predicted traffic performance for a facility against the observed field data of traffic performance not used in the calibration stage [7].

Travel time (TT) was selected as a sensitive traffic parameter to be used for simulation model validation purpose. TT is defined as “the time difference between the time of vehicle leaving the weaving area and its initial time by which vehicle entering that area”. Measurement of TT may implicitly reflect vehicle delay through highway section. For the observed TT calculation, data were collected from different sites other than that used in the simulation model development stages. The observed vehicle TT was classified into four categories according to origin-destination concept. Each category represents one type of vehicle movement. Table (3) shows these categories and their corresponding vehicle movement type.

Table 3. Different categories with their vehicle movement type.

TT category Movement type

Origin destination

1 Link Link

2 Link Off-ramp

3 On-ramp Link

4 On-ramp Off-ramp

Computer programs were used as an aid tools to collect and abstract data from videotape. Their outputs were processed and analyzed to compute average vehicle TT for the different categories. The observed traffic parameter values were specified to the simulation model as an input. Table (4) shows these observed parameters with their statistical values. The observed passenger car percentage was 90%.


Table 4. Statistical values for observed input parameters

Parameter Mean STD Minm Maxm Speed, km/h 75 23 40 135

Acc. rate, m/s2 2.70 1.70 0.75 5.2 Dec. rate, m/s2 2.60 1.45 0.85 5.0

Preferred headway, sec. 1.40 0.40 1.0 2.1

Break reaction time, sec. 1.17 0.26 0.60 2.10

The simulation model was run several times with the observed values for each session of the collected data to

obtain the simulated average TT for each category (origin-destination type). The simulated vehicular TT and the observed results for all sessions are presented in Table (5).

The comparison of the simulated and observed results is graphically illustrated in Figure (10). The line x=y has been superimposed in the plot to facilitate comparison. The mean for observed and simulated TT are not matching exactly. However, they are close enough to establish a level of confidence that the model is capable of simulating a freeway weaving area operation.

Table 5. Observed and simulated values of TT

Observed TT, sec. Simulated TT, sec.

cat.1 cat.2 cat.3 cat.4 cat.1 cat.2 cat.3 cat.4

14.0 14.5 15.0 14.5 14.5 15.0 14.8 15.0

13.5 13.0 14.0 13.5 14.0 13.5 14.2 14.0

12.5 12.5 13.5 13.0 12.0 17.0 13.8 13.5

15.5 15.0 18.6 16.4 16.0 15.8 16.2 16.5

16.7 17.0 19.5 18.4 15.5 17.5 17.6 17.5

16.0 15.5 18.0 17.6 15.2 15.4 17.5 17.0

17.5 16.5 14.5 15.0 16.0 17.5 15.5 15.5

17.0 18.5 16.0 15.5 16.5 16.3 16.5 15.5

18.0 18.0 17.5 16.5 19.0 18.5 16.8 17.0

19.0 18.5 15.5 16.0 18.2 18.4 17.2 17.0

19.0 19.5 16.5 17.0 18.0 18.5 16.0 18.0

17.5 17.0 15.5 15.0 16.5 16.2 16.5 16.0

18.6 18.5 17.5 17.0 18.0 17.6 16.5 16.5

19.5 19.0 18.0 18.0 19.0 18.5 17.5 17.5

20.0 20.5 19.5 19.0 19.0 21.0 18.7 18.8

21.0 19.5 18.0 17.5 20.0 20.5 18.5 18.0

22.5 21.5 19.5 18.5 22.0 22.0 20.4 18.8

25.0 24.5 24.5 23.5 24.0 24.2 23.8 24.2

28.5 27.0 26.5 26.0 18.8 28.0 26.5 25.5

30.5 31.0 28.5 29.0 29.2 30.5 30.0 28.8

32.0 31.5 30.0 29.0 31.8 31.0 31.0 29.5

35.0 34.0 33.5 32.5 34.5 34.6 33.0 33.0

36.0 34.5 35.0 34.5 35.7 35.5 34.5 33.8

36.5 37.5 38.0 33.0 38.0 39.5 36.5 39.5


Figure 10. Part A to D Comparison between observed and simulated TT for all movement type

T-test was used to validate the results. The observed and simulated average mean values were calculated and found to be (21.08) and (21.04) seconds respectively. At the 5% level of significance and 23 degrees of freedom, the calculated t value is (0.027).

The corresponding tabulated t value, that is, the critical t is (1.71) which is higher than the calculated t. This has the implication that there is no reason at 95% level of significance, to reject the hypothesis that the observed results may be represented by the simulated results. This implies that the results are statistically significant and the model provides reasonably accurate measures of effectiveness for the validated range of input data.

9. Results Analytical validation is conducted by specifying

proposed weaving sections to be examined by FWASIM and VISSIM under various traffic features, flow conditions, and different weaving area configurations. Their results of comparison showed an acceptable agreement. However, results indicated a tendency for the simulation model to overestimate traffic speed near the section’s capacity. This behavior is attributed to the FWASIM input method of driver behavior that represents the gap, brake reaction time, and the preferred headway, which are not assigned during the VISSIM input stage.

Field validation produced that the mean for observed and simulated TT are not matching exactly. However, they are close enough to establish a level of confidence that FWASIM is capable of simulating a freeway weaving area operation.

10. Conclusions This study focused on developing microsimulation

program to measure the performance of the weaving sections at the freeway, where the traffic conflict occur due to the weaving process. The followings can be concluded; 1. Microscopic traffic simulation model is the suitable

tool to develop vast numbers of online traffic management strategies instead of field testing solutions, which are costly and cumbersome.

2. FWASIM output for predicting traffic stream models (speed-flow-density relationship) at weaving sections was agreed with that predicted by VISSIM program. However, there was a tendency for the simulation model to overestimate the traffic speed near the section capacity. The reason was attributed to the difference in driver decisions and traffic charactrisitics adopted by the two softwares.

3. FWASIM could be applied to analyze and design highway sections with a range of geometric configurations under different local traffic conditions.


11. Recommendation It is recommended to calibrate FWASIM for more

sensetive input traffic parameters, in case of applying FWASIM in an area other than the area of study, which is the Republic of Iraq, Baghdad city.

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Lane Changing Behavior. Ph.D, Massachusetts Institute of Technology, USA, 1999.

[2] Ali, Al Neami, and Alkubaisi Mahdi. Study of Vehicle Behavior at Signal Controlled Junctions. College of Engineerin, University of Baghdad Journal of Engineering,Vol. 6 No. 4, 2000.

[3] Alkubaisi, Mehdi. Simulation Modeling of Traffic Behavior at Speed Change Lanes. Ph.D, University of Baghdad 2004.

[4] Aycin, M, and R Benekohal. Linear Acceleration Car-Following Model Development and Validation. Transportation Research Record: Journal of the Transportation Research Board, no. 1644: 10–19, 1998.

[5] Bham, Ghulam H, and Rahim F Benekohal. Illisim, a fast high fidelity traffic simulation model based on cellular automata and car-following concepts. Transportation Research Board 80th Annual Meeting 2001.

[6] Bham, Ghulam H Benekohal, Rahim F. A High Fidelity Traffic Simulation Model Based on Cellular Automata and Car-Following Concepts. Transportation Research Part C:

Emerging Technologies 12 (1): 1–32, 2004.

[7] Division, VDOT traffic Transportation. VDOT Vissim User Guide Version 2.0, no. January 2020.

[8] Jimenez, T, P Mussi, and G Siegel. A Road Traffic Simulator: Car-Following and Lane-Changing. European Simulation Multiconference May 2000 (Lc): 241–45, 2000.

[9] Koppula, Nanditha, and Antonio A Trani. A Comparative Analysis of Weaving Areas in HCM , A Comparative Analysis of the Weaving Areas in HCM, TRANSIMS, CORSIM, VISSIM and INTEGRATION. Integration The Vlsi Journal, no. April 2002.

[10] Rakha, Hesham, Bruce Hellinga, Michel Van Aerde, and William Perez. Systematic Verification, Validation and Calibration of Traffic Simulation Models. In 75th Annual Meeting of the Transportation Research Board, Washington, DC. Citeseer 1996.

[11] Sultan, Beshr, Mark Brackstone, and Mike McDonald. Drivers’ Use of Deceleration and Acceleration Information in Car-Following Process. Transportation Research Record: Journal of the Transportation Research Board, no. 1883: 31–39, 2004.

[12] S. Kim, W. Suh and J. Kim, Traffic Simulation Software: Traffic Flow Characteristics in CORSIM. International Conference on Information Science & Applications (ICISA), Seoul, 2014, pp. 1-3, doi: 10.1109/ICISA.2014.6847475.

[13] Zhang, Yong, Ping Ni, Minwei Li, Hao Liu, and Baocai Yin. A New Car-Following Model Considering Driving Characteristics and Preceding Vehicle’s Acceleration. Journal of Advanced Transportation. https://doi.org/10.1155/2017/2437539, 2017.


Analysis of Interior Design of Restaurants with Reference to Ambience and Customer Gratification

Sadia Farooq1, Faiza Zubair2, Mohammad Arif Kamal3,*

1Department of Science, University of Home Economics, Pakistan 2Department of Family and Consumer Sciences, University of Home Economics, Pakistan

3Architecture Section, Aligarh Muslim University, India


Cite This Paper in the following Citation Styles (a): [1] Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal , "Analysis of Interior Design of Restaurants with Reference to Ambience and Customer Gratification," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1019 - 1027, 2020. DOI: 10.13189/cea.2020.080528.

(b): Sadia Farooq, Faiza Zubair, Mohammad Arif Kamal (2020). Analysis of Interior Design of Restaurants with Reference to Ambience and Customer Gratification. Civil Engineering and Architecture, 8(5), 1019 - 1027. DOI: 10.13189/cea.2020.080528.


Abstract This study introduces an investigation into the effect of ambience on customer’s gratification at the restaurants where numerous regular alterations in color, layout, light, aroma, cooling temperature, décor etc. are being done. Restaurateurs’ goal is always to generate income for which they do alterations in their buildings’ interiors. Relationship between customer gratification and three ambiences’ features color, light and cooling is observed in two restaurants, named, Lahore View and Jasmine restaurants situated in Shalimar Tower Hotel, Lahore. A sample of 354 customers from these two restaurants was taken. The correlation coefficient between the income and dine in frequency was found to be highly significant leading to the conclusion that as income increases the dining frequency also increased. Associations between customer’s satisfaction and demographic feature like income and gender were also studied, which were found statistically insignificant. To analyze the impact of ambient color, light and cooling on customer’s gratification, a binary logistic regression model is applied with color, light and cooling factors as predictors. The regression was found to be highly significant with significant model parameters leading to the conclusion that color, cooling and lightning improvements can help in increasing customer’s satisfaction which will eventually lead to the increase revenue generation.

Keywords Interior Design, Restaurants, Ambience, Customer Gratification

1. IntroductionThe Customer gratification is for the most part

associated with service feature in the eatery business [1] instead of worrying on ambience of the spot. The restaurateurs have a demand to clarify this gap in researches, to analyze the impact of ambience on customers’ gratification because most of the people do not consider ambience a factor to increase revenue even it is. The studies in relation to customer gratification, ambience and revenue are limited [2]. Ambience can include a wide range of features such as exterior and interior layout, color, light, temperature, music, odor [3][4][5][6][7][8]. Most of researchers like Oliver, Kivela, Jordaan, Prinsloo, Choi, Chu and Park agreed that customer gratification is important to restaurateurs because patron return depends on it, repetition in discussions, recommendations and revenue generation. The dimensions of ambient features, color, light, and cooling were researched and discussed, separately [9][10][11][12][13].

The Restaurateurs may stress on continually changing the design of the restaurants including colors, light, cooling, and employee’s style but the impact of the alterations on ultimate users is also not extensively or entirely documented [14]. There were a number of restaurants in Lahore which are struggling to compete in the market, they

1020 Analysis of Interior Design of Restaurants with Reference to Ambience and Customer Gratification

not only stress on the quality of food but also prefer the ambience to attract customers. The two restaurants present in Shalimar Tower hotel, were selected, named, Jasmine restaurant and Lahore View restaurant. The reason to select the restaurants was the alterations were regularly being made in the interiors of the restaurants but not being analyzed. The objectives were set to find out the connection between customer gratification and ambient factors such as color, light and cooling, given below: To analyze the impact of demographic characteristics

on customer’s satisfaction. To find out the relationship between color, cooling

and lights in the restaurants on customers’ gratification.

2. Literature Review The literature is all about the ambient features and their

linkage to the customer gratification.

2.1. Customer Gratification and Ambient Conditions

The customer gratification is a relationship between professional benefits and administrative strategies to fulfil customer demands. Increasing significant level of client satisfaction is critical to organizations in light of the fact that fulfilled clients and to utilize a wide scope of administration [15][16][17][18]. Customers are the sole explanation behind the presence of business foundations [19]. Lim suggests that, clients’ final gratification can have critical impact associated with ambient conditions inside the eating place [20]. Researchers have distinguished ambient settings as a condition that influence impression of human reactions related to surroundings [21][22]. Surrounding conditions envelop a variety of foundation qualities of the earth, for example, design, temperature, color, light, commotion, music, and aroma [3][4][5].

2.2. Customer Gratification and Ambient Color

The utilization of appropriate colors in interiors of a restaurant can make the place practically feasible and acceptable to the customer and can impact of restaurant incomings [23]. Bright colors, in general impress and arouse emotions while deep warm and casual light shades appear to advance leisure and repose [24]. The hues are differentiated into hot and light colors like red, orange and yellow are considered to be hot while cool colors are green, blue and violet. Hot colors show people, the imprint of hot agreeable conditions [11]. The cool colors also, make comfortable places which contribute in customer appreciation [23].

2.3. Customer Gratification and Ambient Light

A restaurant, appropriate light is required to look at the food at its best by the customer. The conclusion is that all efforts are for the customer to be satisfied [25][26]. Therefore, the restaurant required to light each table individually, to create its own ambience [27]. Light can make the place cool and calm for the enjoyment of the services and experience. Customers speak more politely and delicately when lights are dim [28]. Light can be one of the most dominant physical features which influence the most in the restaurants [29]. Light is also the impression which a restaurateur wants to create [27]. The light can distinguish the place to have a unique experience than in any other place. The pioneer of the light research, Flynn, Hendrick, Spencer, Martyniuk, investigated the impact of light on customer feelings and attitude so that light will play a role as an ambient attribute [30][31][32].

2.4. Customer Gratification and Ambient Cooling

The challenge of maintaining a business includes diverse temperature and individuals' varying desires which must be understood and accomplished [26]. There are a lot of requirement in a restaurant such as proper ventilation, water purification, appropriate temperature etc. but the result must be in form of satisfied diners with appropriate ambience. The constant temperature can provide a consistent patron behavior [26]. Restaurateurs use air conditioning method to maintain the temperature of restaurant. The temperature imbalance can damage the overall impact of a restaurant because the customers would not like too hot or cold according to climate outside and can eventually damage the restaurant image. These outcomes in lost revenue, in this manner, the parity must be accomplished through cooling. Huang et al explored on the impacts of surrounding cooling on item inclinations and budgetary basic leadership. Results featured that agreeable encompassing cooling impact shopper inclination for similarity. Clients have no indistinguishable physical and enthusiastic marks, in this way, restaurateurs should locate a shared belief where the larger number is content. This can result in the loss of revenue or profit. The uniformity is required through constant temperature studied the effects of ambient low or required temperature to be preferred on items’ likeness and money decisions. The results highlighted that the constant temperature provides comfort to the customers and impact on their preferences. Customers are always not satisfied on one choice which seems difficult to achieve but restaurateurs must stress on the preferences of majority of the people [33].

3. Research Methodology The causal research design was studied to find out the

cause and effect relationship of customer gratification and ambience [34]. The population was the customers of all the restaurants who offer regular alterations in their interior


design along with food quality or service, to welcome and increase their customers and ultimately to increase revenue. Two restaurants, named, restaurant 1, Lahore View (Fig 1) and restaurant 2, Jasmine (Fig 2) situated in Shalimar Tower Hotel, Lahore were selected. The ambience which is showing interior elements, furniture, color scheme, lighting (Fig. 3,4,5,6) and even air conditioning unit is visible (Fig 2,6) in below given pictures. The technique used for the study was Simple Random Sampling Technique. The sample size was 354.

Figure 1. Restaurant 1 Furniture and Ambience

Figure 2. Restaurant 2 Furniture and Ambience

Figure 3. Restaurant 1 with Rope Lighting

Figure 4. Restaurant 2 with Chandeliers

Figure 5. Restaurant 1 in White Light

Figure 6. Restaurant 2 in White Lighting

Personally, administered closed ended questionnaires were given to assemble first hand data. The questionnaire was taken from Omar et al and Ayaz amendments were incorporated according to the study. Five-point Likert scales were chosen to measure constructs, customer gratification, c o l o r , light, and temperature [5] [6]. Each feature included four items. Statistical Package for Social Sciences (SPSS) version 16 was used to carry out the Analysis with these three basic hypotheses


1: Null hypothesis: There is no correlation between income and age of customers and dine in frequency

Alternative hypothesis/: There is significant correlation between income and age of customers and dine in frequency

2: Null hypothesis: There is no association between demographic characteristics (gender/income) and customer’s gratification

Alternative hypothesis: There is significant association between demographic characteristics (gender/income) and customer’s gratification.

3: Null hypothesis: Cooling, Color and Lightning in restaurant have no significant impact on customer’s gratification

Alternative hypothesis: Cooling, Color and Lightning in restaurant have significant impact on customer’s gratification

4. Data Analysis and Interpretations The data analysis is represented in tabular form, where

the customer gratification was dependent variable and color, light and cooling were independent variables. Some of the abbreviations are assigned to the constructs in tables, given below:

Customer Gratification = CG, Ambient Color= AC, Ambient Light= AL, Ambient Cooling=ACL

4.1. Reliability and Validity Test

The first step was to test the reliability and validity of the questionnaire, the value of Cronbach’s alpha and the reliability coefficients were obtained as under:

Table 1. Test for Reliability of Questionnaire

Constructs Cronbach’s coefficient

Average Variance Extracted

C G 0.757 0.853

Color 0.823 0.845

Light 0.780 0.723

Cooling 0.746 0.771

Table 1 indicates the value of Cronbach’s alpha for each construct which is greater than 0.7, so the questionnaire was found to be a reliable one.

Then validity of the questionnaire was tested. For construct validity the average variance extracted (AVE) from all constructs, exceeded the minimum criterion of 0.50 (table 1), formula was extracted from Hair et al [34].

Table 2 indicates the R value where (average variance extracted) AVE of gratification of customers and color were 0.812 and 0.845 respectively, which is evidently greater than the R2 value of these two constructs. Customer gratification and light has an AVE of 0.701 and 0.723 which is found to be greater than the R square. Customer

gratification and cooling has an AVE of 0.649 and 0.771 which is clearly higher than the value of their combined R square. Similarly, on pair wise comparisons, it can be easily seen that the AVE for the constructs is higher than the R square values of two constructs. This ensures that the questionnaire has discriminant validity.

Table 2. R square values of customer gratification, ambient color, light and cooling

Variables Customer Gratification AC AL AC

C G 1

A C 0.812 1

A L 0.701 0.449 1

A CL 0.649 0.456 0.278 1

5. Demographic Characteristics The sample of 354 customers had the following

demographic characteristics

Table 3. Gender Distribution of the Respondents

Gender Frequency Percentage (%)

Female 167 47.2

Male 187 52.8

Total 354 100.0

The table 3 is indicates that there were 47.2% males and 52.8% females in the sample, who participated as respondents.

Table 4. Income Distribution of the Respondents

Income Level Frequency Percentage (%)

Low income 20 5.6

Middle income 203 57.3

High Income 131 37.0

Total 354 100.0

‘The Table 4 indicates that 57.3% of the respondents were belonging to the middle-income group while 37% belonged to higher income and only 5.6% were from lower income group.

Table 5. Age Distribution of the Respondents

Age Level Frequency Percentage (%)

15-25 75 21.2

25-35 101 28.5

35-45 65 18.4

45-55 61 17.2

above 55 52 14.7

Total 354 100.0

The Table 5 indicates the age distribution of the


respondents. It can be seen that about 85% of the respondents were less than 55 years of age.

Correlations between dine in frequency, age and income are calculated to find out the relationship between them

Table 6. Correlations between Dine in Frequency, Age and Income

Age Income Dine in Frequency

Age

Pearson Correlation 1 -.007 .087

Sig. (2-tailed) .890 .102 N 354 354 354

Income

Pearson Correlation -.007 1 .540**

Sig. (2-tailed) .890 .000 N 354 354 354

Dine in Frequency

Pearson Correlation .087 .540** 1

Sig. (2-tailed) .102 .000 N 354 354 354

**. Correlation is significant at the 0.01 level (2-tailed).

The Table 6 indicates the value correlation coefficient between age and dine in frequency is 0.087 which is insignificant, concluding that there is no significant correlation between age and dine in frequency while the correlation between income and dine in frequency is 0.54 which is highly significant (p value=0.00) and positive concluding as the income increases, the dine in frequency also increases.

6. Test of Association Chi Square Test of Association is used to test the

association between the demographic factors and customers gratification.

6.1. Gender and Customers Satisfaction

H04: There is no association between gender and customer’s satisfaction

H4There is association between gender and customer’s satisfaction.

Table 7. Gender * satisfaction Cross Tabulation

Not Satisfied Satisfied Total

Female 36 131 167

Male 47 140 187

Total 83 271 354

The table 7 indicates the cross tabulation of gender and satisfaction. It can be seen that most respondents are satisfied and responses are homogeneously distributed between the two gender groups.

The table 8 is indicating the value of chi square =0.629 which is statistically insignificant (p=0.428>0.05) which indicates that customer’s satisfaction is not associated with the gender.

So the null hypothesis is accepted.

Table 8. Chi-Square Test

Value df Asymptotic

Sig. (2-sided)

Exact Sig.

(2-sided)

Exact Sig.

(1-sided) Pearson

Chi-Square .629a 1 .428

Continuity Correction

b .445 1 .505

a. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 39.16.

6.2. Income and Customers Satisfaction

Null Hypothesis: There is no association between income and customer’s satisfaction

Alternative Hypothesis: There is association between income and customer’s satisfaction.

Table 9. Income*satisfaction Cross Tabulation

Not Satisfied Satisfied Total Low income 5 15 20

Middle income 51 152 203 high Income 27 104 131

Total 83 271 354

The Table 9 indicates the cross tabulation of income and satisfaction. It can be seen that most respondents are satisfied and responses are distributed between the three income groups.

Table 10. Chi-Square Test

Value df Asymptotic Sig. (2-sided)

Pearson Chi-Square .932a 2 .628

Likelihood Ratio b .944 2 .624 a. 1 cells (16.7%) have expected count less than 5. The minimum expected count is 4.69.

The Table 10 indicates the value of chi square =0.932 which is statistically insignificant (p=0.628>0.05) which indicates that customer’s satisfaction is not associated with their income.

6.3. Binary Logistic Regression Model to analyze the Impact of Cooling, Lightning and Color Ambience on Customer’s Gratification as a Mode to Increase Revenue

The study targets at analyzing effect of cooling lights and color ambience on the customers’ satisfaction as a mode to increase revenue.

The model has three predictors color light and cooling ambience and one binary dependent variable Y= CG=Gratification/satisfaction where

Y=0 for unsatisfied customer Y=1 for satisfied customers


We denote p=P(Y=1) and assume a linear relationship between predictors and the log odds of the event y=1 (satisfaction), then the model can be written as

Where AC= Color, AL= Light ACL= Cooling 𝛽𝛽0,= Constant 𝛽𝛽1 ,𝛽𝛽2 𝑎𝑎𝑎𝑎𝑎𝑎 𝛽𝛽3 are the coefficients of C, L and CL

respectively. The odds can be obtained by exponentiation of the

log-Odds

The data were analyzed using SPSS and the following

results are obtained

Table 11. Omnibus Tests of Model Coefficients

Chi-square Df Sig.

Step 1 Step 83.244 3 .000

Block 83.244 3 .000

Model 83.244 3 .000

The table 11 indicates that the logit model is significant as p values are 0.00 which is less than the pre-assumed alpha 0.05.

Table 12. Model Summary

Step -2 Log likelihood

Cox & Snell R Square

Nagelkerke R Square

1 302.342a .210 .316 a. Estimation terminated at iteration number 5 because parameter estimates changed by less than .001.

The Table 12 indicates the summary of the model with Cox and Snell value or R square =.210 which is showing the model prediction also the Nagelkerke R square value of 0.316 which is also good for logit models.

The Table 13 indicates the results of the testing of the coefficients of the logistic regression model, it can be seen that all the three coefficients if cooling lightning and color are statistically significant. The constant is also found to be significant thus all the predictors have significant impact on the customer’s gratification

The logit model is given as

Table 13. Variables in the Equation

Value B S.E. Wald Df Sig. Exp(B)

Step 1a Color .369 .062 35.032 1 .000 1.447

Light .194 .086 5.070 1 .024 1.214

Cooling .153 .074 4.217 1 .040 .858

Constant -2.847 .555 26.274 1 .000 .058

a. Variable(s) entered on step 1: color, light, cooling.


Figure 1. Histogram predicted probabilities of customer satisfaction using the binary logistic model

6.4. Histogram of Predicted Probabilities

The histogram in Figure 1 shows the predicted probabilities of customer satisfaction using the binary logistic model for the sample of 354 observations is given below. The mean of the predicted probabilities is 0.7854 showing that the chances of customers gratification as predicted by the model are greater than 0.5.

7. Inferences and Analysis The impact of cooling, lighting and color ambience on

the customers gratification has been studied by applying a binary logistic model which is found to be significant and also the model parameters are significant showing that the three features have significant impact on customers gratification. Also, we have found the correlation between age and dine in frequency and income and dine in frequency. The correlation coefficient between the income and dine in frequency was highly significant and positive showing that dine in frequency increases with the increase in income. Association between customer’s satisfaction and age and association between customer’s satisfaction and gender was found to be statistically insignificant. It can be concluded that if the color, cooling and light ambience is improved, which will result in increase in customer’s satisfaction and can also help in generating increased revenues.

8. Discussion and Conclusions The research reveals around the customer gratification

and ambience conditions in restaurant industry. Overall, three ambient features color, light and cooling were considered which showed a positive relationship with customer gratification. The causal research design was adapted to find out the cause and effect relationship of customer gratification and ambience [35]. The restaurants of Shalimar Tower hotel were selected who had altered their ambience with food quality or service. The simple random sampling technique was used of a sample size of 354. Personally, administered closed ended questionnaires were given to assemble primary data. Five-point Likert scales were chosen to measure constructs, customer gratification, c o l o r , light, and temperature. Each feature included of four items. Regression analysis was applied on Statistical Package for Social Sciences (SPSS) Version 16. The coefficient of determination (R2) was applied to access the variability of customer gratification on the level of ambience features. The colors can also impact on customers’ mood and emotions in a restaurant setting because of the strong perception by humans to value colors [23][24]. The customer gratification and ambient color are most linked to consumers’ understanding that the human can perceive from the surroundings.

These results indicated that the administration at Shalimar restaurants should notice the application of colors in their place because customers give value to color. Light


is considered as most impacting element on human as one can only see food properly in light. The light is also considered as most significant encompassing variable as it permits the customers’ capacity to see the food in its most ideal manner. Along these lines, the executives ought to guarantee that when structuring the eatery light, each table ought to have its very own climate regarding the light as this prompt client satisfaction.

The three hypotheses were formulated to test the results so it was found there is significant correlation between income and age of customers and dine in frequency and there is significant association between demographic characteristics (gender/income) and customer’s gratification along that Cooling, Color and Lightning in restaurant have significant impact on customer’s gratification. Results showed that there is a positive relationship between customer gratification and light. Ayaz [6], Farooq and Ahmed [7], Farooq et al [8] Flynn et. Al [32] and [33] also concluded the similar results which supported the study that ambient light also positively impacts on customers’ feelings, behavior and gratification. These results suggest that Shalimar restaurants must stress more on light levels in the interiors. The opportunity to modify the temperature in the restaurants for customers raises its value. The study also showed that there is a positive connection between room cooling and client delight. This is in accordance with other researchers’ discoveries, Motoki, et al, Sharifi and Huang et al inferred that surrounding cooling decidedly influences client delight [25][26][34]. Generally, it is considered that the taste of food is the main factor to attract customers in the restaurant business but the ambience is also having strong influence on customer gratification [19][20]. Nonetheless, this exploration finding infers that restaurant supervisors can depend on surrounding conditions additionally as a reason for client gratification [21][22]. This examination approved that if interior ambience is improved it can also upgrade customer gratification in the restaurant experience. The results of binary regression were also significant and positive showing that improvement in color, lightning and cooling improves the overall customer’s gratification which eventually leads to the increase in revenue of restaurants [6][7][8].

In accordance with the above outcomes, it is recommended that restaurants ought to connect more into exercises, for example, upgrading or altering the light so as to light up the space more. In addition, the analyst suggests that the outlet ought to have appropriate color choice as this urges client to participate in drive purchasing. The temperature should be balanced to arrive at the ideal level through cooling.

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Evaluation of Mechanical and Durability Performance of Coir Pith Ash Blended Cement Concrete

Balagopal V, Viswanathan T. S*

Department of Structural and Geo-technical Engineering, School of Civil Engineering, Vellore Institute of Technology, Vellore, India

Received August 5, 2020; Revised September 22, 2020; Accepted October 19, 2020

Cite This Paper in the following Citation Styles (a): [1] Balagopal V, Viswanathan T.S , "Evaluation of Mechanical and Durability Performance of Coir Pith Ash Blended Cement Concrete," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1028 - 1038, 2020. DOI: 10.13189/cea.2020.080529.

(b): Balagopal V, Viswanathan T.S (2020). Evaluation of Mechanical and Durability Performance of Coir Pith Ash Blended Cement Concrete. Civil Engineering and Architecture, 8(5), 1028 - 1038. DOI: 10.13189/cea.2020.080529.


Abstract India is one of the prominent producers of coconuts in the world. Along with the desired products, many undesirable by-products are also generated from the coconut and coir industry. Among the various by-products, coir pith and short coir fibres are the major ones and are obtained during the extraction of long coconut fibres. Raw coir pith was heated in a metallic vessel at 450 oC to obtain coir pith ash. In this study, the impact of the presence of CPA as a supplementary cementitious material, on the various mechanical and durability parameters are taken into consideration. The various parameters considered for assessing the mechanical performance include compressive strength, split tensile strength, flexural strength and Ultrasonic pulse velocity. Water absorption and resistance to sulphuric acid environments were considered to evaluate the durability of CPA blended concrete. The resistance of CPA blended concrete against sulphuric acid environment was evaluated by considering the variation in weight, water absorption and percentage loss in compressive strength. Five concrete mixes were used for the study with CPA content ranging from 0% to 20%. Indian standard method of concrete mix design with water-cement ratio 0.45 was adopted. To understand the effect of change in water-cement ratio on the durability parameters of concrete, the study also considered other water-cement ratios like 0.40 and 0.50. Results indicated that the mechanical and durability performance improves when CPA is used as supplementary cementitious material. Also, the specimens with water-cement ratio 0.40 performed better than other ratios.

Keywords Concrete, Supplementary Cementitious

Materials, Coir Pith Ash, Durability, Acid Attack

1. IntroductionThe utilization of by-products from industrial and

agricultural sectors as supplementary cementitious materials (SCMs) are gaining popularity among numerous researchers across the globe. The use of SCMs not only improve the product quality of blended concrete but also reduces the cost and adverse impacts of concrete production. The most prominent and popular SCMs include fly ash, GGBS, metakaolin, sugarcane bagasse ash, wheat straw ash rice straw ash, rice husk ash, etc. [1-7]. These materials possess pozzolanic property due to the presence of amorphous silicon dioxide which undergoes secondary reaction with lime (Calcium hydroxide) present in the concrete matrix to form cementitious materials.

Concrete was considered to be a durable material and due to this consideration, concrete constructions were common even in areas of severe industrial pollution, harmful subsoil conditions and other circumstances where usage of alternate construction materials was not feasible. However, exposure conditions can have a tremendous impact on the life of concrete members. Though the durability of concrete can be assessed by compressive strength to some extent, it may not be entirely true that a strong concrete specimen or member is always durable since damage can occur due the harsh environmental conditions [8]. As per the definition given by the ACI committee, “Durability is the ability to resist weathering


action, chemical attack, abrasion, or any other process of deterioration” [9]. A concrete member can be considered durable if it maintains its initial characteristics when it is subjected to extremely harsh environments like acidic, chloride and sulphate environments. Deterioration occurs in concrete due to external and internal factors. The external factors include chemical attack and mechanical destruction induced by erosion, abrasion, impact and cavitation. Internal stresses caused by chemical reaction, porosity and permeability can be categorized as internal factors. Concrete is alkaline in nature and the acidic environment tends to impart neutralization reaction which reduces the alkalinity of concrete by reacting with hydration products to form calcium sulpho-aluminate (ettringite) and gypsum. These products possess low structural strength but require more space than the reagent compounds. Internal stresses are thus induced which results in the formation of cracks which eventually leads to reduction in strength [10]

The annual production of coconuts in India is nearly 11 megatonnes [11]. A spongy material known as coir pith is generated from coir processing unit which can be considered as a by-product. It is very interesting to note that coir pith constitutes 70% of the weight of coconut husk and the long fibres range only up to 30% [12]. Also, the rate of coir pith production ranges to 1.6 tonnes per 10000 coconuts [13]. The obtained coir pith is usually dumped in heaps and creates various environmental problems due to its slow degrading nature as well as the presence of phenolic compounds. Coir Pith ash (CPA) is obtained by burning dried coir pith ash at 400 oC for 4 hours. Then it was subjected to cooling for a duration of 6 hours. The obtained raw coir pith ash was sieved using 90-micron sieve. In a recent study, CPA passing through 200-micron sieve has been found to possess pozzolanic properties and the replacement of cement by CPA improved the mechanical performance of concrete [14]. However, the durability performance studies of CPA blended concrete were not carried out. Therefore, the research aims to assess the performance of binary blended cement concrete containing CPA passing through 90 microns by considering mechanical and durability parameters.

2. Materials The materials used for the research included cement,

fine aggregate, coarse aggregate and CPA. The cement used in the study fulfilled the requirements mentioned in IS 12269:2013 [15]. The standard consistency and specific gravity were found to be 36.75% and 3.15 respectively. Both initial and final setting time of cement were found out and the values were 77 minutes and 320 minutes respectively. Fine aggregate with used was natural river sand with a specific gravity of 2.67. The specific gravity of coarse aggregate was 2.70. Fineness modulus and specify gravity of coarse aggregates were found to be 7.22 and 0.81

respectively. The coir pith ash (CPA) used for the study was prepared by heating coir pith at 400oC for 4 hours. Fig. 1 and Fig. 2 show the Coir pith and Coir pith ash respectively. The details of various chemical components of CPA are shown in table 1.

Figure 1. Coir Pith

Figure 2. Coir pith ash

Table 1. Chemical Composition of OPC & CPA

Composition OPC (%) [16] CPA (%)

CaO 60-67 14.40

SiO2 17-25 46.85

Al2O3 3.0-8.0 1.76

Fe2O3 0.5-6.0 4.34

MgO 0.1-4.0 2.84

SO3 1.3-3.0 -

LOI - 7.24

1030 Evaluation of Mechanical and Durability Performance of Coir Pith Ash Blended Cement Concrete

Table 2. Compositions of Various Mixes

Mix No CPA % CPA (Kg)

Cement (Kg)

Fine Aggregate (Kg)

Coarse Aggregate (Kg)

Water (Ltr)

CM 0 % 0 438.13 655.72 1130.29 197.15

CC05 5 % 21.92 416.23 655.72 1130.29 197.15

CC10 10 % 43.81 394.32 655.72 1130.29 197.15

CC15 15 % 65.72 372.41 655.72 1130.29 197.15

CC20 20 % 87.63 350.51 655.72 1130.29 197.15

The Indian standard method of mix design of concrete was carried out and the water-cement ratio adopted was 0.45 [16]. While carrying out durability studies, water-cement ratios of 0.40 and 0.50 were also taken into consideration to understand the effect of water-cement ratio on durability performance. The cement was replaced by CPA up to 20 %.

The mix proportions are denoted by the following representations

CM – 0% CPA & 100% Cement. CC05 - 5 % CPA & 95% Cement CC10 - 10 % CPA & 90% Cement CC15 - 15 % CPA & 85% Cement CC20 - 20 % CPA & 80% Cement Table 2 shows the composition of various mixes used for

the research.

3. Methods

3.1. Compressive Strength Test

Cube specimens of 100 mm size were cast as per IS 516:1959 [17]. The specimens were then placed at room temperature of 27 ± 5 °C for 24 hours. The compressive strength test using the compression testing machine was carried out at various curing ages of 7, 28, 56 and 90 days. The capacity of the machine was 2000 kN and a pace rate adopted was 2.3kN/s

3.2. Split Tensile Strength Test

To find the split tensile strength, cylindrical concrete specimens of 100 mm diameter and 200 mm height were tested at 7, 28 and 90 days as per IS 5816-1999 [18]. Water curing method was adopted.

3.3. Flexural Strength Test

Flexural strength denotes the resistance against bending and was found out by conducting flexural strength test as per IS 516:1959 [17]. The load was applied until failure to concrete beam specimens of dimension 100 x 100 x 500 mm and the peak loads were noted. Three-point loading condition was used and the span length of the specimens was 500 mm.

3.4. Ultra Sonic Pulse Velocity Test

There are wide variety of non-destructive testing (NDT) methods which aim to test the specimens without destructing it. Ultra-sonic pulse velocity (UPV) method is one of the prominent NDT methods and is carried out mainly to assess the uniformity and relative quality of existing structures and specimens. The test was carried out with reference to IS 13311 (Part 1): 1992 [19]. The tests were conducted on day 7, 28, 56 and 90 after casting of specimens. IS 13311 (Part 1): 1992 classifies concrete based on the value of UPV and is shown in table 3. Various parameters of concrete quality like uniformity, absence of cracks, honeycombing, and segregation and other internal flaws in a particular specimen may be assessed by finding its UPV and comparing it with the specifications given in Table 3.

Table 3. Grading of Concrete based on UPV

PULSE VELOCITY CONCRETE QUALITY GRADING

Above 4.5 Km/S Excellent

3.5- 4.5 Km/S Good

3.0 – 3.5 Km/S Medium

Below 3.0 Km/S Doubtful

3.5. Water Absorption Test

Water absorption at 28 days and 90 days were determined as per American Society for Testing and Materials [20]. The concrete cubes of 100 mm were the specimens. After providing curing for the required number of curing days, the specimens were kept in an electric oven for 3 days at 60 oC and then allowed to cool to normal room temperature for 24 hours. The weight W1 was then taken. After that, the cubes were submerged in water in such a way that 50 mm water was maintained above the cubes. After a duration of 48 hours, the specimens were taken out from the water and placed on a dry cloth for 1 minute so that the water was allowed to drain. The weight of the specimen was noted immediately after that (W2). Water absorption was then calculated and was expressed in percentage.

Water Absorption = ((W2 – W1) / W1) x 100

The water absorption of CPA blended concrete was compared with those of control specimens to analyze the


impact of CPA addition to concrete.

3.6. Acid Attack Test

Exposure to acidic environments leads to degradation of concrete. To study the effects of the acid attack, CPA blended concrete specimens were given exposure to the sulphuric acid environment and the test was carried out as per American Society for Testing and Materials [21]. Sulphuric acid of 5% by weight of water was taken as the medium and the specimens were submerged in it. The concentration of the medium was maintained by replacing at day 1, day 3 and then at every 7 days. Tests for water absorption, compressive strength and loss in weight were carried out on the specimens subjected to acid attack.

3.6.1. Resistance Against Water Absorption The variation in the porosity of acid attacked specimens

were evaluated using the water absorption test. The test was conducted on acid attacked specimens immersed in dilute sulphuric acid after 28,60 and 90 days of immersion as per American Society for Testing and Materials [21].

3.6.2. Variation in weight of Acid Attacked Specimens The change in weight of the specimens immersed in

dilute sulphuric acid was noted at 28, 60 and 90 days of immersion. The specimens are then kept at room temperature for a span of 24 hours and then subjected to oven drying for 3 days at 60 oC. After that, the specimens were taken out of the oven and allowed to cool for 24 hours. After that, the weight was noted. The change in weight was expressed in terms of the initial oven-dried weight taken before immersion in acid solution.

3.6.3. Variation in Compressive strength The variation in compressive strength was checked at 28,

60 and 90 days of immersion in dilute sulphuric acid as per American Society for Testing and Materials [22]. The obtained compressive strength was compared with normal concrete specimens which are not subjected to acid attack and water cured for 28 days after casting. The reduction in compressive strength is expressed in percentage. The variation in the dimension of the specimens after acid exposure were not considered while calculating the compressive strength

3.7. Microstructural Analysis of CPA Blended Concrete by SEM

Scanning electron microscope (SEM) was used to study the microstructural properties of CPA blended cement concrete specimens. The instrument used was ZEISS EVO18 and it uses electron beams to generate the enlarged images of the internal structure of sample materials. The samples were of approximate size 5 mm X 5 mm X 5 mm and were taken from specimens subjected to compression test carried out as per IS 516: 1959 after

providing 90 days of curing. Various parameters like morphology, pore distribution and presence of hydration products were studied


4.1. Compressive Strength of CPA Blended Concrete

The compressive strength increased with curing period. Table 4 shows the compressive strength of various mixes at different curing periods. The strength of all mixes increased with increase in curing periods. CC05 mix showed better performance than CM at all curing periods. At 28 days of curing, the strength of CM and CC05 were 31.97 KN and 33.03 KN respectively. At a curing period of 90 days, the compressive strength values of CM, CC05 and CC10 were 34.66 KN, 37.98 KN and 34.70 KN respectively. Thus the strength of CC10 was observed to be slightly higher than that of CM. For CC05 and CC10 mixes, the effect of the pozzolanic reaction was well observed at 90 days of curing and it contributed to the better mechanical performance. As the percentage of CPA content increased beyond 5%, the compressive strength decreased. The decrease in strength can be attributed to a drop in cement content and a slower rate of pozzolanic reaction. The above results confirm the application and ability of the CPA to be used as a cement replacing material. However, the performance of CPA blended concrete was seemed to be lesser than that of concretes blended with other pozzolanic materials derived from agricultural by-products like sugarcane bagasse ash (SBA) and rice husk ash (RHA). From previous researches, the optimum replacement dosage of both SBA and RHA was found to be 20%. [2, 23-26]. Also, the performance of the CPA was found to be better than that of previous researches [14, 27-28].

Table 4. Compressive Strength of CPA blended concrete specimens

Mix Compressive Strength (MPa)

7th Day 28th Day 56th Day 90th Day

CM 29.11 31.97 33.62 34.66

CC05 29.43 33.03 35.81 37.98

CC10 26.85 29.44 33.21 34.70

CC15 22.45 26.71 27.07 27.96

CC20 15.73 16.98 20.06 21.13

4.2. Split Tensile Strength of CPA Blended Concrete

Similar to compressive strength, CC05 mix showed improved strength than CM at all curing periods. At 28 days of curing, the split tensile strength of CM and CC05 were 2.53 KN and 2.59 KN respectively. Increase in CPA content beyond 5% resulted in lowering of split tensile strength. Also, CC10 mix possessed higher strength than


CM at 90 days of curing. The split tensile strength of CM, CC05 and CC10 at 90 days were 2.75 KN, 3.05 KN and 2.80 KN respectively. The results of split tensile strength tests of CPA blended concrete specimens are shown in Table 5.

Table 5. Split tensile strength of CPA blended concrete specimens

MIX Split Tensile Strength (MPa)

28th Day 90th Day

CM 2.53 2.75

CC05 2.59 3.05

CC10 2.43 2.80

CC15 2.24 2.37

CC20 1.99 2.19

4.3. Flexural Strength of CPA Blended Concrete

At 28 days of curing, the best resistance against flexure was offered by CC05 mix. However, when the CPA content increased beyond 5%, the strength got reduced. The strength of CM, CC05 and CC20 at 28 days of curing were 7.61 KN, 7.81 KN and 4.93 respectively. When compared with CM, at 20% replacement, the strength reduced by 35%. The flexural strength test results are shown in Table 6

Table 6. Flexural strength of CPA blended concrete specimens

Mix Flexural Strength (MPa)

28th Day

CM 7.61

CC05 7.81

CC10 7.52

CC15 6.01

CC20 4.93

4.4. Ultra Sonic Pulse Velocity Test on CPA Blended Concrete

Table 7 shows the UPV test results and the UPV tests on specimens containing CPA showed that CM and CC05 specimens showed excellent quality at all curing periods. At 28 days, 56 days, and 90 days, the UPV of CC05 specimens were more than that of CM which shows the better quality of CC05 over CM. Increased pozzolanic reactivity of CPA due to the reduction in particle size could lead to the densification of the concrete matrix by forming more CSH gels. During the initial days, the filler effect could also increase the UPV. CC10 and CC15 specimens showed excellent quality at 28,56 and 90 days. CC20 specimens showed excellent quality on 56 and 90 days of curing.

Table 7. UPV of CPA blended concrete at various curing periods

Days of

Curing

UPV (m/s)

CM CC05 CC10 CC15 CC20

7 Days 4660 4568 4298 4051 3874 28

Days 4968 4971 4824 4618 4434

56 Days 5027 5147 5006 4872 4758

90 Days 5141 5324 5150 5012 4933

4.5. Water Absorption of CPA Blended Concrete

Water absorption of oven-dried samples were calculated after immersing the specimens in water for 48 hours. The results obtained after the test are shown in Fig. 3 and Fig. 4. At 28 days, for all the water-cement ratios, the least water absorption was shown by the specimens having 5% CPA. However, the absorption of specimens with 10% CPA was found to be less than that of the control mix. The specimens with 15% and 20% CPA showed higher absorption than the control mix. At 90 days, the specimens showed a slightly different trend. The water absorption decreased till the percentage replacement increased up to 10 %. After that, the values seemed to be increasing. When compared with the control mix, the performance of specimens with 15% CPA was better. The initial decrease in the water absorption indicates the reduction in the porosity and this can be attributed to change in microstructure due to pozzolanic action of CPA and filling of voids. However, when CPA content increased beyond a particular level, the reduced performance, especially at initial curing days could be due to slow rate of hydration of ash, the low pozzolanic activity of ash, and aggregation of particles.

Figure 3. Variation in Water Absorption (%) at 28 days


Figure 4. Variation in Water Absorption (%) at 90 days

4.6. Resistance of CPA Concrete Against Acid Environments

4.6.1. Variation in Compressive strength The compressive strength tests of specimens subjected

to acidic environments were carried out at 28, 60 and 90 days of immersion and the results obtained were compared with compressive strength of those 28 days water cured specimens which are not exposed to the acidic environment. The loss in compressive strength was expressed in percentage and are shown in Fig. 5, Fig. 6, and Fig. 7. Different water-cement ratios, 0.40, 0.45 and 0.50 were considered. In all cases, for all the mixes, the percentage reduction in strength went on increasing with the increase in exposure duration to sulphuric acid. In water-cement ratio 0.40, the maximum strength reduction was observed for CC20 mix and values at 28 days, 60 days and 90 days were 23.16%, 48.70% and 60.5%, respectively. At 60 days, and 90 days, the minimum strength reduction was seen in the case of CC05 mix. However, at 28 days, CC10 mix showed better performance than the rest of the mixes.

Figure 5. Compressive Strength loss (%) of Acid Attacked concrete specimens with w/c 0.40

At 28 days of acid exposure, for water-cement ratio 0.45, the best performance was shown by CC10 mix and the value was 20.79%. At 60 days and 90 days, CC05 mix was found to be superior to other mixes. The maximum strength reduction was shown by CC20 mix irrespective of exposure durations. The maximum values obtained for CC20 mix at 28 days, 60 days and 90 days were 23.93%, 50.68% and 59.65% respectively.


In water-cement ratio 0.50, considering the strength loss, the best and worst performances were shown by CC05 and CC20 mixes respectively, at all exposure durations. In general, considering all the water-cement ratios and exposure durations, it could be inferred that the percentage reduction in compressive strength decreased up to a certain percentage of CPA addition. Increasing CPA content beyond a particular level resulted in an increase of percentage reduction. The enhanced performance during CPA addition was due to reduction in C3A in the blended cement concrete and the pozzolanic action of CPA which depleted the Ca (OH)2 content. In addition to this, the filler effect caused by CPA addition reduced the permeability which in turn decreased the acid ingress which resulted in better strength of concrete. Higher percentages of CPA reduced the performance against acid attack due to reduction in cement content which reduced the Ca (OH)2

content in the matrix which was supposed to react with SiO2 present in CPA. Also, from previous studies, CPA showed a slower rate of pozzolanic reaction [14]. In addition to all these factors, increasing the percentage of CPA beyond a level caused its aggregation and increased the permeability of the matrix which aided the ingress of more acid to the interior sections of the specimens. Fig. 8(a), Fig. 8(b) and Fig. 8(c) show the acid attacked specimens at 28 days with 0%, 10% and 20% CPA respectively.



Figure 8 (a). The Acid Attacked Specimens at 28 days with 0% CPA

Figure 8 (b). The Acid Attacked Specimens at 28 days with 10% CPA

Figure 8(c). The Acid Attacked Specimens at 28 days with 20% CPA

4.6.2. Resistance Against Water Absorption Increase in the exposure duration resulted in the increase

in water absorption of specimens. Fig. 9, Fig. 10 and Fig. 11 shows the water absorption of acid attacked specimens with water-cement ratio 0.40, 0.45 and 0.50 respectively. Similar trends were observed in case of concrete specimens with water-cement ratio 0.45 and 0.50, at all exposure periods to sulfuric acid environments. The water absorption tend to decrease up to 5% replacement and increased beyond that percentage. The same trend was observed for the water-cement ratio of 0.40 at 28 days and 60 days of acidic exposure. However, at 90 days, the water absorption decreased beyond 5 % up to 10 % and started to increase beyond 10 %. The better performance of CC05 and CC10 mixes can be attributed to the combined effect of pozzolanic reaction and filler effect of CPA. The concrete mix will have a comparatively denser matrix which reduces the chemical ingress

Figure 9. Water absorption of specimens with w/c 0.40 exposed to Acid Attack




4.6.3. Variation in weight of Acid Attacked Specimens The variation in weight of specimens subjected to acid

attack was calculated at 28, 60 and 90 days. The variation in weight was calculated by comparing the weights of non-acid attacked specimens at 28 days of water curing with those of acid attacked specimens. The loss in weight was calculated and expressed in percentage. The variation in weight loss is shown in Fig. 12, Fig. 13 and Fig. 14.

For all water-cement ratios, at 28 days of immersion, the least weight loss was observed for CC05 mix and for all other replacement percentages, the weight loss was found to be more than that of control mix. This could be due to the pozzolanic reaction of CPA which produces additional C-S-H gel by reacting with calcium hydroxide, that improves the quality of concrete. Similarly, at 60 days of immersion, for water-cement ratio 0.40, CC05 mix showed least weight loss. But for water-cement ratios 0.45 and 0.50, the best performance was shown by CC10 mix. At 90 days, just like at 28 days, CC05 showed the best values compared to all other mixes. The reduction in performance at 90 days when compared to 60 days was due to conversion of Ca(OH)2 to gypsum which gets leached away. Since CPA

cannot react in the absence of calcium hydroxide, the pozzolanic action ceases.

Figure 12. Weight loss (%) of specimens with w/c 0.40 exposed to Acid Attack




4.7. Microstructural Analysis of CPA Blended Concrete by SEM

In the study, the various mixes taken into consideration were CM, CC05, CC10 and CC15. All samples were taken after providing 90 days of curing period. The SEM image of control mix concrete is shown in Fig. 15 and it shows the presence of dense C-S-H phase and plate-like Ca (OH)2 phase along with a considerable amount of void spaces. C-S-H phase is one of the most prominent components that influence the microstructural and mechanical characteristics of concrete.

The microstructural details of CC05 is shown in Fig. 16. Comparing the SEM images of CM and CC05 reveals that, CC05 mix possess comparatively a denser microstructure than CM. The number of pores also got reduced to a greater extend. The presence of Ca (OH)2 in CC05 was not as much as in case of CM. These details proved the pozzolanic reaction of CPA which eliminated the calcium hydroxide content in the matrix. The C-S-H phase formed from Ca (OH)2 occupied the empty void spaces and led to the formation of a denser microstructure. This in turn resulted in the superior mechanical and durability performance of CC05.

Figures 17 & 18 show the SEM images of CC10 and CC15 respectively. As far as the compactness of microstructure and voids are concerned, CC10 and CM mixes possess similar microstructural characteristics. Increase in CPA content beyond 10% led to the formation of less compacted microstructure with an increased number of pores. Even though, the amount of Ca(OH)2 is lesser due to pozzolanic reaction, the voids are more due to reduced formation of hydration products as cement content got decreased.

Figure 15. SEM image of CM at 90 days (w/c = 0.45)

Figure 16. SEM image of CC05 at 90 days (w/c = 0.45)




5. Conclusion The purpose of the research was to check the

performance of CPA as cement replacing material and to understand the mechanical and durability properties of CPA blended cement concrete. From the various tests conducted, the following conclusions were drawn. CC05 mix showed the best mechanical performance

irrespective of the curing periods. Also, at 90 days of curing, CC10 mix performed better than CM.

UPV values of all specimens were more than 3.5 km/s which showed the good quality of specimens. Similarly, at 56 and 90 days of curing, UPV of all specimens were more than 4.5 km/s which showed the excellent quality of the specimens.

The performance of CPA blended concrete against water absorption improved with the addition of CPA up to a certain percentage. The optimum percentage of CPA replacement at 90 days was found to be 15%.

The water absorption and weight loss specimens subjected to acid attack were found to decrease with the addition of CPA up to 5% replacement levels, at all curing periods, irrespective of the water-cement ratio.

For water-cement ratios 0.40 and 0.45, at 28 days of acid exposure, the percentage reduction in compressive strength was observed to decrease up to 10 % CPA replacements. In all other cases, the best performance was shown by the specimens containing 5% CPA

Also, the specimens with water-cement ratio 0.40 performed better than water-cement ratios 0.45 and 0.50.

The internal microstructural details of CPA blended specimens were studied using a scanning electron microscope. At 5% replacement level, the microstructure was found to be denser than at 0% replacement. Also, the microstructure observed at 10% replacement levels was almost similar to that at 0% replacement. The microstructure analysis supports the better the performance shown by CPA blended concrete with CPA levels up to 10%.

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Variations in Mass and Resistance Due to Accelerated Weathering Effects in Concrete Specimens Used in

Low-income Housing

Aurora Martínez-Loaiza1,*. María Teresa Sánchez-Medrano2

1Faculty of Engineering "Arturo Narro Siller", Autonomous University of Tamaulipas, University Circuit, South University Center, Tampico, Tamaulipas, Mexico

2Faculty of Architecture, Desing and Urbanism, Autonomous University of Tamaulipas. University Circuit, South University Center, Tampico, Tamaulipas, Mexico

Received August 8, 2020; Revised October 9, 2020; Accepted October 19, 2020

Cite This Paper in the following Citation Styles (a): [1] Aurora Martínez-Loaiza. María Teresa Sánchez-Medrano , "Variations in Mass and Resistance Due to Accelerated Weathering Effects in Concrete Specimens Used in Low-income Housing," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1039 - 1046, 2020. DOI: 10.13189/cea.2020.080530.

(b): Aurora Martínez-Loaiza. María Teresa Sánchez-Medrano (2020). Variations in Mass and Resistance Due to Accelerated Weathering Effects in Concrete Specimens Used in Low-income Housing. Civil Engineering and Architecture, 8(5), 1039 - 1046. DOI: 10.13189/cea.2020.080530.


Abstract The reinforced concrete used for construction represents one of the most widely used materials in urban housing. In the case of coastal areas such as Tampico, Tamaulipas, Mexico, the behavior of the concrete elements used in housing differs from less aggressive environmental areas, as evidenced by the built heritage. This work presents results in relation to causes-effects of environmental loads such as humidity, temperature, solar radiation, acid rain and carbonation on specimens of hardened concrete with f’c of 20 and 25 MPa, especially in aspects such as variations in mass and durability and even decreased early resistance. The tested specimens show a variety of relationships that illustrate the effect of the studied parameters, before and after being subjected to accelerated weathering tests; additionally, durability aspects were considered on 6 slab models designed and built to microscopically visualize fissures in the exposed faces, registering mechanical resistance through periodic monitoring that is still maintained. The study showed that concrete with fć of 20 MPa has greater mass losses and advances in the carbonation front after being exposed in an artificial accelerated aging chamber (AAA), as well as greater degradation when exposed to sulfuric acid, although with less adhesion of salts.

Keywords Acid Rain, Carbonation, Fissures,

Concrete Degradation

1. IntroductionConcrete is a material commonly used in construction,

due to its mechanical characteristics, its versatility and the geometry it can adopt, however, its durability depends on the environmental characteristics in which it is found. Products have been used to improve its resistance to compression, such as fly ash [1] as a substitute for cement, that also improves workability and CO2 reduction [2] and with a design may improve habitability [3]. To reduce degradation, tests for porosity changes and crystalline changes of the solid medium have been carried out to reduce the permeability to water [4], that may contain substances that degrade the solid. Acids are compounds that can reduce the useful life of concrete because it reacts with carbonates and in turn modifies the resistance [5], which also damage the interface of heterogeneous elements. Other components can modify the behavior of concrete mainly when it is armed with steel [6] that interacts producing corrosion which crystallizes with changes in volume and producing cracks. Studies have been carried

1040 Variations in Mass and Resistance Due to Accelerated Weathering Effects in Concrete Specimens Used in Low-income Housing

out to know the effects of carbonation on the durability of concrete and some models to produce the effects on its morphological changes [7] [8] as well as the formation of fissures through which degrading compounds can be introduced and use of some additives [9].

Chlorides are ions that can modify the properties of concrete [10] and can produce salts [11] reducing the useful life mainly with the metals that compose it [12].

Due to the above, it is important to carry out studies according to the environment where the material in question is used, in the most aggressive environments such as the marine environment, these effects are accentuated, requiring a set of additives that reduce degradation [13] that can be used in other abrasive environments, as well as taking advantage of the formation of by-products such as phosphates [14] reducing degradation.

Air components can mix with moisture droplets, which in turn travel through the solid microstructure, increasing interaction, as well as corrosion [15][7].

As an extension of the study about the effect of environmental loads on concrete slabs [16], the aim of this work is to correlate causes-effects of humidity, temperature, solar radiation and acid rain with regard to variations in mass and penetration of the carbonation front, in simple concrete specimens with f'c of 20 and 25 MPA, durability aspects are also considered on 6 slab models designed and built to microscopically visualize fissures on exposed faces, recording mechanical resistance through periodic monitoring which is still maintained.

2. Experimental Report Stage 1.- Three experimental models of roof slabs and

their corresponding series of specimens for each type of concrete were designed and built, where compliance with the properties of resistance to simple compression, flexion and capillary absorption was verified. In accordance with Mexican standards NMX-C-083-ONNCCE-2014, 150mm diameter and 300mm high compression cylinders were tested, NMX-C-191-ONNCCE-2004 600mm long beams, 150mm wide and 150 mm flexed and NMX-C-504-ONNCCE-2015 cylinders with 100 mm in diameter and 50 mm high for capillary absorption.

In the experimental models of slabs, such as those commonly used in social interest housing in the southern coastal area of Tamaulipas, the specifications of the technical standards [17] were applied. The cross section of the slab ribs is 10 cm wide with a total thickness of 15 cm, the longitudinal reinforcement in both beds with a corrugated rod with a diameter of 9.5 mm and a minimum yield stress of 42 MPa (42 degree). Under the service conditions for this type of housing, no changes are required by applying NTC-2017.

Stage 2. It consisted of obtaining information to correlate environmental loads such as changes in

temperature, humidity, the pH of precipitation and the concentration of atmospheric pollutants that can generate acid rain with respect to the injuries identified in the pathological process of slabs. For this purpose, the experimental models of slabs were monitored for a period of 18 months and two different accelerated tests were carried out on series of concrete specimens. From the three months of construction of the experimental models of slabs, the behavior of the fissures identified by direct observation was analyzed in three-month intervals.

To that end, grids were drawn on the six exposed surfaces every 20 cm, recording the location of the fissures, the width of each fissure was measured with a graduated transparent mica, a capture with a digital camera of each grid with visible fissures and a capture with a digital microscope of fissures with more than 0.5mm wide.

To simulate an accelerated process of the effects of acid rain a concentration of 1% sulfuric acid (H2SO4) was used, this concentration was selected according to the results of Yingwu Zhou et al. 2017 [18], allowing to replicate a simulation environment of concrete eroding. This was used on concrete specimens with the same characteristics as those used for capillary absorption tests, for this, the variation of the masses was determined using a balance with an accuracy of ± 0.01gr, a laboratory oven for temperatures of 50⁰C ± 2⁰C and desiccators.

Once the initial constant mass of a total of 16 specimens was determined, eight for each type of concrete, they were soaked up to a level of 10 mm in two different fluids, 6 (3 for each type of concrete) in H2O as control cylinders and 10 (5 for each type of concrete) in 1% H2SO4, remaining under these conditions for 90 hours, time in which the solution in the concrete stopped reacting as the sulfuric acid was absorbed, then the specimens were removed from the fluids and placed under drying conditions in the environment.

Subsequently, the surfaces were observed using a photographic camera and a digital microscope at 500x magnification, then proceeding to carry out the oven drying process to obtain the final dry mass. The variation of the mass was obtained by calculating the difference between the constant mass obtained after the test in accordance with the initial constant mass, for each of the specimens in both types of f'c.

The second accelerated test consisted of simulating the environmental conditions of solar radiation, elevated temperature, humidity and dew to determine possible injuries in concrete specimens through a QUV model spray accelerated artificial aging chamber.

The test procedure was carried out on concrete specimens (tablets) obtained from the cutting of 150 mm x 150 mm x 500 mm concrete beams used in bending tests. For the cutting, a Controls model 55-C0210 / BZ universal disc cutting machine was used.


The tablets obtained were measured with a 0.1 mm digital Vernier, having an average dimension of 75 mm x 150 mm x 10 mm, for conditioning the samples until obtaining a constant mass, a balance with an accuracy of ± 0.01gr, a laboratory oven for temperatures of 50⁰C ± 2⁰C and desiccators were used.

Eighteen tablets of each type of concrete were placed in the artificial accelerated aging chamber (AAA), distributed in such a way that the end panels that receive the least UV rays were free, according to the manufacturer's recommendations as indicated in the Manual [19] for accelerated weathering cameras for the ASTM G 154 cycle.

The specimens were tested for a period of 180 hours, in which a total of 15 cycles were completed, including the simulation of sunlight using ultraviolet fluorescent lamps (step 1), as well as the effects of ambient humidity, rain and dew through spray and condensation cycles in combination with elevated temperature ranges also reproducing thermal shocks and possible mechanical erosion (steps 2 and 3). The time and number of cycles were selected in accordance to the geometry of the selected probes to show a major carbonation process.

To observe possible lesions on the exposed concrete surface, microscopic photographs (500x) were taken of specimens of both types of concrete tested in an accelerated artificial aging chamber and control specimens [20]. Constant mass values were recorded in each specimen before and after the accelerated test, applying the same formula as in the sulfuric acid resistance test for variation in mass (Δm).

To determine the penetration of the carbonation front in concrete tablets previously tested in the accelerated aging chamber and in control tablets according to the protocol described by Galán [21], on a freshly cut area and after having removed the dust on the surface, it is sprayed with a 1% phenolphthalein solution in alcohol. The tested surface shows a bright pink color if the pH in the concrete maintains its original value, while there are no change in color in the carbonated areas with a pH below 8.

The carbonation depth was measured with an accuracy of 0.5 mm in each of the edges of the tested tablets, taking the average value obtained from the maximum and minimum values in each carbonate front.

From the registration carried out in each of the described tests, the results were analyzed to determine the injuries and to correlate the environmental loads studied and the injuries identified in the pathological process of the slabs.

3. Results and Discussion Figure 1 and Figure 2 show the images of the built slabs

and the tablets used for the tests.

Figure 1. Slabs built as experimental models

Figure 2. Concrete tablets

In the concrete compressive strength test, the average values obtained experimentally exceed in both cases the specified design resistance, being 19% in the specimens with fć of 20 MPa and 6% in the specimens with fć of 25 MPa. It is probable that in the case of specimens with fć of 25 MPa, the trapped air bubbles have influenced on capillary absorption values in the placement process. A greater capillary absorption is related to the interconnection between the capillary pores of the concrete or with the exterior called open porosity, when this occurs there is a decrease in resistance to the penetration of fluids or an exchange of dissolved substances between the interior of the concrete and the close environment.

From the inspection carried out on the surfaces of the concrete slabs, only contraction fissures were identified that originate from the rapid loss of water on the concrete surface before it sets, and although they are unsightly, they are not usually related to structural damage, however their presence can generate the entry of moisture and the reproduction of microorganisms such as mites over time, which could be observed through the microscope during the measurement process.

This condition can be related more to the construction process than to the design resistances, because the evaporation rates at the surface are affected by the wind speed as well as by the high environmental and concrete


temperatures; variables that were not controlled, considering that only in the first slab built with a design fć of 20 MPa the greatest number of fissures appeared and that in none of the slabs was the width greater than 0.5 mm throughout the 18-month observation period,

In each of the beams tested in flexion, the failure occurred in the central third, calculating the modulus of rupture with the corresponding equation for this case. The values of the modulus of rupture that express the tensile strength of the concrete in the flexural test represent a range between 10 and 20% of the compressive strength, a condition that was met in both types of concrete with a value of 12 % in specimens with a design fć of 20 MPa and 11% in specimens with a design fć of 25 MPa.

Table 1. Preliminary tests on concrete specimens

Design value f'c in MPa 20 25

Experimental value f'c in MPa in cylinders 23.8 26.6

Modulus of rupture in MPa in beams 2.35 2.61

Initial absorption speed in mm / s ½ 0.0242 0.0242

Initial correlation coefficients 0.9991 0.9995

Secondary absorption speed in mm / s ½ 0.0007 0.0009

Secondary correlation coefficients 0.9861 0.9888

The initial rate of absorption in specimens with f’c 20 and 25 MPa presented the same value of 0.0242 mm / s1 / 2 and the secondary rate of absorption was 1.28% higher for specimens with fć of 25 MPa compared to those of the fć of 20 MPa. The initial and secondary correlation coefficients, being greater than 98%, indicate a linear relationship that validates the results obtained. We saw that linear relationship is higher in the scale required by the Mexican Standard; the concrete absorption curve for the 20MPa samples was 8.52 ± 0.04% by weight, having a similar value for those of 25MPa.

Of the six experimental models, only the first slab built with a fć of 20 MPa, called “L-1-200”, presented a more irregular surface and contraction fissures with a maximum width of 0.5 mm. In the other slabs, the surfaces were more regular, and the width of their fissures was less than 0.5 mm.

In the observation made over time, no increase in width or new fissures were detected. Figure 3 shows images captured with the microscope at 50x magnification, visualizing the maximum width of fissures detected at three months of age.

Figure 4 shows images captured with the microscope at 50x magnification, nine months after the slabs were made, observing that the widths of the fissures remain unchanged.

Figure 5 shows microscope images captured from the last inspection performed at 18 months of age, showing that the fissure width in the L-1-200 slab remains at 0.5mm and in the L-4-250 slab the maximum width of fissures observed is less than 0.5mm.

Figure 3. Fissure width in slab “L-1-200” with 3 months of age (50x increase). (a) Ruler with an approximation of 0.5mm. (b) Mesh with an approximation of 0.1 mm

Figure 4. Fissure width in slab “L-1-200” with 9 months of age (50x increase). (a) Ruler with an approximation of 0.5 mm. (b) Mesh with an approximation of 0.1 mm

Figure 5. Maximum fissure widths at 18 months of age (50x magnification). (a) Slab "L-1-200" and (b) Slab "L-4-250"

Figures 6 show the surfaces captured under a microscope for each type of slab in 50x and 500x magnifications.

In the values obtained in the sclerometer test, the slabs designed with fć of 20 MPa present values 15% higher, registering an average resistance fć-i of 23 MPa obtained experimentally, while the slabs with design resistance fć of 25 MPa present the same experimental value fć-i of 25 MPa.

Figure 6. Slab surfaces at 15 months of age, (a) Slab “L-1-200” (50x increase) and (b) Slab “L-1-200 ”(increase 500x), (c) Slab“ L -4-250 ”(50x magnification) and (d)“ L-4-250 ”slab (500x magnification).


Regarding the constant mass values obtained before and after the sulfuric acid resistance test for each type of concrete specimens, they went from -0.59% to 0.41% for those of 20MPa, while those of 25MPa had a value between -0.48%. up to 0.61%. From the statistical analysis, it was determined that there is a direct correlation of the mass variations resulting from the sulfuric acid resistance test between the specimens of both concretes.

Regarding the weathering tests, specimens called tablets were obtained from the cutting of concrete beams with a disc cutting machine. The constant mass values obtained before and after the test in the artificial accelerated aging chamber (AAA) in the control tablets for each type of concrete (TC-200 and TC-250) with a loss of mass for 20 and 25MPa of up to 1.27% and 0.15%, respectively, due to crumbling, which corresponds to a greater interaction between the components.

Similarly, this process was applied to the tablets tested in the artificial accelerated aging chamber (AAA), they did not present significant differences for a representativeness of up to 25 years with losses of up to 0.69% and 0.13% by weight for 20 and 25MPa, respectively, and that are related to the effects of temperature, solar radiation, humidity and dew to which they are exposed (See Table 2). Considering that concrete has components linked by a set of forces that can be modified by energy waves from ultraviolet rays, responsible for the degradation of materials exposed to the elements, the exposure to solar radiation combined with high temperatures and periods of dew and condensation during the accelerated aging test, caused volumetric changes in the concrete tablets and micro-erosion of the exposed surface by crumbling of the concrete due to trapped air bubbles close to the leaking surface of mass, seven times greater in the tablets with fć of 20 MPa compared to the tablets of 25 MPa.

For the mass variations with the accelerated aging chamber, it was determined that there is a direct

correlation of the resulting mass variations between the specimens tested in EAA with fć of 20 MPa and those of fć of 25 MPa.

3.1. Carbonation Potential

The determination of the carbonation front was performed according to the established protocol applying 1% phenolphthalein solution in control tablets (CT) and tablets tested in AAA (QT) for each type of concrete, the results of the tested specimens were presented in detail in Martínez and Sánchez [16]. The advance of the carbonation front with pH values lower than 8 occurs where there is no color change, this condition was recorded in one tablet with 20 MPa fć with an average value of 2.5 mm and in two tablets with f ́ c of 25 MPa with an average value of 1 mm and 3.25 mm. The other control specimens in both types of concrete did not record carbonate areas.

The range of average CO2 penetration values measured in the tablets previously tested in the AAA chamber with fć of 20 MPa was between 3 and 5.35 mm while in the tablets with fć of 25 MPa it was 3.5 mm to 7 mm. (See Table 2). This behavior may be related to the interconnection between the pores of the concrete with fć of 25 MPa, which, even with a lower a / c ratio, presented a higher secondary absorption rate and therefore less resistance to penetration of the carbonation front, generated by subjecting specimens to changes in humidity and high temperatures. Because both types of concrete had injuries related to environmental loads that can lower their strengths, specimens with a design f’c of 20 MPa are more vulnerable. Figure 7 shows the color changes to bright pink on the sprayed surfaces where the pH retains its value, while on the surfaces where no color change was observed they indicate the advance of the carbonation front with pH values below 8, You can also observe the measurement process carried out using a graduated mica.

Figure 7. Test to determine the carbonation front with phenolphthalein (a), (b) and (c) Control 25MPa fć tablet, (d), (e) and (f) 20 MPa f'c tablet from AAA


Table 2. Injuries to tested specimens of concrete

Design value fć Mass variations by sulfuric acid in % Mass variations by AAA chamber in % Carbonation penetration in mm

20 MPa

RAS-20-1 -0.59 TQ-20-1 -0.69 TQ-20-1 3

RAS-20-2 -0.28 TQ-20-2 -0.13 TQ-20-2 4

RAS-20-3 0.16 TQ-20-3 -0.09 TQ-20-3 4.5

RAS-20-4 0.16 TQ-20-4 -0.05 TQ-20-4 5.3

RAS-20-5 0.41 TQ-20-5 -0.05 TQ-20-5 5.35

25 MPa

RAS-25-1 -0.48 TQ-25-1 -0.09 TQ-25-1 3.50

RAS-25-2 -0.37 TQ-25-2 -0.05 TQ-25-2 4.00

RAS-25-3 -0.20 TQ-25-3 0 TQ-25-3 4.00

RAS-25-4 0.37 TQ-25-4 0.09 TQ-25-4 5.25

RAS-25-5 0.61 TQ-25-5 0.13 TQ-25-5 7.00

From the statistical analysis it was determined that there is a direct correlation between the specimens tested in AAA with fć of 20 MPa and those of fć of 25 MPa with respect to the carbonation front.

Table 2 shows the lesions determined in each type of concrete specimen tested, such as mass variations by sulfuric acid, mass variations by accelerated aging chamber and carbonation penetration.

Finally, the correlation analysis was performed with Pearson's r having a value of r = 0.87 with an alpha significance level equal to 0.05, to accept that there is a correlation between the environmental loads considered in the study and the concrete injuries with resistance to specified compression, fć of 20 MPa of general use for the elaboration of concrete slabs, and concrete with fć of 25 MPa recommended under the durability criteria.

4. Conclusions From the results obtained in the preliminary tests for

both types of concrete, it is ruled out that the behavior of each tested specimens is related to poor quality once they met the design specifications. However, it could be noted that the concrete with resistance of design fć of 20 MPa, experimentally, presented higher values, having as a probable cause the dosage of the mixture, considering that only in the first slab built with a design fć of 20 MPa, the greatest number of fissures appeared, and that in none of the slabs was the width greater than 0.5 mm throughout the 18-month observation period.

Regarding the behavior of the specimens tested in sulfuric acid, the specimens with fć of 20 MPa had a 23% greater degradation and a salt adhesion 67% less with respect to the specimens with fć of 25 MPa, being 0.59 % the greatest loss of mass and 0.61% the greatest increase presented. These conditions denote the reaction processes attributed to the dosage and compounds of the cement. In both cases, the resistances can be affected by modifying the internal structure: by the empty spaces that occurred in

degradation or with the increase in mass caused by the formation of salts that occupied a greater space, with respect to the initial components of the concrete, and produce an increase in their volume.

The penetration of the carbonation front for the control tablets of each concrete was null, while there was a decrease in pH in all the tablets tested in the aging chamber, being 20% lower than those corresponding to the fć of 20 MPa.

5. Recommendations Although there are studies regarding injuries to

structures and there are organisms that have established the measurement of corrosion in reinforced concrete structures related to climatic conditions in various countries, no comparative and correlational studies have been carried out such as those presented in this document. Research work, however, it is necessary to continue making more detailed studies for each type of concrete, as well as a greater knowledge of environmental conditions, using high-tech measurement equipment such as scanning electron microscopy (SEM), infrared spectroscopy (FTIR), solid state nuclear magnetic resonance (MAS-NMR) or nuclear densitometry.

Tests in artificial aging chambers are a useful tool to analyze the behavior of structures, but further studies are required to establish equivalence parameters in camera hours in relation to the age of structures exposed to specific environmental conditions of the area. It is recommended to check the dimensions of the specimens in order to perform mechanical compression tests after exposure in the AAA chamber; case which was not achieved in this study due to equipment limitations.

Although it is true that increasing the resistance index contributes to counteracting injuries, it is not enough to avoid premature deterioration, according to the results that were obtained, it is important to continue proposing an improvement of mix designs that consider modifications


in cement consumption and possibly the inclusion of additives that improve the physical behavior of concrete structural elements; the handling of additives, the innovation in the cementing are lines that are opened at the end of this investigation, where the regulations clearly show that it cannot be applied in a generalized way, but rather than geographic, climatological and industrialization aspects must be considered in the areas where is built.

Acknowledgements Special thanks to Programa para el Desarrollo

Profesional Docente (PRODEP; Professional Teaching Development Program), for their support to the publication of this paper.

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Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for

Marine Structures

Trong-Phuoc Huynh1,*, Phuc-Huynh Bui2, Nguyen-Trong Ho3, Phuong-Trinh Bui4,5

1Department of Civil Engineering, College of Engineering Technology, Can Tho University, Campus II, 3/2 Street, Ninh Kieu District, Can Tho City 900000, Vietnam

2School of Graduate, Can Tho University, Campus II, 3/2 Street, Ninh Kieu District, Can Tho City 900000, Vietnam 3Faculty of Civil Engineering, VSB-Technical University of Ostrava, Ludvika Podesta 1875/17, 708 00 Ostrava-Poruba, Czech

Republic 4Department of Construction Materials, Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly

Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam 5Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam


Cite This Paper in the following Citation Styles (a): [1] Trong-Phuoc Huynh, Phuc-Huynh Bui, Nguyen-Trong Ho, Phuong-Trinh Bui , "Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for Marine Structures," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1047 - 1056, 2020. DOI: 10.13189/cea.2020.080531.

(b): Trong-Phuoc Huynh, Phuc-Huynh Bui, Nguyen-Trong Ho, Phuong-Trinh Bui (2020). Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for Marine Structures. Civil Engineering and Architecture, 8(5), 1047 - 1056. DOI: 10.13189/cea.2020.080531.


Abstract The purpose of this study was to evaluate the engineering properties of the high-flowing fine-grained concrete (HFFC) developed using various components such as cement, slag, fly ash (FA), natural crushed sand, crushed stone, water, and superplasticizer (SP). Six HFFC mixture proportions were prepared in the laboratory, in which three mixtures got a variety of water-to-binder (w/b) ratio in the range of 0.32–0.42 while the other three mixtures were setup from selected w/b ratio of 0.37 and the substitution of Portland cement by slag at 0 (reference), 10, 20, and 30% by mass of cement. Engineering properties of all HFFC specimens were evaluated through the tests of compressive strength, flexural strength, water absorption, porosity, drying shrinkage, and sulfate resistance. Additionally, the properties of fresh HFFC mixtures, including workability and unit weight, were measured. Test results showed that the cement replacement by slag significantly improved compressive and flexural strengths, and reduced water absorption and porosity of the HFFC samples when compared with the reference sample. Moreover, the use of slag to partially replace cement was found to enhance sulfate resistance and reduce drying

shrinkage of the HFFC samples. This study found that using slag could improve the engineering properties of HFFC for hydraulic structures.

Keywords Fine-Grained Concrete, Marine Structure, Compressive Strength, Flexural Strength, Water Absorption, Drying Shrinkage, Sulfate Resistance

1. IntroductionConcrete is one of the construction materials having a

wide range of flexible applications in the world [1], especially applying for the marine environment with a high concentration of harmfully corrosive agents such as sulfate ions. However, there are some factors influencing the life cycle and durability of these structures, such as water/cement ratio, cement content, curing condition, aggregate quality, permeability, alkali-aggregate reaction, concrete quality, sulfate attack, etc. [2]. Therefore, various technical methods are suggested to investigate

1048 Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for Marine Structures

and produce new concrete generations to extend service life and enhance the durability of the concretes for the marine structures.

Several researchers have paid attention to the application of fine-grained concrete or high-flowing fine-grained concrete (HFFC), particularly in aggressive surroundings like the marine environment. Fine-grained concrete is also called sand concrete or fine aggregate concrete, in which coarse aggregate is replaced by the finer one [3]. Nevertheless, high cement content is one of the disadvantages of fine-grained concrete or HFFC. The cement content in the fine-grained concrete is approximately 30% higher than that in the traditional concrete. A use of superplasticizer (SP) and mineral additives (e.g. fly ash (FA), slag, and so on) supports not only to decrease the cement content but also to improve engineering properties including strength, workability, water resistance, shrinkage, porosity, and so on of fine-grained concretes [4]. Moreover, the positive role of nano-sized additives in the improvement of the properties of various types of concrete including fine-grained concretes was found in some previous studies [5], [6].

On the other hand, using industrial wastes such as FA and slag as secondary raw materials plays a crucial role in sustainable development [7]. Moreover, using industrial wastes in concrete technology not only lessens greenhouse gas emissions but also creates eco-friendly concrete and brings high economic efficiency [8]. The ground blast-furnace slag is used as an additive in the Portland slag cement manufacture in some countries where a huge amount of blast-furnace slag is released from steel production [9]. In fact, blast-furnace slag was used as a partial substitution for Portland cement from 1947 to 1952. From that, the concrete containing slag as binding material has been investigated and produced [10], [11]. Topçu and Ugurlu [12] stated that the compressive and flexural strengths were significantly improved by the addition of mineral filler to the concrete, particularly fine-grained concrete or HFFC. Similarly, Malhotra proved that the slag fineness, activity index, and slag-to-cement ratio in mixtures affected the strength of concrete containing slag [13]. The water absorption and porosity decrease with the increase in the workability of concrete [14].

This study focuses on using slag as the cement replacement in HFFC to develop engineering properties of such concrete to apply in marine structures. A number of laboratory tests for compressive and flexural strengths, water absorption, porosity, drying shrinkage, and sulfate resistance were carried out for this purpose.

2. Experimental Details

2.1. Characteristics of Raw Materials

This study prepared HFFC samples using cement, slag,

FA, crushed sand, natural crushed stone, water, and SP. A blended cement-slag-FA mixture played as binder material. The physical-chemical characteristics of these binder materials are shown in Table 1. A high amount of both CaO and SiO2 could be found in cement, while major chemical compositions of slag were SiO2, Al2O3, and CaO, and the major components of FA were SiO2 and Al2O3.

Table 1. Chemical Compositions of Original Materials

Items Compositions (% by mass)

Cement Slag FA

SiO2 23.5 35.5 59.2

Al2O3 6.0 13.0 26.7

Fe2O3 3.7 0.3 6.1

CaO 59.9 38.1 1.1

MgO 2.0 8.0 0.9

Others 4.9 4.7 6.0

Density (g/cm3) 3.05 2.85 2.14 Mean Particle

Size (μm) 19.1 8.8 21.5

Specific Surface Area (m2/g) 0.78 1.68 0.66

Figure 1. XRD Patterns of Original Materials

Figure 1 shows the mineralogical compositions of the cement, slag, and FA detected via X-ray diffraction (XRD) analysis. Alite and belite were mainly found in the cement while mulite and quartz existed in the FA. In addition, the non-crystallize phase was observed in the slag. Figure 2 shows the morphology of the cement, slag, and FA via scanning electron microscopic (SEM) analysis. The cement and slag had irregular shapes while the FA had a spherical shape with various particle sizes. The physical properties of crushed sand and natural crushed stone as fine and coarse aggregates in the HFFC mixture, respectively are shown in Table 2. Tap water was used as mixing water and SP sourced from China with a density of 1.15 g/cm3 was used to obtain a high flowability of the HFFC mixtures.


(a) Cement

(b) Slag

(c) FA

Figure 2. SEM Images of Original Materials

Table 2. Physical Properties of Aggregates

Properties Density (kg/m3)

Water Absorption

(%) Remark

Crushed sand 2670 1.61 Fineness Modulus

(FM) = 3.69 Crushed

stone 2720 1.48 Maximum Diameter (Dmax) = 9.5 mm

2.2. Mixture Proportions

Based on the pre-laboratory trials, six HFFC mixtures were designed for this study. In which, three mixtures were designed with various water-to-binder (w/b) ratios of 0.32 (W32S00), 0.37 (W37S00), and 0.42 (W42S00)) and the other three mixtures were designed with the same w/b ratio of 0.37 along with various slag contents as cement replacements. A constant aggregate-to-binder ratio (by weight) of 2.73 was applied for all of the HFFC mixtures. In this study, the controlled HFFC mixture denoted as W37S00 was designed using the densified mixture design algorithm (DMDA) with the procedures as described by Hwang and Hung [15]. The replacement ratios of cement by slag were 10, 20, and 30% for the W37S10, W37S20, and W37S30 mixtures, respectively, while the amounts of FA and aggregates were kept constant for these mixtures. The dosage of SP was adjusted in order to control the designed slump values for all of the HFFC mixtures in a range of 25 ~ 30 cm. The mixture proportions for all of the HFFC samples are given in Table 3.

Table 3. Mixture Proportions for the Preparation of HFFC Samples

Mixtures Materials (unit: gram)

Cement Slag FA Sand Stone Water SP

W32S00 3213 0 644 7027 3495 1234 26

W37S00 3213 0 644 7027 3495 1427 22

W42S00 3213 0 644 7027 3495 1620 18

W37S10 2892 321 644 7027 3495 1427 22

W37S20 2570 643 644 7027 3495 1427 21

W37S30 2249 964 644 7027 3495 1427 20

2.3. Sample Preparation and Test Methods

A procedure of sample preparation was carried out as follows: (1) binder materials including cement, slag, and FA were dry-mixed in a laboratory mixer for one min; (2) two-thirds of mixing water was gradually added to the mixer followed by a part of SP; (3) all components were continuously mixed for two min to obtain a viscous paste; (4) aggregates were added to the paste followed by the rest part of water and SP; and (5) mixing was allowed to continue for two min in order to obtain a homogenous mixture. After mixing, the fresh properties of HFFC mixtures were immediately tested. Then, the HFFC samples were cast in various sizes for different test purposes as per the relevant standards. It is noted that all of the HFFC samples were de-molded one day after casting and then cured in lime-saturated water until the testing ages.

The fresh properties of the HFFC mixtures including slump, slump flow, and flow time were measured in accordance with TCVN 12209:2018 [16] while the fresh unit weight was measured in accordance with TCVN 3108:1993 [17]. The compressive strength test was


performed at 1, 3, 7, 14, and 28 days according to TCVN 3118:1993 [18] using the cubic samples with dimensions of 10×10×10 cm. Meanwhile, the flexural strength test was performed at 7 and 28 days according to TCVN 3119:1993 [19] using the prism concrete with dimensions of 15×15×55 cm. The tests of water absorption and porosity of the HFFC samples were conducted at 28 days as per TCVN 3113:1993 [20] using the cubic samples with dimensions of 10×10×10 cm. The tests of drying shrinkage and sulfate resistance of the HFFC samples were evaluated through the change in length of the prism concretes with dimensions of 7.5 × 7.5 × 28.5 cm that cured at room conditions and immersed in a 5% Na2SO4 solution, respectively. The length change of the samples was monitored at 1, 3, 7, 14, and 28 days following the ASTM C157 [21]. The average value of repeated three measurements was reported for each test at each age.

3. Test Results and Discussion

3.1. Fresh Properties

Table 4 represents the fresh properties of all HFFC mixtures, including slump, slump flow, and flow time. For the W32S00, W37S00, and W42S00 mixtures, the mixture with a lower w/b ratio had a higher flow time than the others. Meanwhile, the mixture with a w/b ratio of 0.37 had a slump of 26 cm, a slump flow of 62 cm, and a flow time of 4 sec. Therefore, based on the experiment results, a w/b ratio of 0.37 was chosen as an optimum w/b for the reference mixture.

It is clearly observed that the SP dosage in the mixtures containing slag (W37S20 and W37S30) slightly decreased when compared with the reference mixture containing no slag (W37S00). Additionally, the mixture with the replacing 10% cement by slag (W37S10) consumed the same SP amount as the reference mix (see Table 3). The SP dosage was found to be decreased as further increasing the slag replacement in the HFFC mixtures. The reduced SP dosage is due to the reduction in water demand of slag particles, which is attributable to the lower rate of slag hydration as compared to cement [22]. Moreover, the replacement of cement by slag also reduces the ettringite formation during the early stages of hydration, resulting in the improvement of the workability of the concrete mixture [23]. Thus, it can be concluded that slag required a low SP dosage to reach the designed slump flow with a constant mixing water amount.

The variation of unit weight in a fresh state of mixtures with the cement substitution by slag is also shown in Table 4. It is expected that the unit weight in the fresh state of HFFC with high slag replacement decreases with the increase in the slag replacement because the unit weight of slag is usually lower than that of cement [24]. In this study, the unit weight of HFFC mixtures with 10, 20, and 30%

slag replacements was lower by 0.4, 0.6, and 1.2% than that of the reference sample with 0% slag replacement (W37S00).

Table 4. Properties of Fresh Concrete Mixtures

Mixtures Slump (cm)

Slump flow (cm)

Flow time (sec.)

Unit weight (kg/m3)

W32S00 25 59 10 2324

W37S00 26 62 4 2309

W42S00 28 58 3 2269

W37S10 25 59 5 2300

W37S20 26 63 6 2295

W37S30 26 61 5 2282

3.2. Compressive Strength

The compressive strength of HFFC samples with various w/b ratios at the ages of 1, 3, 7, 14, and 28 days is illustrated in Figure 3. At 28-day age, the compressive strengths of samples with w/b ratios of 0.32, 0.37, and 0.42 were 45.6, 38.2, and 35.3 MPa, respectively. It can be seen that an increase in w/b ratio decreased the compressive strengths of HFFC samples by approximately 3–7% at all ages. The reduction of the w/b ratio led to a decrease in microcracks between aggregate particles and cement paste, and porosity in the hardened concrete [25], [26]. Consequently, the compressive strength can be improved as the w/b ratio decreases. This trend is in line with the previous study [27]. During the experimental work, it is found that the HFFC samples with a w/b ratio of 0.37 exhibited good performance in both fresh and hardened stages so this ratio was selected to evaluate the effect of various slag replacements on the properties of HFFC samples.

Figure 3. Compressive Strength of the HFFC Samples with Various w/b Ratios

On the other hand, the effect of slag replacements on the compressive strength of HFFC samples at the ages of


1, 3, 7, 14, and 28 days is illustrated in Figure 4. Generally, the compressive strength of concrete, particularly HFFC specimens increases with normal curing time due to the cement hydration and the pozzolanic reaction of binder materials [28]. This tendency was also observed in this study. At 28-day age, the compressive strengths of HFFC samples with 0, 10, 20, and 30% slag replacements corresponded to 38.2, 38.6, 40.2, and 43.6 MPa. Figure 4 also reveals that the compressive strength of samples with 10, 20, and 30% slag replacements increased by approximately 1, 5, and 15%, respectively when compared with the reference sample with 0% slag replacement at the same age. Furthermore, it can be seen that the higher the slag replacement, the higher the compressive strength of HFFC specimens at 7-, 14-, and 28-day ages, but not at early ages (i.e., at 1- and 3-day ages). This is due to the cement replacement by slag which resulted in a decrease in the early-age strength but an increase in the later-age strength.

Figure 4. Compressive Strength of the HFFC Samples with and without Slag Replacements

3.3. Flexural Strength

The flexural strength is a vital engineering property of HFFC because it reflects the tension and deformation resistance of concrete. Marine structures often bear high water pressure and high deflection in a harsh seawater environment [29]. Thus, the higher the flexural strength value, the better the quality of concrete and versa vice. The flexural strength of three HFFC mixtures corresponding to various w/b ratios at 7- and 28-day ages is presented in Figure 5. At 28-day age, the flexural strengths of HFFC samples with w/b ratios of 0.32, 0.37, and 0.42 were 10.9, 9.5, and 8.2 MPa, respectively while these values at 07-day age were 10.0, 8.2, and 7.6 MPa. Similar to the compressive strength test, a reduction of the w/b ratio generally increases the flexural strength of the concretes.

Figure 5. Flexural Strength of the HFFC Samples with Various w/b Ratios

The flexural strength of HFFC samples with and without slag replacements at 7- and 28-day ages is shown in Figure 6. Similar to the compressive strength, the flexural strength of HFFC increased with curing time and also increased with an increase in slag replacement. At 28-day age, the flexural strengths of HFFC samples with 0, 10, 20, and 30% cement replacements by slag were 9.5, 9.7, 9.9, and 10.6 MPa, respectively. It can be seen that the flexural strength of the HFFC samples with 10, 20, and 30% cement replacements by slag improved by 2, 4, and 12%, respectively when compared with the reference concrete without slag. It is revealed that although slag is known as a pozzolanic material and plays a crucial role in the strength development, a low slag replacement (i.e., 10 or 20% replacement) did not help significantly enhance the flexural strength of the HFFC.

Figure 6. Flexural Strength of the HFFC Samples with and without Slag Replacements


3.4. Water Absorption and Porosity

All marine structures always work in a seawater environment with many corrosive agents like sulfate ions and chloride salts or acids. In this condition, the resistance to chemical attack of hydraulic concrete is really important. Water absorption and porosity values at 28-day age reasonably reflecting the corrosion resistance of HFFC with various w/b ratios are shown in Figure 7. The water absorption values increased from 8.3, 8.9, and 10.6% corresponding to the HFFC mixtures of W32S00, W37S00, and W42S00, respectively. This is because the water absorption of concrete was greatly affected by the w/b ratio. In general, the higher the w/b ratio, the higher the pores generated from the free water evaporation in concrete [26]. In fact, the porosity of the HFFC increased as an increasing w/b ratio and achieved 3.6, 3.9, and 4.8% corresponding to the HFFC mixtures of W32S00, W37S00, and W42S00, respectively.

Figure 7. Water Absorption and Porosity of the HFFC Samples with Various w/b Ratios

The water absorption and porosity of the HFFC samples with and without slag replacements at 28-day age are shown in Figure 8. According to Figures 7 and 8, the water absorption value of the reference mixture (W37S00) was 8.9%. When the cement replacement by slag at levels of 10, 20, and 30%, the water absorption values of the HFFC samples were 8.6, 7.7, and 6.3%, respectively. It is clear that the water absorption of mixtures tended to decrease when the replacement ratio of ordinary Portland cement by slag increased. This result is appropriate with a previous study of Topçu and Ünverdi [30]. The main reason for the decrease in water absorption is due to the less porous structure of concrete, which is partially filled by slag. The fine particles of slag could block some continuous pore network in the matrix, leading to the reduction in water absorption of concrete [22]. In addition, the pozzolanic reaction of slag generated secondary calcium-silicate-hydrate (C-S-H) gel, which is attributable to the reduction in capillary and gel porosity and consequently reducing water absorption rate of the

concrete [31].

Figure 8. Water Absorption and Porosity of the HFFC Samples with and without Slag Replacements

Similar to the water absorption, the porosity of the HFFC specimens decreased as the slag replacement increased (see Figure 8). The porosity values were 3.9, 3.7, 3.0, and 2.8% corresponding to the HFFC samples with 0, 10, 20, and 30% slag, respectively. The water absorption was increased proportionally with the porosity (Figure 9). This correlation is presented by the linear equation of y = 1.895x + 1.488 (R2 = 0.93). In which, x and y represent for porosity and water absorption rate, respectively. It is apparent that the porosity had a direct influence on the strength of concrete [27] as a reduction of the concrete strength is caused by higher porosity as mentioned.

Figure 9. The Relationship between Water Absorption and Porosity of the HFFC Samples

3.5. Drying Shrinkage

Drying shrinkage of HFFC samples with various w/b ratios is given in Figure 10. The test was evaluated through the length change of the HFFC mixtures with various w/b ratio cured at room conditions from the age of 1 to 28 days. It can be seen that drying shrinkage decreased by approximately 15% with the reduction of w/b and drying


shrinkage increased by about 20% during the curing time. During the drying process, water loss in the samples caused drying shrinkage, and the increase in the w/b ratio can increase the volume of capillary pore and decreased the water loss barrier [26]. As a result, the increase in w/b and curing time can lead to an increase in the drying shrinkage.

Figure 10. Change in Length of the HFFC Samples with Various w/b Ratios

Figure 11 shows the length change of the HFFC mixtures with various slag replacements cured in lime-saturated water until 28-day age. At 28-day age, the drying shrinkage values achieved 0.032, 0.030, 0.025, and 0.020% corresponding to the HFFC specimens with 0, 10, 20, and 30% slag, respectively. From these experimental results, the drying shrinkage of samples reduced with increasing slag replacement. At an early age (i.e., at 1 day), the length change suddenly tended to increase when increasing the slag replacement and this tendency was contrary to the HFFC mixtures at later ages. Additionally, the results of this study also indicated that a partial replacement of Portland cement by slag reduced drying shrinkage when compared with the reference mixture containing no slag and it is appropriate with results reported in previous research [32].

Figure 11. Change in Length of the HFFC Samples with and without Slag Replacements

3.6. Sulfate Resistance

Sulfate attack is one of the most important problems concerning the durability of hydraulic concrete structures, especially in the sulfate environment like seawater. The influence of the w/b ratio on the sulfate attack resistance of test samples was therefore analyzed and is shown in Figure 12. In this study, the length change of mixtures immersed under 5% Na2SO4 solution was used to evaluate the resistant ability to sulfate attack. The change of length was at 0.019, 0.023, and 0.027% corresponding to the HFFC mixtures with the w/b ratios of 0.32, 0.37, and 0.42, respectively. It is apparent that increasing the w/b ratio of HFFC specimens increased their length change, which is primarily due to the increment of porosity and shrinkage of the concrete [25], [26].

Figure 12. Change in Length of the 5% Na2SO4-Immersed HFFC Samples with Various w/b Ratios

The influence of slag replacement on the sulfate attack resistance of test samples was also analyzed and is shown in Figure 13. At 28-day age, the length change values reached 0.023, 0.021, 0.019, and 0.016% corresponding to the HFFC with 0, 10, 20, and 30% slag replacements. According to this research, it is concluded that the length change of HFFC samples reduced when increasing the replacement ratio of Portland cement by slag. This finding is also in line with the results from previous studies [33], [34]. Moreover, due to its high fineness, slag is a common material that is widely used to substitute for ordinary Portland cement to improve the engineering properties of concrete structures in the marine environment. With very high fineness, the addition of slag into concrete can effectively fill the pores of the concrete to reduce the permeability of concrete [30] and make concrete more impermeable. Additionally, Islam et al. [34] stated that slag would react with the cement hydration products to form secondary C-S-H gel. This also takes account of making impermeable concrete to restrict the penetration of sulfate ions from seawater inside the HFFC, consequently reducing the risk of sulfate-induced deterioration.


Figure 13. Change in Length of the 5% Na2SO4-Immersed HFFC Samples with and without Slag Replacements

4. Conclusions The effect of a partial replacement of Portland cement by

slag on the engineering properties of high-flowing fine-grained concrete (HFFC) applying in the marine environment was investigated in this study. Three water-to-binder ratios used were 0.32, 0.37, and 0.42. Three replacement ratios of Portland cement by slag were 10, 20, and 30% by mass was prepared for the HFFC with a selected w/b ratio of 0.37. Based on the experimental results, the following conclusions can be drawn:

First, as increasing the substitution of cement by slag, the unit weight of fresh HFFC mixtures was reduced because the unit weight of slag was lower than that of cement.

Second, when increasing the w/b ratio, the compressive strength of the HFFC specimens intended to reduce by 3–7% at all ages of the concretes. Meanwhile, the compressive strength improved by 1, 5, and 15% corresponding to the 28-day-old HFFC specimens with 10, 20, and 30% slag replacements.

Third, a reduction of the w/b ratio generally increased the flexural strength of the HFFC. When the substitution of cement by slag at 10, 20, and 30% by mass, the flexural strength of the HFFC improved by 2, 4, and 12%, respectively.

Fourth, the water absorption of the HFFC specimens was significantly influenced by the w/b ratio. The water absorption had a positive relationship with the porosity of the HFFC. Moreover, slag plays a crucial role in decreasing water absorption and porosity of HFFC samples, resulting in improving the strength and durability of such concrete applying for marine structures.

Fifth, in the w/b ratio range of 0.32–0.42, the increase in w/b ratio increased the drying shrinkage of the HFFC by approximately 15% whereas curing time led to increase drying shrinkage about 20%. However, at a given w/b ratio of 0.37, drying shrinkage tended to reduce corresponding

to the increase in cement replacement by slag. Sixth, for the resistant ability to sulfate attack, increasing

the w/b ratio intended to increase the length change of the HFFC specimens while the slag replacement reduced the length change of the HFFC specimens containing slag.

Seventh, the HFFC developed in this study can be widely applied in the real construction industry not only for marine structures but also for other construction activities with considering the requirements for each specific application.

Acknowledgments The authors would like to express the special thanks to

Mr. Van-Hien Pham, Mr. Trong-Binh Pham, and Mr. Tri-Khang Lam at Can Tho University, Vietnam for valuable assistance during the experimental works.

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Effect of Metakaolin and Condensed Silica Fume on the Rheological and Structural Properties of

Self-compacting Concrete

S. Vijaya Kumar1,*, B. Dean Kumar*, B L P Swami3

1Department of Civil Engineering, Vasavi College of Engineering, Hyderabad, India 2Department of Civil Engineering, Jawaharlal Nehru Technological University, Hyderabad, India

3Department of Civil Engineering, Methodist College of Engineering and Technology, Hyderabad, India


Cite This Paper in the following Citation Styles (a): [1] S.Vijaya Kumar, B.Dean Kumar, B L P Swami , "Effect of Metakaolin and Condensed Silica Fume on the Rheological and Structural Properties of Self-compacting Concrete," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1057 - 1062, 2020. DOI: 10.13189/cea.2020.080532.

(b): S.Vijaya Kumar, B.Dean Kumar, B L P Swami (2020). Effect of Metakaolin and Condensed Silica Fume on the Rheological and Structural Properties of Self-compacting Concrete. Civil Engineering and Architecture, 8(5), 1057 - 1062. DOI: 10.13189/cea.2020.080532.


Abstract This article deals with the comparison between the metakaolin and condensed silica fume contributions in the flyash based self-compacting concrete (SCC). Self-compacting concrete with mineral admixtures like flyash and condensed silica fume is prepared by cement replacing partially at 20 and 10 percentages respectively. M40 grade of the concrete was designed by adjusting the ratio of the fine aggregate to the total aggregate volume to fulfill the requirements of the SCC. Another M40 grade of SCC is designed with the flyash and metakaolin as the mineral admixtures with the same percentage of replacement for cement by mass. Rheological properties are examined as per EFNARC specifications for flowability; passing ability and segregation resistance for both the triple blended self-compacting concretes (TBSCC). For getting the required flowability of concrete and for modifying the viscous nature of the concrete, superplasticizer and viscosity modifying agents are additionally added to the concrete. The structural properties like compression and split tensile strengths of the specimens are recorded by conducting the standard tests. By comparing the strength results, it is concluded that metakaolin and silica fume have only marginal changes between them in the rheological as well as the mechanical properties of the triple blended self-compacting concrete.

Keywords Self-compacting Concrete, Triple Blended, Metakaolin, Condensed Silica Fume, Flyash, Rheology of the Concrete, Structural Properties, Superplasticizer, Viscosity Modifying Agent (VMA)

1. IntroductionCompaction of the concrete has a very significant role in

obtaining the required strength of the concrete. But in the fabrication of thin concrete structural elements, the compaction is too difficult, and also for placing the fresh concrete in the dense reinforcement zones. To overcome these difficulties, in the late 90’s Okamura, Ochi and Ozawa have introduced the self-compacting concrete technique. With this, the concrete fills all the places of the formwork by its weight and there is no need for the compaction for becoming dense. The self-compacting concrete can be placed either by pouring or pumping, depending upon the structural elements like slab, beam, and column. Due to the addition or replacement of mineral admixtures such as flyash, condensed silica fume, and metakaolin the workability property of the concrete is influenced and also enhances the structural properties like compression, tensile and flexural strengths. The chemical

1058 Effect of Metakaolin and Condensed Silica Fume on the Rheological and Structural Properties of Self-compacting Concrete

admixture like superplasticizer (SP) improves the flowability of the concrete. The viscosity of the fresh concrete is modified by incorporating the viscosity modifying agent (VMA) along with SP.

Masahiro Ouchi [1] studied the influence of the superplasticizer on the properties of the self-compacting concrete. In this article, the authors concluded that the dosage of the superplasticizer on the volume of the concrete will affect the rheological properties, and an optimum dosage is evolved. Cyr. M, Mouret [2] did the experimental investigation on the rheological characterization of super plasticized cement pastes containing mineral admixtures, and the consequences on self-compacting concrete. There was improvement reported in the flowability of concrete. Brouwers, H, Radix, H [3] studied the experimental way of obtaining self-compacting concrete and a theoretical approach was also given by the authors. P. Dinakar and S. N. Manu [4] gave the mix design for high strength self-compacting concrete using metakaolin as one of the mineral admixtures. Siddique, R [5] investigated the contribution of class F flyash on the properties of the self-compacting concrete. Corinaldesi, V, Moriconi, G [6] investigated the characterization of self-compacting concrete prepared with different fibers and mineral admixtures. Siddique, R [7] examined the coal flyash and the bottom ash contributions on the strength properties of self-compacting concrete, and the authors also studied the water to cement ratio’s effect on the fresh and hardened properties of SCC. Assem Hassan and Mohammed lakherim [8] studied the effect of metakaolin and silica fume on the rheology of the self-compacting concrete. Vikassrivastava, Rakesh Khanna [9] examined the effect of silica fume and metakaolin on the structural properties of the concrete. Ramanathan, P [10] conducted the tests on the performance of self-compacting concrete containing different mineral admixtures, and conclusions are drawn from the experimentation giving that mineral admixtures play a major role on the strength of the SCC. Ioannis P. Sfikas [11] did the experimental investigation on the rheology and mechanical properties of the self-compacting concrete containing metakaolin and presented improved results. Hafez E. Elyamany [12] studied the effect of the filler type of material on the physical, mechanical, and microstructural properties of the self-compacting concrete. Akinpelu, MA [13] did the experimental work for the evaluation of the relation between splitting tensile strength and the compressive strength of self-compacting concrete. EFNARC-2005(The European Federation of National Associations Representing for Concrete-Specifications for the self-compacting concrete) [14] gave the detailed specifications for SCC. The details of various tests to be conducted for the flowability of SCC were also given. ACI (American Concrete Institute)237R-07-2007[15] gave the various recommendations on the preparation, flowability, and tests for SCC. The objective of this research article is comparison between the admixtures which will contributed

rheological and structural properties of the SCC.

2. Material and Mix Design

2.1. Material Used

2.1.1. Cement

53 grade of Ordinary Portland Cement (OPC) confirming to IS:10269-2015 [16] is used as binding material. The specific surface area of this cement is around 2800cm2/gram, specific gravity is 3.15, and the consistency of the cement is 32%. All these physical properties of the OPC are satisfied by the sample.

2.1.2. Fine Aggregate

River sand is used as a fine aggregate in this experimentation. The fineness modulus of this sand is determined and recorded as 2.82. Depending upon the percentage of passing in the various sizes of the sieves, it is confirmed that this fine aggregate is confirming to Zone –II. The specific gravity of this material is 2.64. These are fulfilling the provisions of IS:383-2016 [17].

2.1.3. Coarse Aggregate

As per specification of the code of practice for the coarse aggregate IS:383-2016[17], the physical properties of these materials such as specific gravity, bulk density, and fineness modulus are recorded as 2.64,1610 kg/m3, and 6.78 respectively.

2.2. Mineral Admixtures

2.2.1. Flyash (FA)

In this experimentation, the F type flyash was used as the main supplementary cementitious material (SCM). It is obtained from the Ramagundam thermal power plant in Andhra Pradesh, India. The specific surface area of the flyash is recorded as 4750 cm2/gm by conducting Blaine’s permeability test. The cement can be replaced by this type of flyash ranging from 15% to 25% by mass of the cement. The optimum percentage may vary depending upon the application. In this work, 20 % of this mineral admixture is used as SCM.

2.2.2. Condensed silica fume (SF)

Condensed silica fume consists mainly of silica in non-crystalline form and contains a large percentage of active silicon dioxide (SiO2). This admixture is used to replace OPC by 9-15%. In this work, 10 % of CSF is used as a replacement of cement because of its high specific surface area which is around 15000 cm2/ gram.

2.2.3. Metakaolin (MK)


Metakaolin is the most effective pozzolanic material for use as partial replacement to OPC because it has more compatible properties with the cement. It is a by-product and is formed by calcination of clay. It may be used to replace cement at ranges of 5-10% by weight of the cement. In this experimentation, 10 % of Metakaoline is used for the replacement of cement.

The physical and chemical properties of all these mineral admixtures are shown in tables 1 and 2. The mineral admixtures were used at optimum percentages as a replacement to OPC. In this experimentation, mineral admixtures are added in one set of concrete as 10% CSF, and 20% FA, and in another set of concrete as 10% MK, and 20% FA.

2.3. Chemical Admixtures

A high-performance superplasticizer based on polycarboxylic ether (PCE) is used in this experimentation as a superplasticizer(SP). It is commercially available as Glenium B233. In addition to this, VMA (Viscosity Modifying Agent) is also used to minimize the tendency of the highly fluid mix to segregate. Commercially it is available as Glenium-2. These chemicals are supplied by M/s BASF INDIA LTD.

2.4. Mix Design

Based on physical properties like specific gravity, fineness modulus, and other values, the M40 grade of normal concrete(NC) is designed as per IS 10262-2009[19] specification. The proportion of the materials shown in table 3. The mix design for SCC can be obtained by rearranging the fine aggregate to the total aggregate volume ratio between 0.54 to 0.68. After so many trials, the following mix for SCC is adopted which is fulfilling the primary requirements like flowability, passing ability, and segregation resistance as per EFNARC [14]. Final proportions of the materials are given in table 4.

Table 1. Physical properties of admixtures

S no Properties Flyash Condensed silica fume

Meta- kaolin

1 Specific Gravity 2.30 2.20 2.50

2 Specific

Surface Area (cm2/gram)

3500 - 3800

150000 200000 7000 - 9000

3 Colour Grey Dark grey white

4 Structure Mostly globular

Non- crystalline

Non- crystalline

Table 2. Chemical composition of various mineral admixtures (percentages) **

S no Oxides Flyash Condensed

silica fume Metakaolin

1 Silicon di oxide SiO2

55 90 52

2 Aluminum oxide Al2O3

20-70 1 40

3 Ferric Oxide Fe2O3 10-15 0.03 1.20

4 Calcium Oxide Cao 1.63 0.10 2.0

5 Magnesium oxides 3.96 0.20 0.65

6 Sulfur trioxide SO3 0.65 23 0.00

**The above data is collected from ACI international seminar on High volume Flyash and Blended concrete – 2001[18].

Table 3. M40 grade mix as per IS 10262-2009[19] for NCC (Normal Cement Concrete)

Cement Fine Aggregate Coarse Aggregate W/ C

1 1.38 2.4 0.45

Table 4. M40 grade mix as per EFNARC[14] for SCC (Self-Compacting concrete)

cement Fine Aggregate Coarse Aggregate W/ C

1 2.33 1.37 0.45

Table 5. Mix Identification

Mix for M40 grade of SCC Abbreviation

M1-SF0MK0FA0 Mix1 with 0% of condensed silica fume,0% of metakaolin,0%flyash

M2-SF0MK0FA30 Mix2 with 0% of condensed silica fume,0% of metakaolin,30% flyash

M3-SF0MK10FA20 Mix3 with 0% of condensed silica

fume,10% of metakaolin,20% flyash

M4-SF10MK0FA20 Mix4 with 10% of condensed silica fume,0% of metakaolin,20% flyash

Here cement is blended with mineral admixtures like flyash, condensed silica fume, and metakaolin for a total of 30% replacement to cement. For one set of concrete, it is 30 % replacement of flyash alone, for remaining two sets of the concrete flyash is blended with condensed silica fume and metakaolin.

2.5. Properties of the Fresh Self-compacting Concrete (Rheological properties)

The rheological properties of the fresh concrete are flowability, passing ability, and segregation resistance which are determined by slump cone test, V-funnel test, and L-box test respectively. The mixed abbreviations, the quantities of materials, and rheological test results are shown in tables 5, 6, and 7.


Table 6. Quantity of Materials per M3of Concrete (M40), with Admixtures

Mix Cement (Kg)

Fine aggregate

(Kg)

Coarse aggregate

(Kg)

Condensed silica fume

(Kg)

Metakaolin (Kg)

Flyash (Kg)

Superplasticizer (SP)

Percentage of concrete

Viscosity modifying

agent (VMA) Percentage of

concrete

Water (liter)

M1 455 1065 625 0 0 0 1 0.1 205

M2 318 1065 625 0 0 136 1 0.1 205

M3 318 1065 625 0 46 91 1 0.1 205

M4 318 1065 625 46 0 91 1 0.1 205

Table 7. Rheological properties of the Tri-blended Self Compacting Concrete. (TBSCC)

Mix Slump flow in mm V funnel in seconds L- box in the ratio H2/H1* Remarks

M1-SF00MK00FA00 610 9 0.88 *H2-height of concrete in vertical

limb,H1-height of concrete in horizontal

limb

M2-SF00MK00FA30 630 7 0.90

M3-SF0MK10FA20 650 6.5 0.91

M4-SF10MK0FA20 680 5 0.92


It is observed that the rheological properties of these triple blended self-compacting concrete (Table 7) are found to be as per the norms of the EFNARC (14) specifications. In the SCC mix mentioned in table 4, it is observed that the mineral admixtures have influenced the primary properties of the SCC like passing, free-flowing, and no segregation. For all the mixes mentioned in table 5, along with the mineral admixtures, superplasticizer and viscosity modifying agents were added up to 1.0 and 0.1 percentages by weight of the cement respectively. It is indicated (table) that SCC with flyash and condensed silica fume as mineral admixtures which replaced cement at 20,10 percentages respectively by mass (M4) have better rheological properties, compared to the other combination of the admixtures at the same percentages. Because the C-S-H gel bond is more in this combination of the mix.

3.1. Mechanical Properties of the Mixes

For determination of the structural properties of these triple blended self-compacting concrete, standard cubes, and cylinders were cast as per the specifications of the Indian standard code. The curing period for these samples

is 28 days. The basic strengths are evaluated by conducting the compressive, and the split tensile tests as per IS-516[20].

3.2. The Compressive Strength

For obtaining the getting the compressive strength results, a total of 36 standard cubes of size 150 mm x 150mm x 150 mm were cast for four combinations of the mixes (Table 7). These samples were tested at 3 days, 14 days, and 28 days. The variation of these strengths is plotted in fig 1. The best mix for getting more compressive strength of SCC is 10 % condensed silica fume with a 20 % flyash (M4-SF10MK0FA20). From these results, it can be seen that Mix-M4 (20 % flyash and 10% condensed silica fume) has 28 days strength which is marginally more compared to the same grade of Mix with 20% flyash and 10% metakaolin. (M3-SF0MK10FA20)

The best-fit log curve for this compressive strength is arrived as,

fcc= 29.415ln (t) + 16.049, Where, fcc compressive strength in MPa(N/mm2), for M4

mix and, t is the age of the concrete sample in days.


Figure 1. Variation of the compressive strength of SCC with different percentages of the admixtures

Figure 2. Variation of the Split tensile strength of SCC with different percentages of the admixtures

3.3. The Split Tensile Strength

For the above 4 combinations of the concrete mixes, a total of 36 number of standard cylinders of size 150mm diameter and 300mm height were cast. These samples were cured for 3days, 14 days, and 28 days in potable water. The final test results are plotted in fig 2. The better mix (M4) with 10% condensed silica fume and 20 % flyash has shown the highest split tensile strength. Mix-M4 which has 20% flyash and 10% condensed silica fume has 28 days split tensile strength more than the same grade of Mix-M3, with a 20% flyash and 10% metakaolin. The best fit linear curve for this strength is given by Fct = 0.44 t+ 3.2933, where

Fct - The split tensile strength in MPa (N/mm2) for M4, t is the age of the concrete sample in days.

4. Conclusions The concluding remarks on the present experimental

investigations are given as follows.

1) Mineral Admixtures like flyash, silica fume, metakaolin etc contribute towards better flowability of the concrete. The condensed silica fume because of its high specific surface area(fineness) has given better flowability compared to metakaolin. Hence, the combinations of flyash with silica fume has given better flowability compared to the combination of flyash with metakaolin.

2) Chemical admixtures like super plasticizer and viscosity modifying agents are necessary to maintain the rheological properties of SCC. They influence the strength and durability properties to certain extent.

3) Due to the combination of flyash and metakaolin there is some increase in the strength properties of SCC. The strength increase due to the combination of flyash and silica fume is more than the former because of higher fineness of silica fume.

4) The silicate content in the condensed silica fume is much more than the other admixtures and this causes more C-S-H gel formation and it results in more flowability without segregation.


5) The flow of the SCC which has condensed silica fume as one of the admixtures is 12 percent more compared to the basic SCC without mineral admixture. The flow of the SCC with metakaolin is only 6% higher compared to the basic. This has been established as a result of workability test conducted on SCC.

6) The structural properties of the tri-blended SCC have shown that 10% CSF and 20% flyash combination has given optimum values of compressive strength, and the split tensile strength. These values are around 10% and 8% more in comparison with basic SCC.

Acknowledgments The authors are very thankful to the Vasavi College of

Engineering, for permitting to utilize the resources in the concrete laboratory, also special thanks to UGC for sanction of the fund for this project.

REFERENCES [1] Masahiro Ouchi, Makoto Hibino, Hajime Okamura, “Effect

of superplasticizer on self-compatibility of fresh concrete,” Transportation research record journal of the transportation research boards1574: page no:37-40,1997.

[2] CYR.M, Mouret,"Rheological characterization of superplasticizer cement paste containing mineral admixtures”, Consequences on Self-Compacting Concrete Design Special Publications page no:241-256. (2003)

[3] Brouwers, H, Radix, H, "Self-compacting concrete, the theoretical and experimental study”, cement and concrete research, Elsevier publications, Issue 35 Page no:2116-2136. (2005).

[4] P. Dinakar and S N Manu, "Concrete mix design for high strength self-compacting concrete using metakaolin”, Journal of construction and building materials, Elsevier publications, Volume -60, Issue 3 Page no:661-668., (2010).

[5] Siddique R, "The properties of the self-compacting concrete containing the class F flyash”, Material and design journal, Elsevier publications, Volume -32, Page no:1501-1507, (2011).

[6] Corinaldesi V, Moriconi, G,, “Characterization of self-compacting concrete prepared with different fibers and mineral admixtures”, Cement and Concrete Composites, Elsevier publications, Volume -33, Page no:585-601,(2011)

[7] Siddique R, Aggarwal P and Aggarwal Y (“Influence of water/powder ratio on strength properties of self-compacting

concrete containing coal flyash and bottom ash”, Journal of construction and building materials, Elsevier publications, Volume -29, Page no:73-81. 2012)

[8] Assem Hassan and Mohammed lakherim, “Effect of condensed silica fume and metakaolin on the rheology of the self-compacting concrete”. IOSR Journal of structural and civil engineering, Volume-5, Issue 8, page no:318-325, (2012)

[9] Vikas Srivastava, Rakesh Khanna and Mehta P K, “Effect of condensed silica fume and metakaolin combination on the concrete”, International journal of civil and structural engineering, Volume 2, issue 3, page no:895-900. (2013)

[10] Ramanathan P, Baskar I, Muthupriya. P and Venkatasubramani R, “The performance of self-compacting concrete containing different mineral admixtures”, KSCE journal of civil engineering, Volume 17, Pageno:465-472, (2013).

[11] Ionnais P sfikas, Efstratios G Badiog Ionnis and Konstantin G.T, “Rheology and structural properties of the self-compacting concrete mixes containing metakaolin”, Journal of Materials and construction, Elsevier publications, Volume -32, Page no:121-127. (2014)

[12] Hafez E elyamany, and. Elymoaty and Basma Mohamed, “Effect of filler type of material on physical, structural and microstructure properties of the self-compacting concrete”, Journal of cement and composites, Elsevier publications, Volume -53, Page no:295-307. (2014),

[13] Akinpelu M A, Odeyemi S O, Olafusi and Muhammed FZ, “Evaluation of the splitting tensile strength and compressive strength relationship of self-compacting concrete”, Journal of King Saud University-Engineering Sciences. (2017)

[14] EFNARC-2005- “European Federation of National Associations Representing for Concrete-specifications for the self-compacting concrete”

[15] ACI 237R-07-2007, “Emerging technology series on self-consolidating concrete –reported by American concrete institute revised ACI manual of concrete practice (MCP)

[16] IS:10269-2015-Bureau of Indian standards-Ordinary Portland cement-specifications-sixth edition, New Delhi, INDIA.

[17] IS:383-2016- Bureau of Indian standards-Coarse and fine aggregate for concrete-specifications- New Delhi, INDIA.

[18] ACI international seminar on High volume Flyash and Blended concrete – 2001.

[19] IS:10262-2009- Bureau of Indian standards-Guidelines for concrete mix design proportioning- New Delhi, INDIA.

[20] IS:516-reaffirmed 2004- Bureau of Indian standards-Methods of Tests for Strength of the concrete- eighteenth reprint-2006-New Delhi, INDIA


DOI: 10.13189/cea.2020.080533

Determination of Black Site Area Based on Equivalent

Accident Number Analysis: Case Study National

Roads in Ambon City

Lenora Leuhery, Hamkah*

Department of Civil Engineering, Politeknik Negeri Ambon, Indonesia



(a): [1] Lenora Leuhery, Hamkah , "Determination of Black Site Area Based on Equivalent Accident Number Analysis:

Case Study National Roads in Ambon City," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1063 - 1073, 2020.

DOI: 10.13189/cea.2020.080533.

(b): Lenora Leuhery, Hamkah (2020). Determination of Black Site Area Based on Equivalent Accident Number Analysis:

Case Study National Roads in Ambon City. Civil Engineering and Architecture, 8(5), 1063 - 1073. DOI:

10.13189/cea.2020.080533.


Abstract This study was conducted to determine

accident-prone areas (black sites) on national roads in

Ambon City using the Equivalent Accident Number (EAN)

and Upper Control Limit (UCL) criteria. Primary data was

obtained by direct survey. Meanwhile, secondary data was

obtained from various sources related to the number of

traffic accidents in Ambon City. The data were analyzed

using simple statistical methods and tabulated based on the

number of accidents in 2019. The analysis results showed

that the high severity of traffic accidents in Ambon City

was 91.95% caused by driver behavior factors. Three other

factors that cause traffic accidents include drunkenness,

carelessness, and drowsiness. The study results showed

five black site areas on national roads in Ambon City based

on EAN value higher than the UCL value. These locations

include roads: Jenderal Sudirman, Pierre Tendean, Wolter

Monginsidi, Laksdya Leo Wattimena, and Putuhena.

Meanwhile, the Sisingamangaraja road segment has a

higher EAN value than the UCL value but not the national

road segment (province road segment). Based on these

results, several things need to be done to overcome the

accident rate. Therefore, national road management

agencies and stakeholders, especially those related to the

black site area, are advised to: build road medians, add

zebra cross-shaped crossing facilities and be equipped with

shelters in the road median, complete traffic signs installed

with signs that read accident-prone area, build pedestrian

protective fences, and traffic management engineering.

Keywords Black Site, EAN, UCL, Traffic Accidents

Prone, National Road Segment, Ambon City

1. Introduction

Traffic accidents are a severe problem for many

developing countries in the world. Under vehicle growth

not followed by a good road infrastructure improvement [1]

will affect the accident rate significantly. In Indonesia, high

accident rates occur in big cities [2], [3], and Ambon City is

no exception. To reduce the accidents number and victim

fatalities, WHO (2006) established the Global Road Safety

Partnership (GRSP) [4]. United Nations member states

asked to formulate short-term and long-term strategic

policies in minimizing the number and consequences of

road accidents. According to the Ministry of

Transportation (2010), 90% of accident cases occur in

developing countries like Indonesia [4].

Meanwhile, in 2019 the Indonesian National Police

recorded 107,500 traffic accidents, increasing 3% from

2018, as many as 103,672 accidents [5]. Indonesia's

commitment to the United Nations Decade of Road Safety

Action is required by establishing a National General Plan

for Traffic and Land Transportation Safety, aiming to

reduce the fatalities rate due to traffic accidents by 50% in

1064 Determination of Black Site Area Based on Equivalent Accident

Number Analysis: Case Study National Roads in Ambon City

2020 [4]. Various efforts were made to improve the traffic

system by involving related parties, reduce traffic accident

victims' numbers and continuously create safe traffic.

One effort to reduce the accident rate is the road safety

campaign [6]. Accidents prone areas based on road type in

Surabaya City are roads with type 4/2UD [6]. Therefore,

for Ambon City with 35 segments, there are only 5 points

with a very worrying median [4]. The lack of knowledge

and information of the community regarding road signs and

markings increases accident risk.

An appropriate analysis or study is needed to determine

accident-prone areas' locations and characteristics in

Ambon City. Three components were interrelated with

traffic operations in improving traffic safety on the road:

drivers, vehicles, and roads. Vehicles have a profound

effect on accident causes. However, elements of road

geometry such as section length, number of lanes, and

horizontal curves significantly impact the incidence of

accidents. Most of the accident victims found in a very

productive age group. The age of group people ranges of 15

to 49 years old.

Identifying, analyzing, and improving accident-prone

areas were the most critical accident prevention [7]. The

studies related to accident-prone areas were carried out in

two districts in Hanoi-Vietnam, concluding that the

accident data were summarized and illustrated in the

Vietnam police ledger. It is causing difficulties to evaluate

accidents. Another study conducted in the Republic of

Srpska on traffic safety between 2012 and 2017 concluded

that in addition to the accident level, regulatory issues,

accident costs, and performance audits should also be

considered [8]. Pedestrian safety is also important to note.

Installing speed tables on roads can reduce the pedestrian

accidents rate to zero [9]. Traffic safety is also affected by

the minimum road distance. A study on determining the

minimum length of entry and exit of an incline a toll road in

Indonesia shows that the resulting minimum road distance

for the 4-lane case of fatal accident model is 6 km; for

injuries accidents is 5 km, and the total accident is 4 km

[10]. However, an accident schema symbol system and

cause accident analysis seem more accessible and more

effective [11]. The random accident location analysis

ranking based on the Weighted Accident Number (WAN)

value was studied and concluded that the National Road in

Lampung Province indicated five accident-prone areas [12].

The study of black spot analysis using the EAN and UCL

methods in Kupang City revealed two locations identified

as accident-prone areas. [13].

Besides, the study evaluated of responsible riding

program on reducing the motorcycle accident rate. The

traffic safety campaign program for road users in Surabaya

City was carried out by the Surabaya Police, Surabaya

Police Satlantas Unit, and Jawa Pos on several major road

users in Surabaya. The campaign focuses on road safety

standards such as: using an Indonesian standard helmet

(SNI), not driving beyond the 40km/hour speed limit, not

making zigzag paths and prioritizing vehicles already on

their track, not using cellphones when driving, not

violating traffic lights, and crossing on zebra crossing has

shown a significant result in reducing the rate of

motorcycle accidents [14].

Various results of this study can be used as a reference in

reducing motorized accident risk, given the lack of

information and knowledge of the Ambon City community

about safety riding, reading traffic signs, and road

markings [4]. This study is expected to contribute valuable

information as a public warning to be more careful when

driving and for related agencies to plan better and more

precise handling efforts reducing traffic accidents risk in

Ambon City. Therefore, this study aims to examine traffic

accidents causes in Ambon City and calculate their severity.

It intended to update data on accident-prone areas based on

several previous studies as traffic accident data on the

prone area are located and solution recommendations,

particularly in Ambon City national roads.


2.1. Definition of a Traffic Accident

Traffic accidents are part work of accidents. According

to Indonesia government regulations No. 34 (1993): a road

accident involving a vehicle with or without other road

users, resulting in human casualties or property loss.

Meanwhile, according to Indonesian Law No. 3 (1995):

traffic accidents are the final events of unintentional events

series in death, serious/minor injuries, disabilities, and

material loss, or object damage occur on public roads.

According to WHO, a traffic accident occurs when a

motorized vehicle collides with another object and causes

damage. The incident resulted in death or injury to humans

and animals.

Based on these three definitions, the traffic accident is an

unexpected, unplanned, and sudden accident occurring on

the highway due to the road's human activity error.

Accidents cause injury, illness, and loss, both to humans,

property, and the environment. Traffic accident victims are

humans due to traffic accidents. The severity of accident

victims (casualty) is divided into fatality killed, serious

injuries, and minor injuries.

2.2. Factors Causing Accidents

A traffic accident is caused by many factors, basically

due to the ineffective combination of four main factors:

Human, Environment, Road, and Vehicle [15]. To regulate

these four main elements, laws, regulations, and standards

governing traffic safety requirements are required.

According to article 1, Indonesian government

regulations No. 44 (1993) regarding vehicles and drivers,

such as road traffic and transportation law regulation. A


driver is a person who drives a motorized vehicle or a

person who directly supervises a prospective driver who is

learning to drive a motorized vehicle. Vehicle drivers, both

motorized and non-motorized vehicles, are the leading

causes of accidents, so they need attention.

Vehicles are devices that can move on the road,

consisting of motorized and non-motorized vehicles. A

motorized vehicle is a vehicle that is driven by technical

equipment located in that vehicle. Motorized vehicles can

group into motorbikes, passenger cars, buses, goods cars,

and special vehicles. Every motorized vehicle must equip

with braking equipment, which includes the primary and

parking brake and has a wheel system that consists of the

wheels and axles. Besides the wheel system, a motorized

vehicle also has a suspension in support that can withstand

loads, vibrations, and shocks to ensure safety and

protection for its users. Additional lights on motorized cars

can reduce the risk of accidents.

The road properties and condition are very influential as

a traffic accidents cause. Improvement of road conditions

affects accident properties. Roads are designed and

maintained for safety and based on analysis results of road

function, traffic volume, composition, design speed,

topography, human factors, vehicle weight and size, social

environment, and funds [16]. If the implementation is

forced to deviate from the standard provisions, information

on accident-prone areas must post immediately before a

road is open to the public. Also, in prone locations, an

explicit notification must be given about the road condition

so that drivers know the surrounding circumstances and

more careful.

The geometric road planning must account for the traffic

that will pass on the road, the road slope, the horizontal

alignment, the intersections, and the cross-section

components. The information can be road dividing line

form specially used at night, equipped with reflective paint,

roadside posts, cat's eyes, and markers with reflective

paint.

2.3. Traffic Accident Severity

A traffic accident victim is a person who is a victim of a

traffic accident. In general, the severity caused by traffic

accidents is divided into three types: 1) death (fatal), 2)

serious injury, and 3) minor injury. An accident that does

not involve other road users is called a single accident.

Besides, there are still traffic accidents without casualties,

namely accidents with only property loss (only property

damage = PDO accidents). The impact of traffic accidents

based on an injury can be classified into four levels. A fatal

accident is an accident victim confirmed due to a traffic

accident within 30 days after the accident. Serious

Accidents are victims of accidents due to injuries sustained

by permanent disabilities or must hospitalize within 30

days from the accident. An event is a lifelong disability if a

limb is lost or cannot be used and cannot recover forever.

Minor Accidents are accidents that do not require

hospitalization for 30 days, only causing material loss.

2.4. Equivalent Accident Number (EAN)

The equivalent accident number use for weighting

accident class based on accident value with material

damage or loss. The EAN is an economy scale weighing

accident rates. It is calculated by comparing estimated

economic losses caused by different accident levels, i.e.,

death (M), serious injury (B), minor injury (R), or only

property damaged (K). The technique of identifying

accident ratings carried out by determining accident weight.

There are several types of accidents based on victim

severity. So that way, the accident number is synchronized

to become an accident weight. The weight value depends

on the method used. In Indonesia, some analysis techniques

used are as follows. First, the collision equivalent number

with a weighting system refers to accident cost

(Engineering Committee for Standardization of

Transportation Infrastructure, 2004): M: B: R: K = 12: 3: 3:

1; 2). Secondly, Accident Point Weightage (APW) method.

The method divides severity level into four main categories,

one of them having the following weights [17]: M: B: R: K

= 6: 3: 0.8: 0.2. Third, the equivalent accident number is

calculated by adding up accidents for each kilometer of

road length and then multiplying the weight value

according to the severity. Standard weights used are [18]:

M: B: R: K = 12: 6: 3: 1; 4). Fourth, the Indonesian Police's

collision equivalent number: M: B: R: K = 10: 5: 1: 1.

Therefore, there are several recommended EAN values for

determining accident-prone areas. The EAN value uses a

rationalized average cost, as shown in Table 1.

Table 1. Equivalent Accident Number (EAN)

The Severity

Methods The Average of

Rationalization Research and

Development Center APW Indonesian Police

Land

Transportation

Death (M) 12 6 10 12 10

Major (B) 3 3 5 6 4.25

Minor (R) 3 0.8 1 3 1.95

Material Loss (K) 1 0.2 1 1 0.8



In Indonesia, several recent studies related to the

determination of accident-prone areas for several large

cities using the EAN criteria have been carried out. Arung

and Widyastuti (2020) surveyed the accident-prone area in

the City of Surabaya and produced three roads as black site

areas: Ahmad Yani, Mastrip, and Ir. Soekarno [19].

Pradana et al. (2019) has reported an analysis of traffic

accidents and their causes on the Cilegon highway. The

study results show that three roads have an EAN value

greater than UCL [20]. Also, Widiyanti (2016) has reported

the results of a study on accident-prone areas using EAN

and UCL in the Banyuasin Regency. The survey results

using the EAN method show the black site on the

Palembang-Jambi road section [21].

2.5. Upper Limit Control (UCL)

Determination of the accident-prone area using statistics

with the Upper Control Limit (UCL) method as shown in

Equation 1.

(1)

Where:

= Average accident rate per exposure

Probability Factor = 2,576

m = Exposure Units, in kilometers

Road segments with an accident value (EAN) above

UCL are defined as accident-prone areas. The probability

factor (y) value is determined as a large accident rate that

cannot be considered a random event. The probability

factor (y) is shown in Table 2. The most commonly used

values are 2,576 with a probability of 0.005 (or 99.5%

significance) and 1.645 with a possibility of 0.05 (or 95%

significance). The UCL criteria are one of the methods

used to determine accident-prone areas. The other

techniques are accident frequency, accident rate,

equivalent accident number, Z-score, and cumulative

summary.

The UCL method is commonly used in Indonesia; it is

shown by several previous studies that have used this

method [19-21]. The results obtained using several

analytical methods offer the same black site area, but the

calculated value of each is different depending on the

criteria used.

2.6. Accident-Prone Area

Accident-prone areas have the highest accident rate, the

highest accident risk, and the road's highest accident

potential. Accident-prone areas identified on certain roads

are known as black sites. The general criteria that can use

to define a black spot are; a) has a high accident rate; b) the

accident location is relatively accumulated; c) accidents

occurred in somewhat the same space and period; d) have a

specific cause of the accident.

3. Methodology of Study

3.1. Location of Study

The study location on traffic accident severity and

accident-prone areas (black sites and black spots) is the

national road connecting Yos Sudarso Port and Pattimura

Airport in Ambon City. Also, Pattimura Airport and

Hunimua Ferry Pier in Central Maluku Regency [22] are

shown in Figure 1.

3.2. The Steps of Study

This activity is carried out in a structured and systematic

manner with stages according to scientific studies.

Generally, it includes 1) Determine goals and objectives to

be achieved solutions accident-prone areas on national

roads in Ambon City. 2) A literature study is a stage of

tracing suitable theoretical sources and becomes a

reference in conducting various analyzes. 3) The study

method is the stage of implementing the study according to

the sequence of activities. 4) Accident-prone areas study

discusses black site areas in the national road

accident-prone areas in Ambon City, and 5) Conclusions

and recommendations are conclusions that present a

summary of the study results and the solutions to the

findings in the form of advice.


Remark: National roads in Ambon City Figure 1. Road network map in Ambon City

4. Result and Discussion

4.1. Traffic Accident of Ambon City Based on 2019

Data

Based on several references and data sources, accident

data on national roads in Ambon City during 2019 is

tabulated according to the road segment names and the

accident's month. Table 2 presents traffic accidents number

according to the month of occurrence for 35 roads,

including national highways status in Ambon City. Four

hundred sixty-eight incidents represent accident numbers

from January to December of 35 roads segment in Ambon

City.

Based on the accident number, the black site area is

classified as a five national road segment, each have a

description of the highest total events as follows: Jenderal

Sudirman (34 incidents), Pierre Tendean (28 incidents),

Laksdya Leo Wattimena (28 incidents), Ir. M. Putuhena

(27 incidents), and Wolter Monginsidi (23 incidents).

Sisingamangaraja road, although the total number of 22

incidents is relatively high, is not yet classified as a black

site area. It still depends on the EAN calculation and not

national road status.

The human casualty severity data, a breakdown

according to minor injuries, serious injuries, and deaths are

presented in Table 3. The death fatality, which is the worst

result of a traffic accident described based on the national

road segment and accident rate each month, as follows:

Jenderal Soedirman six months (February, March, July,

August, September, and October), Pierre Tendean four

months (April, June, July, August), Wolter Monginsidi six

months (January, April, May, October, November,

December), Laksdya Leo Wattimena six months (April,

July, September, October, November), Ir. M. Putuhena,

eight months (January, February, March, April, May,

September, November, December). The severity of

Sisingamangaraja road is high for five months, but it is not

classified as a black site (not national road status).

Therefore, the five black site areas above ranked as the

highest accident number, and roads cause the highest

severity (death).



Table 2. The traffic accidents number in 2019 of Ambon City

Road Segment

Segment

Length

(km)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Amahusu 11.58 2 1 2 2 2 3 1 2 1 1 17

Dr. Malaiholo 1.62 4 2 3 2 2 2 1 3 19

Dr. Kayadoe 1.49 3 1 2 2 1 1 10

Dr. Tamaela 0.35 3 1 2 1 1 1 1 1 11

Diponegoro 0.62 1 4 2 1 1 2 11

Ahmad Yani 0.54 2 3 1 6

Rijaly 0.64 1 1 2 2 2 1 9

Jenderal

Soedirman 2.90 4 3 5 3 1 4 2 3 2 1 6 34

Pierre Tendean 3.30 2 3 1 1 2 3 2 1 1 5 2 5 28

Wolter

Monginsidi 4.24 1 2 1 2 4 3 3 2 3 2 23

Laksdya Leo

Wattimena 5.61 1 1 3 4 2 1 3 5 3 5 28

Ir. M. Putuhena 9.23 1 2 2 1 2 3 2 1 2 3 3 5 27

Syaranamual 3.42 2 1 1 2 3 6 15

Sisingamangaraja 3.25 6 1 1 3 1 2 4 2 2 22

Dr. Leimena 3.05 1 1 2 3 3 2 3 3 18

Dr. Siwabessy 0.96 1 3 2 3 1 1 3 2 1 17

Philip

Latumahina 0.41 2 1 1 1 1 1 7

Dr. Sitanala 0.35 1 1 3 1 1 1 8

Sultan Baabulah 0.63 1 2 1 1 1 2 2 1 11

A.Y. Patty 0.46 1 2 2 1 1 2 2 1 1 1 2 1 17

Said Perintah 0.39 1 1 1 1 1 1 6

Pattimura 0.55 1 3 1 2 1 1 2 2 3 3 19

Wem Reawaru 0.18 3 1 1 3 1 1 1 1 12

Sultan Khairun 0.47 1 2 2 1 2 8

Kakialy 0.29 1 1 1 2 1 1 1 8

Tulukabessy 0.39 2 2 1 2 7

Sultan

Hasanuddin 2.46 2 1 2 5

Setia Budi 0.53 1 1 1 1 2 6

W.R.Suprtaman 0.25 1 1 1 3

Kapitan Ulupaha 0.17 1 1 2 1 1 2 1 9

Jan Paays 0.31 1 1 2 1 1 1 7

A.M. Sangadji 0.26 2 3 2 1 2 3 2 15

Anthony Reebok 0.33 1 2 2 1 1 1 1 3 12

Yos Sudarso 0.48 1 1 1 1 4

Imam Bonjol 0.39 1 1 1 1 1 1 2 1 9

Total 30 421 28 40 33 38 35 28 31 60 39 65 468

Source: Data on accident rate in 2019 [4]


Table 3. Severity of human victims in 2019

Road Segment

Segment

Length

(km)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Amahusu 11.58 2 1 2 2 2 3 1 2 1 1 17

Dr. Malaiholo 1.62 4 2 3 2 2 2 1 3 19

Dr. Kayadoe 1.49 3 1 2 2 1 1 10

Dr. Tamaela 0.35 3 1 2 1 1 1 1 1 11

Diponegoro 0.62 1 4 2 1 1 2 11

Ahmad Yani 0.54 2 3 1 6

Rijaly 0.64 1 1 2 2 2 1 9

Jenderal

Soedirman 2.90 4 3 5 3 1 4 2 3 2 1 6 34

Pierre Tendean 3.30 2 3 1 1 2 3 2 1 1 5 2 5 28

Wolter Monginsidi 4.24 1 2 1 2 4 3 3 2 3 2 23

Laksdya

Wattimena 5.61 1 1 3 4 2 1 3 5 3 5 28

Ir. M. Putuhena 9.23 1 2 2 1 2 3 2 1 2 3 3 5 27

Syaranamual 3.42 2 1 1 2 3 6 15

Sisingamangaraja 3.25 6 1 1 3 1 2 4 2 2 22

Dr. Leimena 3.05 1 1 2 3 3 2 3 3 18

Dr. Siwabessy 0.96 1 3 2 3 1 1 3 2 1 17

Philip Latumahina 0.41 2 1 1 1 1 1 7

Dr. Sitanala 0.35 1 1 3 1 1 1 8

Sultan Baabula 0.63 1 2 1 1 1 2 2 1 11

A.Y. Patty 0.46 1 2 2 1 1 2 2 1 1 1 2 1 17

Said Perintah 0.39 1 1 1 1 1 1 6

Pattimura 0.55 1 3 1 2 1 1 2 2 3 3 19

Wem Reawaru 0.18 3 1 1 3 1 1 1 1 12

Sultan Hairun 0.47 1 2 2 1 2 8

Kakialy 0.29 1 1 1 2 1 1 1 8

Tulukabessy 0.39 2 2 1 2 7

Sultan

Hasanuddin 2.46 2 1 2 5

Setia Budi 0.53 1 1 1 1 2 6

W.R.Suprtaman 0.25 1 1 1 3

Kapitan Ulupaha 0.17 1 1 2 1 1 2 1 9

Jan Paays 0.31 1 1 2 1 1 1 7

A.M. Sangadji 0.26 2 3 2 1 2 3 2 15

Anthony Reebok 0.33 1 2 2 1 1 1 1 3 12

Yos Sudarso 0.48 1 1 1 1 4

Imam Bonjol 0.39 1 1 1 1 1 1 2 1 9

Total 30 421 28 40 33 38 35 28 31 60 39 65 468

Remark:

Fatality death

Serious injuries

Minor injuries



Table 4. Causes of Accidents of Ambon City in the 2019 period

Causes of

Accident

2019 Period

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Drunkenness 27 17 26 19 27 16 15 21 24 29 20 10

Drowsiness 7 2 4 5 2 1 3 3 4 2 1 2

Recklessness 23 12 16 14 18 7 11 13 12 19 12 5

Vehicles 3 2 1 2 0 1 0 2 0 1 1 0

Road 1 0 2 1 0 1 1 1 0 0 1 0

4.2. Causes of Accident Data

The traffic accident data are classified according to the

black site (road segment) in the 2019 period. Several

factors cause accidents: drunkenness, drowsiness,

recklessness, vehicles, and roads. The data used for traffic

accident characteristics analysis in Ambon City. The

results of compiling data based on various sources were

shown in Table 4.

Based on Table 4, the cause of Ambon City accidents is

dominated by motorist behavior that does not comply with

the highway's driving rules [23]. Drunk driving was the

leading cause of the accident rate at 53.40%, followed by

reckless driving at 34.47%. The study results are the

following studies conducted in Makassar City and several

other Indonesia [2], [3]. Other contributing factors, such as

drowsiness while driving, vehicle factors, and road

conditions [24], are insignificant because each value is less

than 10% [4].

4.3. Weight Analysis of Traffic Accident Based on EAN

and UCL Criteria

An equivalent accident number (EAN) is one of the

calculation methods to determine accident-prone areas.

After knowing each parameter's value, the next step is to

identify a section, including the locations prone to traffic

accidents. By using control limits (UCL), it was expected

that the results of the EAN value analysis can exceed the

UCL standards.

The EAN value analysis results for all road conditions in

Ambon City in 2019 are presented in Table 5. This

weighting uses the standards of the Indonesian National

Police. Table 5 found five roads have the highest EAN

value more than UCL value for 2019. The road segments

are Jenderal Sudirman, Pier Tendean, Wolter Monginsidi,

Laksdya Wattimena, and Ir. M. Putuhena. The five roads

with the highest EAN scores than the UCL value were

black site locations. These roads' physical characteristics

generally have upward vertical alignment with sharp bends,

and without medians or warning signs and lighting. When

driving, users only rely on their vehicle sign lights. It is

dangerous for motorists if crossing the road carelessly,

even less if it is related to who often do not heed existing

traffic signs or rules.

When road conditions are out of control, improvement

needs proper knowledge and understanding—an education

in the area around the black spot to protect themselves

better. Public awareness is high to care for vehicles early

that there is a desire to defend themselves. Educational

efforts through outreach will further increase public

awareness.

Black spot location is a specific location point in a black

site area on roads in Ambon City. Locating stationing in an

area (road segment) black site determines the black spot

detail point. The accident number on the black site within a

specified period, and road length divided by stationing

length and the time interval studied. The following is a

location analysis of the black site area and road length data

in 2019, shown in Table 6.


Table 5. Analysis of the 2019 EAN Value

Road

Segment

No.

Road Segment Total

Death

Total

Major

Injuries

Total

Minor

Injuries

Total

Victims Death

Major

Injuries

Minor

Injuries

EAN

Value

UCL

Value

1 Amahusu 0 12 5 17 0 60 5 65 81

2 Dr. Malaiholo 0 13 6 19 0 65 6 71 82

3 Dr. Kayadoe 0 5 5 10 0 25 10 35 78

4 Dr. Tamaela 0 8 3 11 0 40 3 43 79

5 Diponegoro 0 7 4 11 0 35 4 39 78

6 Ahmad Yani 0 5 1 6 0 25 1 26 76

7 Rijaly 0 4 5 9 0 20 5 25 76

8 Jenderal Soedirman 18 16 0 34 180 60 0 240 94

9 Pierre Tendean 7 20 1 28 70 100 1 171 90

10 Wolter Monginsidi 14 9 0 23 140 45 0 185 91

11 Laksdya Leo

Wattimena 15 13 0 28 150 65 28 243 95

12 Ir. M. Putuhena 18 9 0 27 180 45 27 252 95

13 Sisingamangaraja 8 12 2 22 80 60 2 142 88

14 Syaranamual 0 10 5 15 0 50 5 55 80

15 Dr. Leimena 2 14 2 18 20 70 2 92 84

16 Dr. Siwabessy 4 11 2 17 40 55 2 97 84

17 Philip Latumahina 0 3 4 7 0 15 4 19 75

18 Dr. Sitanala 1 7 0 8 10 35 0 45 79

19 Sultan Baabula 0 2 9 11 0 10 9 19 75

20 A.Y. Patty 2 9 6 17 0 45 6 51 80

21 Said Perintah 0 4 2 6 0 20 2 22 76

22 Pattimura 2 9 8 19 20 45 8 73 82

23 Wem Reawaru 0 5 7 12 0 25 7 33 77

24 Sultan Hairun 0 4 4 8 0 20 4 24 76

25 Kakialy 0 4 4 8 0 20 4 24 76

26 Tulukabessy 0 4 3 7 0 20 3 23 76

27 Sultan Hasanuddin 0 0 5 5 0 0 5 5 76

28 Setia Budi 0 2 4 6 0 10 4 14 75

29 W.R.Suprtaman 0 2 1 3 0 10 1 11 75

30 Kapitan Ulupaha 2 5 2 9 20 25 9 54 80

31 Jan Paays 0 5 2 7 0 25 2 27 76

32 A.M. Sangadji 0 6 9 15 0 30 9 39 78

33 Anthony Reebok 0 1 11 12 0 10 11 21 76

34 Yos Sudarso 0 0 4 4 0 0 4 4 77

35 Imam Bonjol 0 2 7 9 0 20 7 27 76

Table 6. The black site road segment length data of Ambon City in 2019

Black Site Area Road Segment Road Length (km)

1 Jenderal Soedirman 2,9

2 Pierre Tendean 3,3

3 Wolter Monginsidi 4,24

4 Laksdya Leo Wattimena 5,61

5 Ir. M. Putuhena 9,23

Source: P2JN [25]



The EAN analysis results in Table 5 shows that six roads

are categorized as black site areas. The length of each road

segment, as shown in Table 6, is used to determine

accident-prone black spots with these results. The findings

obtained from the black site area direct survey are essential

to analyze all accident-prone areas in Ambon City. Road

geometric of Jenderal Soedirman (black site 1) is a

downhill or incline road. The road condition does not have

a median or barrier between the two traffic lanes. It is one

reason drivers are often negligent not paying attention to

the lane dividing line and taking the driver's path from the

opposite direction. Another cause of a black spot on

Jenderal Sudirman road is that vehicles from both different

directions rarely use low speeds when passing through this

area. Traffic conditions where cars are prohibited from

cutting off the flow, but people disobedience attitude,

behaves to cut the flow without thinking other drivers,

triggering an increase in accidents. There should be no

movement of motorized vehicles on this route that reduces

the two-way lane because it is hazardous for drivers against

the current and those in the actual path.

The next black site location is the Pierre Tendean road

segment. The road section area without side obstacles, and

just relatively quiet, makes drivers drive their vehicles at

high speeds. The minimum lighting also frequent factor

accidents occur. Also, there are roads with steep curves and

turns. Drivers who drive vehicles at high speed cannot

control their cars, especially if they are drunk or sleepy.

Motorists of productive age only carry out the behavior

because they drain the springs from that location right at

the pipe. A lot of wastewater on the roadside spreads to the

asphalt surface so that the asphalt road is often potholes

and bumpy. If you are in a downhill position and the

vehicle is at high speed, it will be very prone to accidents.

Wolter Monginsidi road segment generally has flat road

contours and a slightly uphill road contour. The people at

this location are only on the east side because the west side

is a beach with mangroves. The severe contours and

slightly winding roads, coupled with lack of traffic signs,

and awareness of both two-wheeled and four-wheeled

riders, are feared to increase accidents.

At the black site, the Lakdsya Leo Wattimena road

segment has land-use conditions, which are attractions for

economic movements. The road with a three-way

intersection is the cause of frequent accidents at this

location. The road contours are straight, but the habit of

stopping vehicles carelessly, and lack signs and control in

the area, has made the people around the location unaware

of traffic safety. The road is single access to the two

crossing ports and many beach recreation areas in Central

Maluku Regency.

While on Ir. M. Putuhena road segment has a new road

section. The road section is connected to the Merah Putih

Bridge, which connects the waters inside Ambon Bay. At

night the street lights are still lacking at some point, so that

the area very dark. It is dangerous if pedestrians want to

cross because of lack of lighting (street lights) at night and

the zebra crossing that is no longer visible on the road.

Several bends, unmarked intersections, and people who do

not obey the signs or are not careful when driving, also

contribute to frequent accidents. The high mobility in this

area is also triggered by land use around the road. The

campus and residential areas on this road location will

trigger the high accident victims at a productive age.

5. Conclusions and Recommendations

The high level of traffic accident severity in Ambon City

(91.95%) was caused by the driver's behavior factor. Three

other factors that cause traffic accidents include

drunkenness, recklessness, and drowsiness. Five black site

areas on national roads in Ambon City based on the 2019

Equivalent Accident Number (EAN) value are roads:

Jenderal Soedirman, Jalan Pierre Tendean, Wolter

Monginsidi, Laksdya Leo Wattimena, and Ir. M. Putuhena.

Restricting movement (road medians build) intended to

limit preparing vehicles movement, turning or cutting

roads, and providing median openings at several points.

Apart from restricting movement, the median existence

also reduces vehicle speed significantly because it tends to

low speed if there is no maneuvering area.

It necessary to make openings in the residential area to

regulate the attraction movement, but they are placed in a

limited manner. Append a crossing facility of a zebra

crossing and completing it with refuge in the road median

part. Complete the traffic signs installed with a sign that

reads "Accident-prone." Append pedestrian facilities,

sidewalks, and zebra crossings at road crossings. Place a

protective fence to protect pedestrians. They are

completing additional road markings on the roadside.

Acknowledgments

We appreciated Mr. Jon Sudiman Damanik, Head of

Maluku National Road Implementation Center (BPJN

Maluku), and Mr. Yanto Apul Sirait, Head of Planning and

Monitoring Section of BPJN Maluku.

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Study on Using Fly Ash for Fly Ash - Soil Piles in Reinforcing Soft Ground

Tuan Anh Nguyen1,*, Dat Thanh Nguyen2, Tung Thanh Pham3, Linh Truong Chau3

1Transportation Engineering Faculty, Ho Chi Minh City University Of Transport, No 2. Vo Oanh St., Ward 25, Binh Thanh Dist., Ho Chi Minh City, Vietnam

2Civil Engineering Faculty, Ho Chi Minh City University of Transport, No 2. Vo Oanh St., Ward 25, Binh Thanh Dist., Ho Chi Minh City, Vietnam

3Bridge and Road Construction Engineering, University of Science and Technology, The University of Da Nang, No. 54 Nguyen Luong Bang St., Khanh Hoa Bac Ward, Lien Chieu Dist., Da Nang City, Vietnam


Cite This Paper in the following Citation Styles (a): [1] Tuan Anh Nguyen, Dat Thanh Nguyen, Tung Thanh Pham, Linh Truong Chau , "Study on Using Fly Ash for Fly Ash - Soil Piles in Reinforcing Soft Ground," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1074 - 1085, 2020. DOI: 10.13189/cea.2020.080534.

(b): Tuan Anh Nguyen, Dat Thanh Nguyen, Tung Thanh Pham, Linh Truong Chau (2020). Study on Using Fly Ash for Fly Ash - Soil Piles in Reinforcing Soft Ground. Civil Engineering and Architecture, 8(5), 1074 - 1085. DOI: 10.13189/cea.2020.080534.


Abstract Currently, the construction technology on soft ground reinforcement is very developed, including the technology of constructing soil-cement piles for soft soil reinforcement which is technically and economically effective and widely used. Another technology is using fly ash waste from thermal power plants to make fly ash- soil piles for soft ground reinforcement, which not only takes advantage of local materials but also reduces environmental pollution from operating thermal power plants. This paper introduces some research results on fly ash content and pile diameter when reinforcing soft ground. The authors modeled the calculation diagram of the soft ground reinforcement under the roadbed with the case of the hypothetical pile diameter D = 40cm; 50cm; 60cm corresponding to the content of fly ash 35%, 40%, 45%, the pile length L = 8m to handle all soft ground layers. The results show that when the pile length L = 8m, pile diameter D = 60cm corresponding to the fly ash content of 45%, the stability coefficient of K = 1.992 is larger than the allowable stability coefficient [K] = 1.4. In this case, the largest settlement strain S = 0.17m, meeting permissible settlement strain of the ground [S] = 0.3m. These results provide basement for the design, construction and operation management units to propose solutions to maximize the working ability of the materials, enhance the stability of the roadbed during exploitation.

Keywords Fly Ash-Soil Pile, Soft Ground, Reinforce Soft Ground, Roadbed Treatment, Physical Model, Numerical Model

1. IntroductionCurrently, the construction technology of soft ground

reinforcement is very developed, including the technology of constructing soil-cement piles for soft soil reinforcement which is technically and economically effective and widely used [1, 4, 26]. Fly ash waste (blast furnace ash) from thermal power plants can be used to produce fly ash-soil piles instead of soil-cement piles to reinforce soft ground. Therefore, studying on fly ash content and fly ash- soil pile diameter when reinforcing is very necessary and practical. [3,5,27]

According to the World of Coal Ash Conference (WOCA), 42.1% of fly ash is reused in the US, 90.9% in Europe, 96.4% in Japan, 67.1% in China, 13.8% in India, and 66.5% in other Asian countries, etc. [14].

In Europe, fly ash from thermal power industry is used as an additive in concrete mixes (29.5%), raw materials for Portland cement production (26.9%), and materials for roads construction and leveling (19%), etc. [14].


In 2013, Japan recorded that 12.5 million tons of ash and slag were discharged. In which, the majority of ash and slag (65.6%) were used for cement production, 5.6% used as leveling materials, and 4% used as reinforcement materials. China generated 440 million tons of ash, of which about 67% was reused. In India, the amount of fly ash discharged was 165 million tons, of which about 62.5% was reused. India used 41.2% of the fly ash as raw materials for cement production, 11.83% of waste for leveling, 6% in road construction and the rest was used as an additive to concrete, unburnt brick, ... [17].

Davidovits (1988) [6] studied that an alkaline activated fly ash mixture could harden within a few hours at normal temperature (about 30°C), within several minutes when heated to 85°C and within seconds if subjected to microwaves. The compressive strength of this material will increase over time up to about 28 days, being similar to that of using Portland cement. Compressive strength can be 20MPa after four hours at 20°C, while compressive strength after 28 days is in the range of 70-100MPa.

Davidovits [7,8] published a study on the ratios of molecules that make up fly ash cement material to obtain the products of high strength durability: the M2O/SiO2 ratio is 0.2-0.48; the ratio of SiO2/Al2O3 is 3.3-4.5; the water/M2O ratio is 10-25; the ratio of M2O/Al2O is 0.8-1.6 (where M is the alkali metal).

Balo [2] conducted experimental studies of the mechanical and thermal conductivity of the materials created by mixing wasted fly ash, clay, epoxide palm oil and renewable materials. These studies show that the higher ratio of both fly ash and epoxide palm oil, the lower the coefficient of thermal conductivity, weight, and tensile - compressive strength of the experimental samples.

Lin Wuu [11,12] conducted a 1:1 scale experiment and numerical analysis on a high-speed rail substrate to evaluate the effectiveness of the piles underneath this ground which is made of gravel, fly ash and cement. The research results show that this pile works effectively and is suitable for completely decomposed granite soil.

Na Li et al. [13] studied consolidation properties of coastal cement soil when adding appropriate amount of fly ash. The analysis results show that, when the cement content is 20%, the fly ash content is 0%, 5%, 10%, 20%, 30% respectively, and water content is 80%, the ability to withstand compression of this material increases significantly.

Haibin Wei [16,17] studied the solution of treating fly ash and oil shale ash by combining with mud clay. When applying this solution, the elastic modulus and stress state of the soil are significantly affected, leading to destruction of the initial structure and increase soil porosity.

Wang [15] conducted several studies on the swelling and stress properties of 16 types of mixtures made of cement, fly ash and lime. These studies show that the type of adhesive and the adhesive content have a great influence on the strain modulus, compressive strength, destructive strain and destructive mode, shape and position of stress curves.

Kuan [10], Xiao [18] studied the application of fly ash as an additive in soil improvement of construction works. When soft coastal clay is mixed with fly ash, the strength is significantly improved, the plasticity index and the compressive index decrease by 69% and 23% respectively.

This paper analyzes the performance of fly ash-soil piles at different diameters and different fly ash content in order to propose the most reasonable solution for soft ground treatment and reinforcement with fly ash-soil piles.


2.1. Physical-mechanical Criteria of Fly Ash-Soil Pile

2.1.1. Physical-Mechanical criteria of fly ash To determine the physical and mechanical properties of

fly ash, 2.5 tons of fly ash samples were taken. Random samples were taken uncontinously from the silo storage of Duyen Hai thermal power plant. After that, the authors selected 3 random sample groups to experiment with mechanical - physical - chemical parameters of fly ash.

The experimental results were analyzed at Quatest 2 laboratory by the method of infrared spectroscopy analysis. Two control samples were carried out at the laboratory of Road Technical Centre No. 3 by chemical and calcination methods. The average results are shown in Table 1.

According to TCVN 10302:2014: Base ash is ash with CaO content greater than 10%, symbol: C

Table 1. Fly ash test results

No Test criteria Test method Unit Result

1 Humidity [22] % 0.26

2 Porous mass density kN/m3 9.4

3 Density [23] kN/m3 22.1

4 Fineness (percentage of passing 0.08mm sieve) [23] % 2.1

5 Loss after burning [24] % 8.27

6 Content of SiO2 [24] % 81.6

7 Content of Fe2O3 [24] % 81.6

8 Content of Al2O3 [24] % 81.6

9 Content of SO3 [25] % 0.49

10 Content of CaO [25] % 12

2.1.2. Physical-mechanical criteria of soft ground

The technical criteria of the soil layers are determined according to the Report on the results of engineering geological survey of the new urban area located in the east of Mau Than street, Tra Vinh city, Vietnam.

From the current ground to the survey depth (HK1: 20m, HK2: 40m), there are 06 soil layers. The distribution depth of each layer in the boreholes is shown in Table 2.

1076 Study on Using Fly Ash for Fly Ash - Soil Piles in Reinforcing Soft Ground

Table 2. Technical properties of soil layers in boreholes

Layer Soil name Thickness (m)

HK1 HK2 1 Small sand, poor texture 1.4 1.8

2 Mud clay mixed with sand - melted state 1.1 6.8

3 Small sand, poor texture 2.9 2.8

4 Mud clay mixed with sand - melted state 8.6 20.8

5 Mixed clay, melted state - 1.4

6 Clay, elastic hard to semi-hard state - 6.4

2.1.3. Physical-mechanical criteria of fly ash- soil material

a) b)

Figure 1. Sample fabrication process and conducting the test a) Test sample of compressive strength; b) Test of total strain modulus

a) b)

Figure 2. Sample fabrication process and shear resistance test Sample for shear resistance; b) Shear resistance test

Experimental samples are made at different fly ash content from 35%, 40%, 45% to test the following parameters: Compressive strength, splitting tensile strength, determining the modulus of total mono-axial confined compression test, shear resistance, elastic modulus (Fig. 1 and Fig. 2).

2.1.4. Results

Test results of soil - fly ash mixture with the reinforcement content of 35%, 40%, 45% fly ash are synthetized at Table 3, 4, 5 respectively.

Table 3. Test result of soil - fly ash mixture with content of 35%

No Test criteria Test method Unit Test result

7 days 14 days 28 days 56 days

1 Compressive strength [19] MPa 0.108 0.208 0.28 0.32

2 Monoaxial Confined compression [20] MPa - - - 1.33

3 Elastic modulus [21] MPa - - - 102













Based on the above test results, we can graph the relationship between the fly ash content in reinforcement and the sample strength growing over time as Fig. 3.


Figure 3. Relationship between fly ash content for reinforcement and sample compressive strength develops over time

2.2. Numerical simulation on Plaxis V8.2

2.2.1. Calculation Cases The reasonable distance of piles according to TCVN

10304:2014 is from (1.5÷6)D, normally from (1÷3)D. The authors chose the distance between the piles as follows: 3.75D for d400 piles, 3D for d500 piles and 2.5D for d600 piles. The purpose of the study is to find the relationship between the reinforcement ratio with the stability and settlement of the construction; therefore, only changes resulted from pile diameter are recorded;

Researches of Khoi and Linh (2013) [9], Zygmunt Meyer and Piotr Cichocki (2020) [28] show that the

diameter has a significant impact on the load capacity of the pile. The completely treated length pile is 8m, calculated based on the calculated settlement area, and fully treated depth of the soft ground.

Case 1: Change of pile diameter: D400, D500, D600. Case 2: Change of fly ash content: 35%, 40%, 45%;

2.2.2. Results

A. In case of D600-35% fly ash piles, the distance between 2 piles is 1.5m

When reinforcing D600 - 35% fly ash piles, the result obtained as Figs. 4-6.


Figure 4. The displacement of the roadbed on soft ground when reinforcing D600 - 35% fly ash piles (Maximum settlement of the road foundation S= -0.245m)

Figure 5. Location of dangerous slip surface of roadbed on soft ground when reinforcing D600 fly ash pile - 35% fly ash


Figure 6. Stability coefficient against sliding of the roadbed on soft ground when reinforcing D600 -35% fly ash piles (K = 1.872)

B. In case of D600-40% fly ash piles, the distance between 2 piles is 1.5m When reinforcing D600 - 40% fly ash piles, the result obtained as Figs. 7-9.

Figure 7. The displacement of the roadbed on soft ground when reinforcing D600 - 40% fly ash piles (Maximum settlement of the road foundation S = - 0.172m)


Figure 8. Location of dangerous slip surface of roadbed on soft ground when reinforcing D600 - 40% fly ash pile

Figure 9. Stability coefficient against sliding of the roadbed on soft ground when reinforcing D600 - 40% fly ash piles (K =1.899)

C. In case of D600-45% fly ash piles, the distance between 2 piles is 1.5m When reinforcing D600 - 45% fly ash piles, the result obtained as Figs. 10-12.


Figure 10. The displacement of the roadbed on soft ground when reinforcing D600 - 45% fly ash piles (Maximum settlement of the road foundation S= -0.170m)

Figure 11. Location of dangerous slip surface of roadbed on soft ground when reinforcing D600 - 45% fly ash piles


Figure 12. Stability coefficient against sliding of the roadbed on soft ground when reinforcing D600 - 45% fly ash piles (K = 1.922)

2.2.3. Discussion

A. Stability coefficient Stability coefficient according to calculations [K] = 1.4 is synthetized as table 6.

Table 6. Result of stability coefficient

Stability coefficient

35% fly ash 40% fly ash 45% fly ash D400 1.584 1.723 1.872 D500 1.666 1.836 1.899 D600 1.762 1.881 1.922

The diagram of the relationship between the stability coefficient according to the pile diameter and the reinforced fly ash content is shown in Fig. 13.

Figure 13. Diagram of relationship between stability coefficient and fly ash content

Through the chart of the relationship between the stability coefficient K with the pile diameter and fly ash content, it is shown that the larger the pile diameter is and the higher the fly ash content is, the higher the stability coefficient K is.

In terms of technical aspects, the author proposes to choose piles with diameter D = 60cm, pile length L = 8m with fly ash content of 45% for the most optimal coefficient of K.

(Not reinforced)


Figure 14. Diagram of relationship between stability coefficient K and size of cement-soil pile

Comparing with the research results of [9] on stability coefficient K, this research shows that when using the fly ash- soil pile with the same diameter of D600 and the fly ash content is 45%, the stability coefficient K is higher than that of a soil-cement pile (Fig. 14).

B. Roadbed settlement Calculation results of the roadbed settlement are synthetized at Table 7.

Table 7. Calculation results of the roadbed settlement

Roadbed settlement (m)

35% fly ash 40% fly ash 45% fly ash D400 0.362 0.311 0.252 D500 0.348 0.243 0.219 D600 0.245 0.172 0.170

The diagram of relationship between settlement by pile diameter and fly ash content reinforced is illustrated in Fig. 15.

Figure 15. Diagram of relationship between pile settlement and reinforced fly ash content


Through the chart of relationship between the settlement S with pile diameter and fly ash content, we notice that the larger the pile diameter is, and the higher the fly ash content is, the lower the settlement is.

For D400, D500 piles, when reinforced with fly ash content of 35%, the settlement is not guaranteed compared with the permissible limit settlement, when the fly ash content increases to 40%, 45%, the construction settlement is smaller than the permissible limit settlement. These results prove that the settlement of the building decreases gradually when we increase the pile diameter and fly ash content.

In terms of technical aspects, the author proposed to choose piles with diameter D = 60cm, pile length L = 8m with fly ash content of 45%, resulting in the most optimal settlement S.

3. Conclusions Mechanical and physical properties, material

characteristics used in the topic are taken directly from the experiment.

When designing the project without reinforcement of the fly ash -soil piles, the displacement at the bottom of the roadbed is too large, thus, it is clear that the roadbed needs treatment. The author modeled the calculation diagram of soft ground reinforcement under Mau Than roadbed with the assuming pile diameter D = 40cm; 50cm; 60cm corresponding to the content of fly ash 35%, 40%, 45%, the pile length L = 8m to handle all the soft soil layers.

Thereby, it is able to analyze the performance of fly ash-soil piles at different diameters and fly ash content. With the pile length L = 8m, pile diameter D = 60cm corresponding to the fly ash content of 45%, the stability coefficient is K = 1.992 which is greater than the allowable stability coefficient [K] = 1.4. The largest settlement strain in this case S = 0.17m ensures allowable settlement deformation of the ground [S] = 0.3m.

Through the conversion of stress, displacement, deformation values and so on from the reduced model to the actual model, design and construction consultants and operation managers can use this model as a basis to offer solutions to ensure the construction stability during its operation duration.

REFERENCES [1] An, C.N. Foundation, Ho Chi Minh National University

Publisher, 2002.

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[7] Davidovits. Properties of Geopolymer Cements, The proceeding First International Conference on Alkalie Cements and concretes- pp 131 -139, 1994.

[8] Davidovits, J. Geopolymer Chemistry and Application. 2nd edn, Institut Geopolymere - Saint- Quentin, France, 2008.

[9] Le Van Khoi, Chau Truong Linh (2013). Study on application of embankment reinforced soil-cement piles combined with traffic roads of Kien Giang river, Quang Binh province. Transportation Journal, No.12, pp.35-41, 2013

[10] Kuan-Yeow Show, Joo-Hwa Tay; and Anthony T. C. Goh. Reuse of Incinerator Fly Ash in Soft Soil Stabilization, Journal of Materials in Civil Engineering, Volume 15 Issue 4 - August 2003.

[11] Lijun Wu. Performance of Geosynthetic-Reinforced and Cement-Fly Ash-Gravel Pile-Supported Embankments over Completely Decomposed Granite Soil: A Case Study. Advance in Material Science and Engineering, Volume 18, 11 pages, 2018.

[12] Lijun Wu, Guanlu Jiang, Nengpan Ju. Behavior and Numerical Evaluation of Cement-Fly Ash-Gravel Pile-Supported Embankments over Completely Decomposed Granite Soils. International Journal of Geomechanics, Volume 19 Issue 6, 2019.

[13] Na Li et al. Compression Characteristics and Microscopic Mechanism of Coastal Soil Modified with Cement and Fly Ash. Materials, Volume 12, 18 pages, 2019.

[14] Thuy N.B.T. Study on using waste Fly Ash in subgrade construction. Master’s thesis, Hochiminh City University of Transport, 2020.

[15] Wang, D.X.; Zentar, R.; Abriak, N.E. Durability and swelling of solidified/stabilized dredged marine soils with Class-F fly ash, cement, and lime. J. Mater. Civ. Eng. 30, 04018013, 2018.

[16] Wei H.B. et al. Experimental research on resilient modulus of silty clay modified by oil shale ash and fly ash after freeze-thaw cycles. Applied Sciences 2018, 8, 1298. 19 pages, 2018.

[17] Wei, H.B.; Zhang, Y.P.; Cui, J.H.; Han, L.L.; Li, Z.Q. Engineering and environmental evaluation of silty clay modified by waste fly ash and oil shale ash as a road subgrade material. Constr. Build. Mater. 2018.

[18] Xiao, H.W.; Wang, W.; Goh, S.H. Effectiveness study for fly ash cement improved marine clay. Constr. Build. Mater.


157, pp. 1053-1064, 2017.

[19] Vietnamese Standard TCVN 9403-2012, Stabilization of soft soil- The soil cement column method, 2012.

[20] Vietnamese Standard TCVN 4200-2012, Soils - Laboratory methods for determination of compressibility, 2012.

[21] Vietnamese Standard TCVN 9483-2013, Standard test method in the laboratory for resilient modulus of nonorgannic adhesive substance stabilizied aggregate material, 2013.

[22] Vietnamese Standard TCVN 7204-2013, Portland cement clinker, 2013.

[23] Vietnamese Stanrdard TCVN 4030:2003: Cement - Test method for determination of fineness, 2003.

[24] Vietnamese Stanrdard TCVN 8262:2009: Fly ash - Methods

of chemical analysis, 2003.

[25] Vietnamese Stanrdard TCVN 141:2008: Portland cement - Methods of chemical analysis, 2012.

[26] Martin Tazky, Rudolf Hela, "High-Performance Concretes Intended for Deep Foundations of Constructions," Civil Engineering and Architecture, Vol. 8, No. 2, pp. 46 - 54, 2020. DOI: 10.13189/cea.2020.080202.

[27] Mochamad Solikin, Alfian Nur Zaini, Budi Setiawan, Ali Asroni, "Flexural Strength Analysis of Styrofoam Concrete Hollow Panel Walls Incorporated with High Volume Fly Ash," Civil Engineering and Architecture, Vol. 8, No. 3, pp. 320 - 325, 2020. DOI: 10.13189/cea.2020.080316.

[28] Zygmunt Meyer, Piotr Cichocki, "Analysis of Combined Pile Raft Foundations Based on a Static Load Test," Civil Engineering and Architecture, Vol. 8, No. 2, pp. 101 - 112, 2020. DOI: 10.13189/cea.2020.080208.


DOI: 10.13189/cea.2020.080535

Study on Response of G+5 Symmetric Structure

Subjected to Blast Loads

I Krishna Chaitanya1,*, Balaji K. V. G. D2, M. Pavan Kumar3, B. Sudeepthi4

1Research Scholar, GITAM (deemed to be University) and Department of Civil Engineering, Raghu Engineering College, Visakhapatnam, 531162, India

2Department of Civil Engineering, GITAM (deemed to be University), Visakhapatnam, 530045, India 3Department of Civil Engineering, SVP Engineering College, Visakhapatnam, 530041, India

4Research Scholar, GITAM (deemed to be University) and Department of Civil Engineering, Raghu Engineering College, Visakhapatnam, 531162, India

Received September 9, 2020; Revised October 13, 2020; Accepted October 30, 2020


(a): [1] I Krishna Chaitanya, Balaji K. V. G. D, M. Pavan Kumar, B. Sudeepthi , "Study on Response of G+5 Symmetric

Structure Subjected to Blast Loads," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1086 - 1094, 2020. DOI:

10.13189/cea.2020.080535.

(b): I Krishna Chaitanya, Balaji K. V. G. D, M. Pavan Kumar, B. Sudeepthi (2020). Study on Response of G+5 Symmetric

Structure Subjected to Blast Loads. Civil Engineering and Architecture, 8(5), 1086 - 1094. DOI:

10.13189/cea.2020.080535.


Abstract There is a need to study and design blast

resistance structures as the terrorist activities are increasing

day by day for all important structures. In present day

scenario, accidental or intentional blast may take place at

any point of time. From the recent blast in India at

Pulwama in 2019, Bogota city in Colombia 2019 and

Mogadishu city in Somalia 2018, there was a huge loss for

human life. Hence, it is vital to understand how structures

behave when they experience blast loads. In this paper the

effects and behavior of a G+5 symmetric Reinforced

concrete building with surface blast for three different

charge weights of 500, 1500 and 2500 kg TNT (Tri nitro

toluene) assuming that the blast has occurred from a range

of 10, 15 and 20 meters in lateral direction and analysis was

done using SAP 2000 considering on the positive phase of

the blast. Based on the results obtained from the study,

response for variations in inter storey drift and energy

absorbed by the considered structure is studied.

Keywords Blast Load, Time History Analysis, Lateral

Displacement, Inter Storey Drift, Energy Absorbed

1. Introduction

Study on Blast effected structures has become a

technical inspection and investigation, as almost from

1920-2019 there are more than 500 blast attacks had been

occurred by source cars and trucks and from the recent

blasts of Bogota city in Colombia 2019, Pulwama in 2019,

and Mogadishu city in Somalia 2018, many buildings are

collapsed and many people were killed. A catastrophic

damage to the buildings externally and internally by

collapsing wall is caused when blast explosion occurs

within or nearby structures. There will be huge loss of life

and many injuries to the residing people due to structural

collapse, impact by debris, smoke along with fire. Due to

these gas-chemical explosions, a large dynamic load more

than the designed original loads considered on the structure

will be obtained and this has become a most important

consideration and challenge for designers by the global

attacks. As conventional buildings are not designed to

resist blast loads as we cannot scale the impact of blast as it

is a sudden attack. But however, we can try to understand

the performance of the structure at the time of blast from

the past history and with the maximum blast impact data

and can adopt new guidelines for the constructed structures

and new structures too.


Nelson et al., [1] conducted time-history analysis on

mailto:[email protected]

https://en.wikipedia.org/wiki/Pulwama

https://en.wikipedia.org/wiki/Colombia

https://en.wikipedia.org/wiki/Mogadishu

https://en.wikipedia.org/wiki/Somalia

https://en.wikipedia.org/wiki/Colombia

https://en.wikipedia.org/wiki/Pulwama

https://en.wikipedia.org/wiki/Mogadishu

https://en.wikipedia.org/wiki/Somalia


simple cantilever model walls, developed a capacity

spectrum model for analyzing of blast loads for cantilever

wall subjected to linear elastic dynamic analysis based on

the function of blast pressure, and identified the correlation

between clearing time and corner period of the blast.

Van der Meer [2] using ANSYS11.0 investigated the

dynamic response of structures for BLEVE blast loading

and blast loading to determine the mode shapes and natural

frequencies. Maximum displacement is obtained at the top

in static analysis. Using SDOF and MDOF method, the

pressure impulse diagram and response diagram are

procured for BLEVE blast loading when applied to a

sample building and the base shear response, top

displacement base moment is compared.

Mohamed S. Al-Ansari [3] investigated the response of

structures to earthquake and blast loads. Blast loads of

1000 kg of TNT are applied on a six-story building at a

distance of 2 m. When an earthquake load in zone 5 is

applied to a twenty- story building and analyzed, it showed

similar response like it is blasted with 128 kg of TNT at a

range of or 261 kg of TNT at a range of 10 m.

Jayashree et. al [4] investigated the dynamic response of

a space framed structure when it is exposed to a blast load

using SIFCON by performing time history analysis for

blast loads by employing SAP 2000. The results show that

about 20-30% of reduction in displacement is obtained by

adopting SIFCON.

Aditya Kumar et al., [5] has studied different loadings

which occur during a blast and the methods used to

investigate these loading phenomena. The study show that

the lack of relevant code is the main reason for not adopting

this phenomenon in designing the structure.

Quazi Kashif and M. B. Varma [6] studied the evolving

different methods of design and structural analysis for

resisting blast loads by considering a 5 storey building and

the model was created using SAP 2000. A standoff of 30 m

from explosion blast effect is calculated. Lateral load is

computed and compared in terms of inter storey drift,

Velocity accelerations and peak deflections showed that,

performance level of building is reached to collapse Point

for minimum standoff distance

Sarita Singla et al., [7] studied blast pressures for blast

loads and ranges, using U.S manual, for different

conditions are calculated for blast pressures by taking the

interrelationship between scaled blast distance and blast

pressure. With the conditions of duration of positive phase

of blast and reflected total over pressure time history

loading are calculated, the results reflect that the blast

pressure reduces as the distance increases from the

building.

Swathi ratna k [8] conducted a study on RCC and

Simcon buildings when subjected to blast effects using

time history analysis to compute the dynamic response of a

structure to an arbitrary loading in ETABS. From the study

it has been concluded that SIMCON buildings have much

more fundamental frequency than RCC buildings.

M Pavan Kumar and K. Rambabu [9] The intent of this

paper is to explore the response of RC Space Frame with

vertical setback to earthquake and blast loading using

Applied Element Method (AEM). From this result, it was

observed that for 2500kg TNT blast load the maximum

X-displacement and earthquake load are proportionate at

all storeys.

Jinwon Shin and Kyungkoo Lee [10] have studied the

deficiencies of SDOF design charts for near field

detonations for high explosions and also investigated the

consideration of uniformly distributed load for SDOF

analysis for near field detonations. To solve these problems

upgraded SDOF design charts which include the response

to the nearfield detonations based on numerical

calculations are suggested and are compared to finite

element analysis results of steel component and UFC

3-34002 predictions and are verified accordingly.

Boyina sita Rama Krishna and Jinka Chandra Sekhar [11]

studied the effects of blast loads on G+10 RCC structure,

subjected to blast load of 10kg TNT at a range of 30m

which is designed in SAP 2000 using nonlinear time

history analysis. The results are calculated for storey drift

and maximum storey displacement. It was deduced that the

performance of structure joints were critical when they are

close to the blast and hence Hinges are developed in all

beams and columns.

Pavan Kumar and K. Rambabu [12] The aim of this

work is to study the behavior of Regular RC Space Frame

subjected to Earthquake and Blast loads using Applied

Element Method (AEM). It is noticed from the results that

for 2500 kg TNT blast load maximum X-Displacement and

Earthquake load were equivalent at all storeys. At a

duration of 5 seconds the maximum displacement occurred

of a frame subjected to Northridge earthquake whereas it

occurred at 0.5 seconds of a frame subjected to 2500kg

TNT blast load.


3.1. Geometry of Considered Structure

A G+5 Reinforced concrete frame building having size

22m x 22m is considered with equal bay width of 5.5m and

storey height of 3m. Geometry details of the considered

building as shown in (figure 1).

3.2. Cross Section Details of the Structural Components

Following are the cross-section details of various

structural components of the considered building

Plinth beam size : 230mm x 230mm

Floor beam size : 230mm x 500mm

Column size : 450mm x 450mm

Slab thickness : 150mm

1088 Study on Response of G+5 Symmetric Structure Subjected to Blast Loads

3.3. Material Properties

Grade of concrete : M30

Grade of steel : Fe415

(a) Plan

(b) Elevation

c) 3D Isometric view

Figure 1. (a,b,c) Geometry views of the considered building

3.4. Details of Loads

Initially, analysis and design were performed on the

considered building subjected to gravity loads (Dead and

Live). Blast load is applied on the designed frame (as per

IS:456-2000) to study the response of the structure.

3.5. Blast Loads

Surface blast load on structure for intensities of 500,

1500 and 2500 kg TNT at different ranges of 10, 15 and 20

m are calculated based on TM-5-1300. Typical view of

frame with different charge weights and ranges are shown

in the (figure 2).

(a) For a range of 10 m

(b) For a range of 15 m

(c) For a range of 20 m

Figure 2A. (a,b,c) Typical view of frame with different charge weights

and ranges


(a) At 10 m range

(b) At 15 m range

(c) At 20 m range

Figure 2B. (a,b,c) Plan view showing the placement of the blast with

different charge weights and ranges

3.6. Analysis

Time history analysis is performed on the considered

Reinforced Concrete structure subjected to various surface

blast load intensities at different ranges using SAP 2000

software package.


4.1. Response of Structure for Blast Load of 500 kg

TNT at a range of 10, 15 and 20 m

4.1.1. Lateral Displacement

The variation of lateral displacement of the structure

against blast load of 500 kg TNT at 10, 15 and 20 m at

different storey levels are shown in (figure 3).

(a) At 10 m range

(b) At 15 m range

(c) At 20 m range

Figure 3. (a,b,c) Lateral Displacement vs Time for 500 kg TNT charge

weight at range of 10, 15 and 20 m

4.1.2. Inter storey drift

From (figure 3), maximum inter storey drift is calculated

for each storey of the considered structure for a charge

weight of 500 kg TNT at a range of 10,15 and 20 m. To

know the response of the structure for 500 kg TNT blast,

graph is plotted between ratios of maximum inter storey

drift of standoff distance 15m to 10m / 20m to 10m vs

storey level.

Figure 4. Inter storey drift ratios vs storey level for 500 kg TNT charge

weight


For a charge weight of 500 kg TNT, it is clearly

observed from figure 4 that maximum inter storey drift

ratio between standoff distances 15m to 10m and 20m to

10m is found at a storey level of 6m. For a standoff

distance of 15m and 20m, there is a decrease in maximum

inter storey drift at every storey level when compared to

10m standoff distance.

4.1.3. Acceleration

The variation of acceleration of the considered structure


different storey levels are shown in the (figure 5).

(a) At 10m range

(b) At 15m range

(c) At 20m range

Figure 5. (a,b,c) Acceleration vs Time for 500 kg TNT at 10, 15 and

20m ranges

4.1.4. Energy absorbed

From the theory of Arias intensity (IA = 𝜋

2𝑔ʃa2 dt) which

determines the intensity of shock wave by measuring the

acceleration of seismic waves. Inspired from this theory,

Pavan et al. [13] proposed (ʃa2 dt) to determine energy

absorbed by the structure against blast. The same theory is

used in this study. From the acceleration data obtained

from the analysis at a storey level of 3m against a blast load

of 500 kg TNT at 10,15 and 20 m ranges, graph is plotted

between the energy absorbed by the structure vs time as

shown in (figure 6).

Figure 6. ʃa2 dt vs time for 500 kg TNT at 10, 15 and 20 m range

From the (figure 6), for a charge weight of 500 kg TNT,

blast-initiated time for 15m standoff distance is twice that

of 10m standoff distance, whereas 20m is thrice that of

10m standoff distance. Maximum energy absorbed by the

structure for 10m standoff distance is 10 times more than

15m standoff distance and 20 times more than 20m

standoff distance. Maximum Energy absorbed by the

structure for all the considered standoff distances is within

0.1 seconds.

4.2. Response of Structure for Blast Load of 1500 kg






(a) At 10m range

(b) At 15m range


(c) At 20m range

Figure 7. (a,b,c) Lateral Displacement vs Time for 1500 kg TNT charge

weight at range of 10, 15 and 20 m


From (figure 7), maximum inter storey drift is calculated

for each storey of the considered structure for a charge

weight of 1500 kg TNT at a range of 10,15 and 20 m. To

know the response of the structure for 1500 kg TNT blast,


drift subjected to blast load for 15m to 10m / 20m to 10m vs

storey level.

Figure 8. Inter storey drift ratios vs storey level for 1500 kg TNT charge

weight




10m is found at a storey level of 6m. For a standoff distance

of 15m and 20m, there is a decrease in maximum inter

storey drift at every storey level when compared to 10m

standoff distance.

4.2.3. Acceleration

The variation of acceleration of the structure against

blast load of 1500 kg TNT at 10, 15 and 20 m at different

storey levels for the considered building are shown in

(figure 9).

(a) At 10m range

(b) At 15m range

(c) At 20m range

Figure 9. Acceleration vs Time for 1500 kg TNT at 10, 15 and 20 m

ranges

4.2.4. Energy absorbed

From the acceleration data obtained from the analysis at

a storey level of 3m against a blast load of 1500 kg TNT at

10,15 and 20 m ranges, graph is plotted between the energy

absorbed by the structure vs time as shown in (figure 10).

Figure 10. (ʃa2 dt) vs time for 1500 kg TNT at 10, 15 and 20 m range

From the (figure 10), for a charge weight of 1500 kg

TNT, blast-initiated time for 15m standoff distance is 1.75

times that of 10m standoff distance, whereas 20m is 2.75

times that of 10m standoff distance. Maximum energy

absorbed by the structure for 10m standoff distance is 10

times more than 15m standoff distance and 20 times more

than 20m standoff distance. Eighty-six percentage of total

energy absorbed by the structure is absorbed within 0.1

seconds only for all the considered standoff distances.


4.3. Response of Structure for Blast load of 2500 kg






(a) At 10m range

(b) At 15m range

(c) At 20m range

Figure 11. (a,b,c) Lateral Displacement vs Time for 2500 kg TNT

charge weight at range of 10, 15 and 20 m


From (figure 11), maximum inter storey drift is

calculated for each storey of the considered structure for a

charge weight of 2500 kg TNT at a range of 10,15 and 20 m.

To know the response of the structure for 500 kg TNT blast,


drift subjected to blast load for 15m to 10m / 20m to 10m vs

storey level.

Figure 12. Inter storey drift ratios vs storey level for 2500 kg TNT

charge weight




10m is found at a storey level of 6m. For a standoff distance

of 15m and 20m, there is a decrease in maximum inter

storey drift at every storey level when compared to 10m

standoff distance.

4.3.3. Acceleration

The variation of acceleration of the structure against

blast load of 2500 kg TNT at 10, 15 and 20 m at different

storey levels are shown in (figure 13).

(a) At 10m range

(b) At 15m range

(c) At 20m range

Figure 13. Acceleration vs Time for 2500 kg TNT at 10, 15 and 20m

ranges


4.3.4. Energy Absorbed

From the acceleration data obtained from the analysis at

a storey level of 3m against a blast load of 2500 kg TNT at

10,15 and 20 m ranges, graph is plotted between the energy

absorbed by the structure vs time as shown in (figure 14).

Figure 14. (ʃa2 dt) vs time for 2500 kg TNT at 10, 15 and 20 m range

From the (figure 14), for a charge weight of 2500 kg

TNT, blast-initiated time for 15m standoff distance is 1.75

times that of 10m standoff distance, whereas 20m is 2.5

times that of 10m standoff distance. Maximum energy

absorbed by the structure for 10m standoff distance is 10

times more than 15m standoff distance and 20 times more

than 20m standoff distance. Eighty-five percentage of total

energy absorbed by the structure is absorbed within 0.1

seconds only for all the considered standoff distances.

5. Conclusions

The structure affects significantly when there is

increase in charge weight and with decrease in

standoff distance.

For a charge weight of 500 kg TNT maximum inter

storey drift for 15m and 20m standoff distance is 41%

and 30% of 10m standoff distance respectively.

For a charge weight of 1500 kg TNT maximum

inter storey drift for 15m and 20m standoff distance

is 77% and 58% of 10m standoff distance

respectively.

For a charge weight of 2500 kg TNT maximum

inter storey drift for 15m and 20m standoff distance

is 79% and 68% of 10m standoff distance

respectively.

Maximum acceleration in the considered structure

is observed at a storey level of 3m for all the

considered surface blast loads.

Energy absorbed by the considered structure

subjected to charge weight of 1500 kg TNT is 2.5

times more than that of same structure subjected to

charge weight of 500 kg TNT

Energy absorbed by the considered structure

subjected to charge weight of 2500 kg TNT is 3.5

times more than that of same structure subjected to

charge weight of 500 kg TNT.

The blast-initiated time of considered structure for

15m and 20m standoff distance is more than that of

same structure with 10m standoff distance

subjected to different charge weights.

Almost eighty percentage of energy absorbed by

the structure is within 0.1 seconds time for all the

considered blast loads.

REFERENCES

[1] Nelson Lam, Priyan Mendis and Tuan Ngo, Response Spectrum Solutions for Blast Loading, Electronic Journal of Structural Engineering, (2004).

[2] L. J. Van Der Meer, Dynamic Response of High-Rise Building Structures to Blast Loading, Research report, Eindhoven University of Technology, A-2008.8, April (2008).

[3] Mohamed S. Al-Ansari, Building Response to Blast and Earthquake loading, International Journal of Civil Engineering and Technology (IJCIET), Vol. 3, Issue 2, ISSN: 0976 – 6316 pp. 327 – 346, July - December (2012).

[4] Jayashree S.M, Dynamic Response of a Spaced Framed Structure Subjected to Blast Load, Journal of Civil and Structural Engineering, ISSN: 0976 – 4399, Vol. 4, Issue 1, Aug (2013).

[5] Aditya Kumar Singh, Md. Asif Akbari and P. Saha, Behavior of Reinforced Concrete Beams under Different Kinds of Blast Loading, International Journal of Civil Engineering Research. ISSN: 2278 – 3652, Vol. 5, No. 1, pp. 13 – 20 (2014).

[6] Quazi Kashif and M. B. Varma, Effect of Blast on G+4 RCC Frame Structure, International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459, Volume 4, Issue 11, November (2014).

[7] Sarita Singla, Pankaj Singla and Anmol Singla, Computation of Blast Loading for a Multi-Storeyed Framed Building, International Journal of Research in Engineering and Technology, e-ISSN: 2319 – 1163, p-ISSN: 2321 – 7308, (2015).

[8] Swathi ratna. K, Analysis of RCC and simcon buildings subjected to blast effects, international journal of civil engineering and technology 223–233 pp. Article ID: IJCIET_07_04_018 ISSN Print: 0976-6308 and ISSN Online: 0976-6316, , Volume 7, Issue 4, July-August (2016).

[9] M Pavan Kumar and Rambabu k, Performance of RC space frame with vertical set back subjected to seismic and blast load using applied Element method, Disaster advances 10(5):1-13, May (2017).

[10] Jinwon Shin and Kyungkoo Lee, Blast Performance Evaluation of Structural Components under Very Near Explosion, KSCE Journal of Civil Engineering, pISSN 1226-7988, eISSN 1976-3808, June 14,(2017).

[11] Boyina sita, Rama Krishna and Jinka Chandra Sekhar, blast load analysis and effect on high rise structures, pp. 340–347, International Journal of Civil Engineering and Technology, Article ID: IJCIET_09_06_039, ISSN Print: 0976-6308 and ISSN Online: 0976-6316, Volume 9, Issue 6, June (2018).


[12] M Pavan Kumar and Rambabu k, response of regular RC space frame subjected to seismic and blast load using applied element method, Disaster advances 11(7):17-28, July (2018).

[13] M. Pavan Kumar, G.K. Chaitanya, K. Rambabu, “Collapse

Analysis of R.C Buildings subjected to Blast Load using AEM”, The 18th International Symposium on New Technologies for Urban Safety of Mega Cities in Asia (USMCA – 2019), 9th –10th December 2019, Yangon Technological University, Yangon, Myanmar.


DOI: 10.13189/cea.2020.080536

A Design Proposal of Integrated Smart Mobility

Application for Travel Behavior Change

towards Sustainable Mobility

Gülce Kırdar1,*, Sabiha İrem Ardıç2

1Faculty of Architecture, Istanbul Technical University, 34367, Istanbul, Turkey 2Faculty of Architecture, Middle East Technical University, 06800, Ankara, Turkey



(a): [1] Gülce Kırdar, Sabiha İrem Ardıç , "A Design Proposal of Integrated Smart Mobility Application for Travel

Behavior Change towards Sustainable Mobility," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1095 - 1106,

2020. DOI: 10.13189/cea.2020.080536.

(b): Gülce Kırdar, Sabiha İrem Ardıç (2020). A Design Proposal of Integrated Smart Mobility Application for Travel

Behavior Change towards Sustainable Mobility. Civil Engineering and Architecture, 8(5), 1095 - 1106. DOI:

10.13189/cea.2020.080536.


Abstract The private car dependency is prevalent due

to its comfort, privacy, and convenience. However, it is

challenging for the cities in environmental and economic

aspects. The widespread car use arises from the urban

network and land use pattern besides peoples' personal

preferences. The study's concern is reducing car

dependency. The study questions "how to empower

behavior change with the use of smart mobility applications

for sustainable mobility." The study aims to promote travel

behavior change by leveraging technology through an

integrated smart system design proposal, which is entitled

Sustainability Aware Travel Service (SATS). SATS offers

a smart mobile application for the citizens and a connected

data platform for the decision-makers. The SATS platform

bridges these different actors: the app aggregates the user

travel data, and the data platform monitors user data to

support mobility-related decisions. The paper presents a

conceptual framework of this system. This paper aims to

contribute to existing smart mobility applications by

promoting active mobility modes, cycling, and walking.

Keywords Sustainable Mobility, Travel Behavior

Change, Smart Mobility Applications, Urban Data

Platform

1. Introduction

The mobility preferences of people mainly depend on

driving in the cities. Private car use is preferable due to its

comfort, privacy, and convenience. Apart from personal

preferences, the condition of transportation infrastructure

and mobility services are influential in private car use. The

private car use has overgrown considerably during the last

decades. According to the World Business Council for

Sustainable Development (WBCSD) report, cars have 69%

of all km traveled in Europe [1]. Private car use increased

by 20% in the past 20 years [1]. Increasing car use poses a

threat to sustainability. According to the International

Energy Agency, the transportation system is responsible

for 30% of total energy-related carbon dioxide emissions

[2]. The agency predicts that the percentage can rise to 50%

by 2030 and 80% by 2050 unless taking precautions [3].

The car use causes pollution, high costs of travel, loss of

time in traffic, and lack of user experience of an urban

environment. Based on these outcomes, the study describes

private car use as a vital problem for the cities. These facts

underline the significance of sustainable mobility modes.

Sustainable mobility enables the movement with minimal

environmental and territorial impact while satisfying travel

needs. Benevolo and other colleagues [4] point out that

smart technologies play a significant role in the travelers'

attitude towards mobility choices. The research aims to

1096 A Design Proposal of Integrated Smart Mobility Application for Travel Behavior Change towards Sustainable Mobility

explore the ways of encouraging people to other sustainable

mobility modes, instead of car use. The study questions

"how to support users' behavior change and policymakers'

strategy to promote users' QoL in mobility with the use of

smart mobility applications." This research seeks to

contribute both to user's travel behavior change and

policymakers' mobility strategies.

A considerable amount of literature is available on smart

mobility. Based on the literature review, there is a gap in

intelligent services that serve both citizens policymakers'

demands. This gap creates a need for an integrated

application that provides communication between the

stakeholders, planners, and citizens on the same platform.

This paper presents a conceptual design of a smart mobility

service, entitled as SATS, which stands for Sustainability

Aware Travel Services. The SATS combines an application

and platform in an integrated service. The SATS adopts a

user-centric approach to the decision-making process of

urban design. The motivation of the SATS is to improve

citizens' quality of life by changing travel behavior and

support decision-makers' decisions.

According to the study, travel behavior change is the

driver, and quality of life is the outcome for sustainable

mobility. People have to change travel behavior to perform

sustainable mobility, and sustainable mobility improves the

quality of life of individuals. Smart initiatives have the

potential to raise user awareness on travel attitude.

Therefore, the literature review urges upon these following

questions:

How to achieve behavior change;

What are the parameters of QoL related to mobility;

How to improve QoL with behavior change;

What is the state of the art in smart mobility;

How the relevant studies foster the design of SATS?

1.1. Behavior Change Towards Sustainable Mobility

for QoL

Regarding the sustainable mobility strategies [5], the

research concentrates on shifting the demand towards

sustainable travel modes with the use of smart technologies.

Banister [5] points out that its applicability depends on the

understanding and acceptance of individuals. This section

investigates the points to achieve behavior change with

smart applications.

Cinderby and other colleagues [6] state that the bottom-

up approach with personalized social marketing empowers

the individual to make an informed choice. As a result,

users reduce car use and increase cycling for travel [6].

Besides the bottom-up approach, continuous support for

personal travel planning activities is essential for long-term

behavior change [7]. Congratulating the users with updated

changes, and challenging them to pursue travel behavior

with the prize system can be the actions for ongoing support.

Another factor in sustaining behavior change is positive

behavioral support. The quality of life is a shared value that

provides this behavioral support [8]. The quality of life

(QoL) is 'the people's perceptions of life quality concerning

their culture and value systems [9]. The modern lifestyle

decays individuals’ QoL due to inactive behavior

dominance. The focus of this study is the mobility and

health related QoL parameters, listed below:

Environmental quality (average exposure to air

pollution and land use factors);

Personal health status (illness rate and life

expectancy);

The work-life balance (the duration of commuting);

Mobility (travel mode and ticket price).

This study utilizes ICT to raise awareness aiming to shift

travel behavior towards sustainable mobility modes. The

use of ICT has a vital impact on managing travel activities

and peoples' mobility behavior [11]. The ICT supported

smart mobility services contribute to a reduction in

congestion, accidents, within vehicle-dependent air

pollution and noise. Among smart mobility systems, MaaS

stands for mobility as a service. MaaS offers tailored

mobility packages and additional services such as real-time

planning, reservations, and payments for different transport

modes [12]. MaaS aims to provide 'door-to-door mobility'

for users' [12].

This research analyses several MaaS applications. This

analysis reveals that the existing MaaS applications are

district and disconnected systems. For instance, the user

utilizes different MaaS applications for different services,

such as pricing and timetable information, payment, and

journey planning. They lack presenting extensive

customization options. The user has to utilize different

applications to exploit mobility services.

Regarding the drawbacks of existing MaaS programs,

SATS seeks to combine the services in one application

program. Thus, the user can access many options in one

application instead of using different services. The study

suggests that integrating a MaaS application with an urban

data platform would be useful for both users and

policymakers. This integrated application makes a bridge

between users and planners in sustainable mobility.

Urban data platforms engage citizens with stakeholders.

The data platforms utilize many datasets from multiple

sources to provide a holistic view of the city's functioning

[13]. They perform as data aggregators by gathering

multiple datasets under a single roof [14]. Tuncer and You

[14] denote that these platforms create an interface as a

strategic step for smart governance. They allow developing

data-driven methodologies for informed urban

management. Reference [13] categorize the levels of

insights provided by platforms:

Critical insight for recommendations;

Analytical insight for patterns;

Strategic insight for decisions.

Operational insight for urban characteristics.


1.2. State of Art in Smart Mobility

Thus far, this paper explains the scope and goals of the

data platforms. This section reviews the existing data

platforms. The study limits the examples with Km4City

and Informed Design Platform focusing on user-data.

Tuncer and You [14] develop a data platform named

'Informed Design Platform (IDP)' as a part of the Livable

Places project. The IDP platform adopts a data-driven

approach to provide insight into livable public spaces [14].

The platform utilizes the usage pattern and perceptions of

the crowd. It includes multi-sourced data concerning place,

time, and people concepts, categorized in utilization,

activity, opinion, and sensing parameters [14]. As another

example, the researchers from Distributed Systems and

Internet Technologies Laboratory (2015) develop a

knowledge model for the city (Km4City) [15]. Nesi and

others [15] state that Km4City brings a new approach to

smart city APIs. The platform combines open data from the

administration, private data coming from users and

transportation system managers, and manage static and

dynamic data. The objective of the Km4City platform is to

support decisions about city infrastructure management.

The platform measures and monitors the citizens'

movement flow in parking and transportation hubs [15].

The existing data platforms mainly concentrate on

processing statistical data. The studies that consider

people's tendencies and routines about travel behavior are

rare. Km4City takes the user data as input; however, it lacks

displaying the trends of the crowds. The study distinguishes

with its user-intrinsic data coming from the use of the app.

The study deals with the social aspects of sustainable

mobility by monitoring users' travel behavior patterns.

The researchers conduct a literature review to respond to

the questions indicated in the previous section. The points

for long-term impact are implementing personalized social

marketing strategies, providing ongoing support with

updated services, and positive behavior support. The

enhancement of the quality of life is the outcome of the

study. The study uses smart mobility services as a tool to

alter users' travel behavior. For positive behavior support,

the SATS application can involve a recommendation

system. The system recommends according to the users'

preferences. The user can get information about their

financial savings, personal health benefits, and

environmental benefits when they change travel behavior.

The SATS application's objective is twofold: First, the

SATS encourages people to change their travel behavior

considering sustainability to improve their life quality

through the smart app. Second, the app's connection with a

data platform supports policymakers' mobility decisions in

long-term.


The SATS is a model for the combination of an

application and an urban data platform. Therefore, the

methodology of the SATS system follows in two separate

branches; the conceptual design of the SATS application

and the SATS urban platform. Figure 1 is a workflow

diagram that displays the general framework for two

branches of the system. As shown in the workflow diagram,

the SATS system's output becomes an input for the

platform. Both two parts consist of data collection, analysis,

user interaction, and representation stages. SATS seeks to

target both the citizens and policymakers by improving the

QoL of individuals and supporting policymakers' decision-

making in mobility. Regarding two different target groups,

the system will have three types of interaction, which are

user-application, user-platform, and policymaker-platform

interaction.

This study will be conducted in Istanbul. Istanbul suffers

from traffic congestion. The INRIX publishes Global

Traffic Scorecard report that represents the mobility trends

and traffic congestion in the major cities of the world.

Based on the results of INRIX [16] report, Istanbul is

ranked as the 4th worst city in terms of traffic congestion,

with a 6% increase. People spent approximately 157 in

traffic in 2019. Other reason of why Istanbul is selected

derives from the low well-being performance indicator, and

unsatisfactory conditions in quality of life survey research

conducted by OECD [17]. A series of researches has been

conducted about mobility pattern analysis in the case of

Istanbul. The research studies are intended for assess the

relationship between user travel time and trip number,

traveled with motorized vehicles [18]; between residential

status and travel behavior [19]; travel demand indicators

and urban form by comparing different cities [20]. There

are also a series of reports about mobility strategies in

Istanbul, which are organized by institutions or non-profit

organizations (NGOs). For example, Smart Mobility Public

Transport Report [21] presents the roadmap of Istanbul for

smart mobility; while Sustainable Urban Mobility Report

[22] examines the mobility condition in Istanbul

considering other demographic, geographic, economic and

legal parameters. The SATS proposal seeks to contribute

the strategies of supporting sustainable and healthy choices

and promoting to use active mobility mode, as indicated in

[21]. It also aims to support the quantitative evaluation of

users’ mobility pattern by monitoring it in its platform.

2.1. Conceptual Design of SATS Application and

Platform

The motivation for designing the SATS application

comes from people's increasing tendency to use social

media and carry smartphones. The key concerns in smart

mobility applications are making people aware of their

mobility behavior by displaying the impact of their actions

on the environment, their financial budget, or time spent

traveling. What differs SATS from relevant applications is

that it gives more information about QoL and other


motivation factors to stimulate sustainable mobility. It

gathers user data in the platform's database with user

permission for long-term behavior support. Table 1

displays the expected features of the SATS application.

We identify the guidelines for data collection, data flow

and process, and user interface to draw a conceptual

framework. For data collection, we determine what type of

data is collected by the developer, and what kind of data

obtained from the application used as input. Regarding the

dimensions of QoL, the required input data is described

based on the travel modes. We gather the primary data from

relevant institutions, while the secondary data through the

APIS and crowdsourcing. The data flow stage describes

how to transform input data to output via the application

and transmit it to the stakeholders, as shown in Figure 1.

The system will perform the following tasks to process

information; travel planning, different travel options based

on travel modes and traffic, and journey evaluation,

assisting in generating a mobility database based on user

travel patterns and preferences. In user interface design, we

determine the criterion expected to meet, as following:

Figure 1. Conceptual Design of the SATS System (drawn by authors).

Clear for simple user interaction;

Consistent and well-structure to ease the use;

Flexible for interoperability with other smart

devices;

The convenient interface design for user-friendliness;

The use of color palette that evokes the

sustainability.

While the existing data platforms focus on evaluating the

physical and spatial quality of the urban environment, the

SATS platform will monitor users' travel prefer. Instead of

the time and cost-intensive surveying methods for data

collection in travel behavior, the platform aims to collect

data through the application automatically. The SATS

platform acts as a bridge between decision-makers and

users: it aggregates the user data from the mobile app. It

visualizes to support decision-makers in terms of

sustainable mobility. The study's contribution is to exploit

smart technology to understand the citizens' travel behavior

aiming for long-term behavior change. The study

hypothesizes that the platform might have a long-term

impact on changing individuals' travel behavior towards

sustainable mobility by creating awareness on users and

assisting policymakers for user-centric informed decisions.

The SATS platform's motivation is implementing a data-

driven approach to understand and analyze user behavior in

terms of sustainable mobility.

The study hypothesizes that the platform might have a

long-term impact on changing individuals' travel behavior

towards sustainable mobility by creating awareness on

users and assisting policymakers for user-centric informed

decisions. The SATS platform is developed, aiming to:

Find out what factors are more influential for

behavior change;

Monitor to what extent the user changes the travel

behavior and how long to observe the behavior

change;

Understand how the application influences

individuals' behavior and how it contributes to

sustainability.

The SATS platform consists of three main elements; (i)

an information model that integrates multiple data types (ii)

an interface with control panel, dashboard for information

visualizations (as diagram and graphics), and (iii) an

interactive map that shows spatial information. SATS

platform will be an online, interactive, open-sourced, and

web-based mapping platform. Additionally, the platform

would be user-centric, flexible, and open. Openness means

being accessible through public APIs and having open-

source content open to development. Flexibility means

leveraging from different programming languages such as

Python, R, and SQL to develop the platform.

2.2. Data Collection

For data collection, we integrate different input data

types derived from both user and developer; therefore, we

categorize the input datasets as user input datasets and

developer input datasets. The first dataset consists of the

user travel mode preference, commuting travel patterns,

user travel data (kcal, produced CO), GPS traces, the rates,

and comments within images. We plan to obtain the user

data via the SATS smart mobile application. These data

types are unstructured data and mainly based on qualitative

data. The second dataset consists of the road network,

infrastructure, station and charging stations, the timetable,

traffic density, existing air quality. These data types are

structured and mainly based on quantitative data. The

database is categorized according to the dimensions of QoL

indicators, as stated in the OECD [9] framework.

Regarding the aspects of QoL, Table 2 describes how the

system functions in terms of data management


Table 1. The Features of the SATS Application (drawn by authors)

Application SATS - Sustainability Aware Travel Services

Scheme (Area) and Status (Year) Istanbul / Development phase (2019 - …)

Transport modes related services

Public transport (including local transport modes)

Walking paths

Bike-sharing

Car sharing, including e-cars

Parking places

Charging stations

Platform & Tariff option Application and website

Pay-per-use

Available functionalities

Real-time information / Trip planning / Booking (and cancellations if needed)

Ticketing / Payment /Service alerts

Informing about quality of life as an individual/ Database for policymakers

Virtual budget / Physical activity diary

Type of actors involved

Service aggregator

User of technologies

Public and private actors

Third-party

GPS / e-Pay

Personalization

Input personal address, preferable transport modes

Store regular and preferred (favorite) routes / Store tickets

Saved (often visited) locations

Optimized travel plan based on user's daily agenda (through agenda synchronization) and most

environmentally friendly

Customizations

Enable route accessibility for people with special needs

Enable mode filtering based on cost, CO2 footprint and the calories burned

Identify the benefits of improving your QoL


Table 2. The input datasets and output information for the data platform

2.3. Data Analysis

We implement data mining techniques to obtain useful

information from different data sources. Data mining is the

synthesis of statistics, machine learning, information

theory, and computing to generate evidence-based insight

into decision making [22]. The data mining process

consists of three main stages; (1) data preparation, (2) data

analysis, (3) evaluation of patterns, and interpretation as

knowledge [23]. Data mining stages are inserting,

classifying, clustering, and associating to reveal the hidden

relations between datasets. In data preparation, we

transform the multi-source unstructured data into

structured numerical data frames. The semantic data-

derived from the comments- can be enumerated through the

sentiment analysis. The ranking data can be evaluated with

a graded system, using a grading scale of 1-5, with a

ranking algorithm [24]. We analyze the metadata of photos

to evaluate the popularity of routes. These different input

data, which comes from the application, are connected with

their geo-location. We organize datasets based on their

spatio-temporal information (coordination, date & time)

and create a database. Then, we will apply the clustering

algorithm to classify datasets based on their

interdependencies. K-means and DBSCAN are two of the

most used clustering algorithms. DBSCAN stands for

density-based spatial clustering of applications with noise.

K-means is a distance-based clustering technique; while,

DBSCAN is density-based. These clustering analysis

methods depend on distance between the points. The

CATEGORIES INPUT OUTPUT

BY DEVELOPERS BY USERS DATA TYPE & MAPPIND INTO

FOR POLICYMAKERS(THROUGH THE PLATFORM)

FOR USERS(THROUGH THE APPLICATION)

1. Mobility

1.1. Passive Mobility

public transportation public transportation

services network (GIS & OPM)

choice of public transportation

selecting journey type (single/daily commute)

ranking public transportation qualitydemands such as public transportation services for time table, location of stops

review and comments

Map the GPS traces and find the location

based clusters

map of the public transportation preferences and

the most used network

show the ranks/ reviews and demands for public transportation services

decision support for improvement and satisfaction of the road conditions

travel planning based on traffic and public transportation conditions

cost & time estimation for transit travel mode

Shows the quality of public transportation according to specific parameters

comparison between the public transportation and other travel modes in terms of cost, health and air

quality

locations of the stops and timetables of public transportation

the travel expenses of public transportation services

traffic condition(Google Maps/ Yandex traffic services)

Car - sharing system & electric car

road network (GIS&OPM) -Choice of car-sharing system-Ranking car-sharing services according to specific parameters-Demand for locations of new car-sharing points-Ranking electric car services according to specific parameters-Demand for locations of

new electric stations and parking lots

Map the GPS routes,reviews Categorize based on rakings in grading scale

-Map the most used car-sharing and electric car network and ranking its quality-Map the car-sharing demand within the routes and rankings -Map demand for locations of new electric stations and parking lots -Display the reviews

-Decision support for improvement of the electric car services -Decision support for improvement of the car-sharing system

-Travel planning for car-sharing system based on traffic condition and rankings -Cost calculation based on the fuel/gas per km & electric use per km-Shows the car-sharing quality and electric car quality based on the rankings

-Comparison between the electric car use, car-sharing systems and motor vehicles in terms of cost, health and air quality

traffic condition(Google Maps traffic services)

locations of car-sharing points & gas/fuel stations

locations of electric stations and parking lots

cost of the use of car-sharing system fuel/ gas per km

cost of the electric per km

1.2. Active Mobility

Cycling/ electric bike

Bike sharing system

cycling road network (GIS) -Choice of cycling/ bike sharing and electric bike

-Ranking the cycling experience according to specific parameters

-Ranking bike sharing and cycling quality (with images and reviews)

-Demand the locations of new bike parking lots/ new bike-sharing stops and electric charge stations

Map the GPS routes,reviews Categorize based on

rakings in grading scale

-Map the most used cycling route and most visited

bike parking lots

-Show the demand for locations of new bike parking lots and routes, bike-sharing parkings and routes

-Display the reviews

-Decision support for improving the physical infrastructure and promoting the use of bicycle within the bike-sharing systems

-Travel planning for cycling based on the rankings

-Show the cycling quality and bike-sharing system performanceaccording to specific parameters

-Comparison between cycling and other travel

modes in terms of cost, health and air quality

locations of bike parking lots

locations of bike-sharing points

cost of the bike-sharing per hour

cost of the bike-sharing per hour

locations of electric stations

cost of the electric per km

Walking street network (GIS)street views (Google Earth)

choice of walking

Ranking the walking experience according to specific parameters (with images and reviews) Map the GPS routes,

reviews Categorize based on rakings in grading scale

-Map the most used cycling route and most visited bike parking lots -Show the inadequencis and demands in physical infrastructure and physical elements-Display the reviews -Decision support for improving the physical infrastructure and urban environment for walkability

Suggestions of different routes

Travel planning for walking

Shows the walking quality according to specific parameters

Comparison between walking and other travel modes in terms of cost, health and air quality

2. Work-life Balance

Duration of commute road network within land use (GIS) tagging the home and working place (GPS tracing and travel time)

ranking of the commuting time between home-work


Display the most used commuting time between home-work

Decision support for new employment area considering commuting time

Show the commuting time between home-workDisplay the most preferred commuting network for each area

3. Health Status

Lung disease related effect of air pollution on diseasesair quality map road network

user health condition (related with lung disease) (optional)


-Map the lung disease distribution for each area

-Map the most active zones based on user preferences

-Decision support for population health issues

-Calculation the amount of effect on diseases according to different travel modes-Calculation the consumed calori in whole travel (based on walking and cycling distance)-The amount of decreased risk of obesity in case of walking and cycling

-Personal physical activity diary-Comparative analysis between different travel modes in terms of physical acitvity

Personal health data /

obesity risk related

consumed cal per m

according to the type activity

Height

WeightFat Percentage (optional)

4. Environmental quality

Air quality quantity of air pollution produced by fossil powered motor vehicles

users' travel mode choiceMap the GPS routes,reviews

Categorize based on rakings in grading scale

Map the air pollution change

Decision support for decreasing air pollution

Calculation of produced air pollution by users' preferences for each travel

Comparative analysis between different travel modes in terms of air pollution

the air quality map


research will employ the K-means clustering analysis

method, which basically divides n observations into k

clusters to decrease the square error objective function

where d is the distance between the data point and the mean

of the cluster [25], as shown in Equation (1).

∑𝑘𝑗=1 ∑𝑛

𝑖=1 (𝑑𝑗𝑖)

2 (1)

We apply the K-means clustering method to find the

clustered pattern in the neighborhoods. Further, we apply

the gravity-based population-potential model on the

clusters to explain the relations based on distance and

population of the neighborhoods. Gravity models are the

mathematical formulations to analyze and predict the

spatial interaction models [26].

The types of gravity models are (1) origin-based, (2)

destination-based and (3) network or potential models [19].

The potential models measure the network of relation

between places, illustrated by potential surface maps.

Ravenstein adapts the gravity model, based originally on

Newton’s gravity law, to social sciences first to measure

the migration patterns [26]. Equation 2 both describes the

gravity model and gravity potential model. In the gravity

model, whereI ij is the interaction between places i and j, k

is a constant, Pi and Pj are measures of the size of places i

and j (e.g., populations), dij is the distance between places

i and j, and b is the friction of distance. In the gravity

potential model, where Vi is the population potential of

place i , M j is the population of j, and dij is the distance that

separates place i and j [26]. Here, we take the most used

GPS traces as input for distance and the active user number

for population of the location.

𝐺𝑖𝑗 = 𝐺 𝑀𝑖 𝑀𝑗 𝑑𝑖𝑗2⁄ 𝑉𝑖 = ∑ 𝑀𝑖 /𝑑𝑖𝑗) (2)

We plan to use Phython and R programming tools for

data analysis and visualization. Weka and RapidMiner are

the other effective programs for data mining.

2.4. Data Mapping and Visualization

The study employs a Web-GIS environment for data

mapping. It is an advanced form of Geospatial Information

System available on the web platform and allows users to

manage all their geographic data. GIS environment works

commonly with vector data (geometrical data) in shape-file

format raw data in structured CSV file format. By

structuring the metadata into CSV file format with its geo-

coordinates, other types of data (text, image) can be used in

a GIS environment to provide spatial information. We will

process the relational databases in a programming

environment (such as Java code or R) for data visualization.

In further steps, the study seeks to benefit from the existing

GIS-based maps. The SATS platform interface includes the

following components:

A control panel (on the top) that allows selecting

the analysis measures,

The analysis results of the parameters (on the left),

Interactive map (in the middle),

A dashboard for the information panel (on the right)

displays the selected zone's statistical data as visual

information (Figure 2). 2.5 SATS System

Interactions

This paper examines the general framework for the

interaction between the target groups and the SATS system

under three categories: user-application, user-platform, and

policymaker-platform.

Figure 2. The interface of the SATS platform (drawn by authors).

2.4.1. User-Application Interaction

The application interacts with the user in six stages. First,

creating a user profile is to start to use the app. The users

define user profile information, while other input data such

as height, weight, and fat percentage are optional. There is

an option to add friends from the existing users or inviting

via a link. This feature of the application aims to promote

the use and create a commune awareness in society. In

terms of privacy settings, they could have public, private,

or semi-public profiles. The public profile is open to every

user, semi-profile is open to friends, and personal profile is

closed to anyone. The options of creating a virtual budget

and physical activity diary customize the use of

applications according to users' activity and budget to

provide personal spaces aiming to sustain the behavior

change. The user can control their travel expenses with a

virtual budget to observe daily & monthly costs and savings.

In a physical activity diary, the users' physical activities can

be tracked daily & monthly and saved automatically.

Second, planning a journey presents two types of travel:

a single trip and a daily commute. For a single trip, origin

and destination points are necessary. If they search for a

daily commute, they need to save their home, work, or

school locations. They can also define the time range for

their daily commute.

Third, selecting an option presents users the sustainable

mobility choices to promote behavior change. There will be

six different options, including different travel modes for

the same journey. The six categories are determined as

follows: i- user-friendly, ii- cost-friendly, iii-social friendly,

iv- environment-friendly, v- time-friendly, and vi-health


friendly according to users' priorities. There will be brief

information about categories such as time, cost, emission

level, and consumed energy. When one of the options is

selected, brief information will be given (including time,

travel expenses, emission level, and energy). The system

generates different routes for each travel chosen mode. For

instance, for a cost-friendly option, the user will get

financial-weighted information, and the travel options will

be generated based on cost, time, and energy. The priority

of the information and parameters determining the routes

shows variation according to the selected option. The ways

differ based on travel mode. The system recognizes urban

spatial quality for walking and cycling, the service capacity,

the number of public transportation changes, and

congestion and air quality for car use. For instance, in

selecting private car use or car sharing, the user can be

informed about the air pollution level in the zones by

choosing different routes.

The fourth step is to rate the journey after completed.

The reason for the evaluation stage is gathering data for the

platform and investigating the reasons behind the users'

travel behavior. According to the travel modes' selection,

the app displays different parameters to rank are physical

and personal parameters:

The quality of transportation infrastructure, the

timetable of public transportation, the convenience

for walkability and cyclability, land use pattern;

Information quality of the service, Journey

experience, safety, time, and cost-efficiency.

We rank the survey options according to selected travel

modes: public transportation, car-sharing, electric car,

bike-sharing, electric bike, cycling, and walkability. The

system allows including comment or photo regarding the

journey. These comments and images will be informative

to evaluate the trip's experience and the quality of the urban

platform.

Figure 3. SATS Application Interface (drawn by authors).


The fifth feature is receiving notifications about the

SATS platform. The users' travel preferences, marks,

comments, and images will be input for the platform, and

policymakers will develop their strategies according to

these analyses. We plan to deliver general information

about transportation, health conditions of the society, or

annual reports about the air quality to the users via the

notifications. We aim to show the users that their decisions

and feedback could play an essential role in policymakers'

decisions. The last feature is checking the homepage. The

notifications and news edited by developers and decision-

makers, the friends' actions, and all information will be

available on the homepage. With those options, we aim to

create social interaction between the SATS and users and

increase public awareness in terms of sustainable mobility.

Figure 3 displays the particular stages of interaction via the

application interface.

2.4.2. User-Platform Interaction

The user can engage with the platform both via mobile

application and web application. The platform gives

information about urban mobility situations based on

identified QoL parameters: mobility, commute, health, and

environmental quality. In the mobility parameter, the user

can get information about the public transportation network,

timetable, and cost. The users can decide which

transportation mode would be more efficient in terms of

health, travel expense, and time by comparing transit

modes. The platform displays the problematic or preferable

road segments, based on the users' comments and rankings.

For the active-mobility modes selection (cycling and

walking), the platform shows the benefits of active mobility

in terms of cost, health, time, and air quality with graphs

and statistics in the dashboard. The users can monitor each

neighborhood's ranking score; thus, their awareness level

of mobility can increase. For the commuting parameter,

each user can observe their commute time and work-life

balance diagrams. The data can be compared with other

users' outputs anonymously to see the effects of travel

mode choices on their work-life balance. In the health

parameter, the users can observe the ranking of road

segments in terms of air quality and create their healthy

route based on the rankings. They can also create a personal

physical activity diary, which measures the decrease in risk

of obesity via walking and cycling, and compare the impact

of different travel modes on physical activity. In the

environmental quality parameter, the map of air

pollution of each zone from the interactive map will be

available. Besides, this parameter would be useful for

vulnerable groups who suffer from lung disease. In contrast,

the other group of users can see the percentage of the risk

of lung-related diseases derived from air pollution. Figure

4 displays the user interface of the SATS platform.

2.4.3. Policymaker-Platform Interaction

The platform enables policymakers to implement a data-

driven approach during the decision-making process in

terms of mobility. The platform's output information

mainly assists in developing transportation-related urban

systems decisions based on the identified QoL parameters.

In the mobility parameter, the policymaker can monitor

the condition of the transportation system and services, and

user travel patterns, within preferences. By observing the

user travel pattern, we plan to identify the factors that affect

behavior change to promote active mobility.

The factors can show differentiation according to the

characteristics of the neighborhood. For instance, for the

region with low income, the cost-effectiveness can be the

primary driver for behavioral change. On the other hand,

for a business district, time efficiency can be the primary

driver; accordingly, the transportation strategy can be more

time-efficiency oriented in these areas. These outcomes

show the importance of customization of the

neighborhoods. Moreover, we plan to monitor citizens'

demands on physical infrastructure, stations, the condition,

and quality of the public transportation system, the quality

of the built environment via the platform. The user ranking

can help to detect the road network and infrastructure

elements that need to be improved. The high rated routes

could be a role model for the improvements. With the help

of the commuting parameter, the policymaker can track

the commuting pattern of the citizens. We plan to identify

the traffic congestion based on the user commuting routes.

In the long term, this parameter can assist policymakers in

making decisions in the new employment area. From the

health parameter, the planners can gather information

about the distribution of vulnerable groups in the city and

direct transportation decisions considering this or

concentrate clean mobility strategies, particularly in these

regions. In the environmental quality parameter,

policymakers can analyze the vehicle-related air pollution

density. They can detect the risk area in terms of air

pollution. They can prepare developers' annual reports in

terms of mobility, and develop the long-term mobility

strategies based on the annual report. Besides data

monitoring and decision support, the platform allows

policymakers to include the notifications about the new

developments in transportation services and feedback on

the comments and demands of citizens. This feature opens

up opportunities in citizen-governance and participation.


Figure 4. The User Interface in Health and Environmental Quality Parameters (drawn by authors).

3. The Expected Results

We elaborate on the project's expected results in three

main aspects: behavioral change of the people towards

more sustainable mobility, increase in quality of life, and

decision support system for urban planning. It is expected

that individuals' travel choices can change towards

sustainable mobility with the SATS system. This system

can promote ongoing support, which is vital to maintain the

behavioral change for long-term benefit, with its

notifications and customized application use. The expected

results are a decrease in air pollution, noise pollution, and

CO2 emission in terms of environmental quality. In terms

of health status, the expected results are an increase in

people's daily physical activity level and a decrease in their

fat percentage. An expected reduction in air pollution

derived from carbon-based transportation will provide

more fresh air, especially for people suffering from

respiratory diseases, which are lung cancer, asthma, or

bronchitis. In terms of work-life balance, we foresee a rise

in productivity in the workplace due to less commuting

time and more physical activity.

We also expect an increase in cost-time efficiency in

daily commute journeys. In terms of mobility, one of the

expectations is an increase in sustainable mobility modes.

We expect users to shift travel demand to lower-carbon

modes such as walking, cycling, and electric vehicles. Last

but not least, we assume that the expansion of the MaaS

with an integrated system has contribution decision

systems in urban planning by including data-driven

methodologies. Last but not least, we think that the

expansion of the MaaS with an integrated system has a

contribution to decision systems in urban planning by

adding data-driven methodologies. We believe that this

system encourages the citizens' motivation for participation

in the urban planning decisions since it allows them to

comment, rank and make recommendations on existing

built environment conditions, and follow the results of this

evaluation. We foresee clear communication between the

users and policymakers via the SATS platform. The SATS

might be a starting point for the cities to implement smart

governance in the city. The project can contribute to

scientific knowledge in the field of evidence-based urban

analysis and design. Overall, the most significant expected

result is designing and planning more sustainable

neighborhoods regarding mobility following these

contributions.

4. Discussion and Conclusions

This paper concerns the conceptual framework of the

SATS to present an innovative solution for travel behavior

change. The literature review addresses the research

questions of how to achieve behavioral change towards

sustainable mobility with ICT for increasing QoL. The

SATS system differs from the existing MaaS application

with the integrity of the application and platform. The

second difference of the SATS derives from being more

user-friendly and open to customization. The other

difference is the way of collecting information and

diversity of information content. The system will gather

user opinions via ranking evaluation, updated

simultaneously, rather than surveying methods. It will

benefit multiple data-sources for data collection ranging

from images, rankings, to reviews. The advanced options

to process various user data would be an innovative side of

the project. The ways of data processing are quantifying

comments and other user data, detecting clusters in

different data types, and mapping it according to geo-

location.

To conclude the research, the researchers discuss the

limitations and present recommendations about the project

for further studies. First of all, the prevalent use is crucial

to maximizing the benefits of the system. The developers

should be sure that people use the application because the

use rate of many MaaS applications is low. The second

point is the promotion and marketing strategies for the

application. Another point is the inclusion of sociological

and physiological reasons for people's travel behavior.

Most people consider using a car as a prestige. Lastly, the

researcher should drill down the details of computational


methods to provide the dynamic information flow between

the application and platform. This study will follow a case

study design in Istanbul. The reason is the insufficient level

in QoL measures and the high level of car-dependency,

compared to other European countries. The customization

of the SATS system to the context brings both possibilities

and limitations. For further stages, the system can be useful

both for real estate and tourism. The more ranked places in

the SATS can become the points of interest (POI). The

ranking and comment option can be useful to detect

attractive public spaces, for real estate and tourism

development. The study recommends that integrating smart

services with ambient intelligence through the sensors. The

integration of RFID technologies with the SATS app

improves the quality and accuracy of the data platform. The

data platform can monitor the activity pattern of the crowds

in real-time.

Acknowledgments

We would like to thank Associate Professor Aloys

Borgers for her helpful critics and technical coordination.

We are grateful to Jan Philipp Steffen and Nina Swelsen for

their contribution. This project is the outcome of the 'Smart

Cities' course at the Technical University of Eindhoven.

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Housing Dilemma and Vertical Dimensions

Muhiuddin Bahauddin Yusuf1, Islam H. Elghonaimoy2,*

1Researcher in Housing and Urban Design, University of Bahrain, Kingdom of Bahrain 2College of Engineering, University of Bahrain, Kingdom of Bahrain


Cite This Paper in the following Citation Styles (a): [1] Muhiuddin Bahauddin Yusuf, Islam H. Elghonaimoy , "Housing Dilemma and Vertical Dimensions," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1107 - 1118, 2020. DOI: 10.13189/cea.2020.080537.

(b): Muhiuddin Bahauddin Yusuf, Islam H. Elghonaimoy (2020). Housing Dilemma and Vertical Dimensions. Civil Engineering and Architecture, 8(5), 1107 - 1118. DOI: 10.13189/cea.2020.080537.


Abstract Bahrain is a small island suffering from land scarcity, caused by the limited land area and the overpopulation. Bahrain will face dramatic problems in all life levels due to the frequent use of horizontal urban growth. However, by observing coastal countries such as Bahrain, Singapore, Japan, etc., some governments tend to reclaim land upon the surrounding water body, to provide enough area for urban development. This results in harming the nature and disturbing the ecology of the environment. Therefore, these issues have made designers think about a solution of accommodating a large number of inhabitants with less land area; intended for a sustainable urban solution to cities and limiting the land reclamation upon the seawater cases. Moreover, the idea of this research is to focus upon building communities vertically, giving a solution for the sustainable vision issues: the natural environment, the social and the engineering elements publication.

Keywords Vertical Cities, Sustainable, City Problems, Urban Heat Island (UHI)

1. IntroductionThe Kingdom of Bahrain is expected to reach a

population of 1.592 million in the year 2020. In the year 2030, Bahrain will reach to 2.128 million (figure 1). However, the population was 621 thousand in the year of 1999. The average rate of growth is 7.4% (Ministry of Information Affairs-Kingdom of Bahrain, 2020). The demand for housing units in terms of low and medium-income families is increasing. Every year a range

of 3,000 marriages occurs, assuming that 50 % are in need for housing units; this gives a total of 1,500 houses per year (Kingdom of Bahrain - eGovernment Portal, 2019). The high density in urban areas in Bahrain is caused due to the rapid concentration of people living in a particular metropolitan area such as Manama, Riffa and Muharraq. However, with high density, destinations become more walkable and provide the opportunity of different transportations. Consequently, the aim is to find a solution, which avoids urban sprawl and combines all the needs of an individual in their life in a sustainable way to the current urbanization pattern and trends in Bahrain. Nevertheless, the fact that based on the population increases, living spaces will need to be created. However, building houses and neighbourhoods most likely results in the destruction of natural habitats. Therefore, the research hypothesis is that the Vertical Cities are the sustainable key for solving the housing demand problems in Bahrain. Hence, the research is based upon two main objectives, the theoretical and the literature reviews, as well as technical issues. The theoretical and the literature reviews discuss the urban land issues and housing demands, as well as finding a suitable approach towards urban growth. Furthermore, explore the informational depth of Vertical dimensions in solving housing problem in Cities. The technical issues will help implement the idea to real life in Bahrain. The research problems are summarized as follows.

2. Major Reasons of Housing ProblemsIn Bahrain, Urban growth is caused by the increase of

the population and due to the physical expansion of towns.

1108 Housing Dilemma and Vertical Dimensions

Consequently, Urban sprawl is related to urban growth (El-Dardiry & El-Ghonaimy, 2016). When sprawls are built, lacking smart growth planning, it causes an unsustainable environment, which forces the community to rely on automobiles for transportation and different quality of lives, resulting in an untenable situation. Smart growth is planning areas, which are near the city; one will be able to use bikes and public transportations (El-Dardiry & El-Ghonaimy, 2016).

Unfortunately, the government started to reclaim land due to the land scarcity, caused by the overpopulation. This is costing the government high expenses. Consequently, land reclamation harmed the environment and marine life Bahrain has announced seasons for fishing, as the marine life has become miserable due to the reclamation of land. The factories around the city and the lack of greenery caused air pollution (El-Ghonaimy & Javed, 2018). On the other hand, the country began to design villages with residential buildings instead of private houses; nevertheless, it still did not solve the problem as the population is increasing rapidly.

Moreover, urban areas became congestion and a high density is caused due to people living in a particular urban area. However, some urban planners vision this positively, as with high density, destinations become more walkable, and the opportunity of different transportations will exist. High density leads to higher traffic crowd (El-Ghonaimy & Mohammed, 2019).

Consequently, there is a declining Infrastructure within the urban areas, which needs comprehensive improving plans. Improved infrastructure means the improvement of public resources, such as roads and electricity, reaching everywhere around a country. However, the development in a sense and the quality of life led to the rising of standards of living. People started to be able to pay to travel more and reach distances to work. In addition, they love to live in a calm environment without the crowd and with less traffic. Therefore, man started to sprawl out, causing harm to the environment. They started to cut trees, leading to the disappearance of green areas and the constructing of poor infrastructure of roads (Nechyba & Walsh, 2004).

(cio.gov.bh, 2017, developed by Author, 2018)

Figure 1. The Rate of Area of Kingdom of Bahrain by Governorates from 2009-2013


Moreover, historically, the housing problems in Bahrain has many influences. The transformation from a Village Society to a Developed Urban Society became serious phenomena. Bahrain opened a widespread market for developments. This led to the transformation of the country from a village society to a developed urban society. However, the population has grown from 661,317 to more than 1 million in 2008. This development and movement had a negative impact. As the investors are designing plans for their own purposes, led to the creation of suburbs. Suburbs are a problem in urban designing, which is creating separate districts away from the central city. Moreover, the government started giving land with houses unconsciously to civilians, shaping the Bahraini intellect to refuse the concept of an apartment. This caused problems, as the population is increasing, they have to start reclaiming lands and building housing projects and districts. “Figure 1” is explaining numerically how the problem is overgrowing (Wiedmann, 2010).

One of the important factors that affects the housing problems is the population Increase. Bahrain opened a broad market for developments. This led to the population’s growth from 661,317 to more than 1 million in 2008. This development and movement had a negative impact (figure 2). Consequently, the Ministry of Housing, Kingdom of Bahrain provides ranged income families with affordable housing units, with an ease of payment. There is a percentage of houses for the families, who have limited income that does not own housing units. The ministry is working towards providing every family with a unit. Bahrain invested 208 million dinars into housing programs. This investment aims to provide affordable housing units and reducing the government’s housing waiting list. The vision is to provide limited income families with suitable and appropriate dwellings.

Conclusion of this part, there are significant forms of

problems are resulted. Social problems in tem of the loss of the traditional quality and the absence of the community due to the changing the residences lifestyle and the segregation between classes. An unhealthy neighborhood for social interaction and social pollution besides the scattering of life facilities and services. Moreover, different forms of pollutions such as water pollution and air pollution. Serious economic problems are resulted for the land prices especially for housing issues and energy consumption and declining in Applying Bahrain’s vision of 2030.

3. Vertical City, Sustainability and Solving the Housing Problem

Bahrain’s main goal and vision of 2030 is to build for human needs. If we accept the most significant percentage of the country’s construction is dedicated to housing, as well as, the current trends for sustainable urban development focuses on the designing of vertical communities, it is essential to explore the concepts of sustainable development and architecture. Also, the idea of community/neighbourhood, village/city, horizontal/vertical development, etc. In other words, we need to have populated settlements in vertical buildings. It is a group of permanent residence, located close to each other, enabling its people to be social and get closer to each other. A Vertical City has its specific laws towards lands, housing units, sanitation, utilities and transportations. Furthermore, to make transportation easy on foot and attract people to visit built places. Transportation systems are more straightforward compared to a city, as it is smaller in terms of land area and population. The structure has a religious centre and shops, which one can buy their basic needs (Pateman, 2011).

Figure 2. Bahrain’s Rate Increase of the Population from 2010-2015 (Data.gov.bh, 2017, developed by Author, 2018).


While talking about the sustainable architecture and a Vertical City (high-rise buildings), we have to rise the vision of creating a forming of a Community (group) of people living and working together in the same area. Sustainable architecture focuses primarily on the proper use of energy and the managing of conservation it. Moreover, it is innovative in the way of people’s living. Green architecture is part of sustainable development. This role of designing a green building will involve architecture, construction, structure, green building materials, maintenance, etc. Human development throughout the years has led them to the development of technology and medicine; this enables man to live longer and healthier lives. However, this brings a problem of the overpopulation (Al Najjar, 2018). However, those people practice different activities in their daily lives. For example, working, learning, shopping, etc. will be provided, connecting the people in the same structure (Al Najjar, 2018).

Moreover, A Vertical City has continuity, differentiation and endless circulation, giving the sense of a city, but a skyscraper or a tower is repetitive floors with vertical circulation. The vertical spaces will respect sustainability in terms of social, environmental, economic, accessibility, aesthetic, functional and sustainable issues.

a Social Character that Solving social problems via controlling the segregation, through a healthier mix of different ethnic groups and enhancing the people’s lifestyles by reducing the amount of time spent in traffic, as a result of giving them all their needs in proximity. Beside the creating healthy neighborhoods for social interaction, enhancing and forming communities and providing most of the sorts of life facilities and services in one place

In addition, the aesthetic character by creating a landmark, showing people what cities could be. Moreover, have a building, which is in top of the art in terms of material and technology, as well as a response to the climatic and the environmental factors. It will help in enhancing visual quality with providing vertical agricultural gardens.

While the economic character will help in solving the housing issues and a new way introduced to the region and giving character and meaning. It will create different spaces with different identities and providing vertical agricultural gardens, which will create job opportunities and encouraging production families within every vertical cluster, moreover, reducing the cost of transpiration, shipping and time. Moreover, the Use of eco-friendly methods in constructing and designing. Controlling the significant reasons for land reclamation

In the future, the only possible way to accommodate the rapid increase in population is by vertical living. To design a Vertical City, architects will think to combine mixed-use facilities and complexes within one building, some spaces are public, and some are private. High tech, site and

sustainability in the design is used concerning the culture. Also, thinking about the people’s need and daily life activities, according to the cultural requirements. It will have residential, commercial, educational, outdoor and public spaces. It should offer a 24-hour living center.

It should be noted that, In the plan of the year 2030, new cities and towns will be built within different areas. Therefore, the proposing of vertical cities can be part of the urban context. The vertical cities will be built, offering more residential spaces within its urban fabric. It will enhance and overcome the obstacles of the ministry of housing and works in providing the solution to the overpopulation of the citizens. It will influence positively upon the environment that Bahrain has released actions regarding environmental issues, to try to control the air pollution, climate change, water conservation, marine life and land resources. While socially, building factors, which will lead to prosperity in the community. Economically, having green solutions towards building a better economy. In addition, reducing energy consumption, clean energy technology, eliminating pollution water resource management and conservation of biodiversity.

Searching for the International Experiences in Applying Vertical Cities to have lessons, the case studies in hand are about vertical cities, which are under construction, vision or built. One of these case studies is the “Endless Vertical City”, which has richness in its components and design. The case’s components will be used in terms of the manipulation of spaces, to have the village opened to the street without obstructions, as if it is part of the horizontal urban context. Also, the exposing of services and facilities to each other. For example, the ones, which are located towards the urban streets, following the urban scheme. Moreover, there will be a sense of continuation and easiness, and public gardens will be located on every several floors within the complex. The project follows the urban ordering, but vertically. Each part will be designed individually as to represent the function based on levels so that users will have a sense of direction (Figure 3).

The other case is the Shenzhen Logistic City, which helped in understanding a vertical city, as there should be a fast vertical circulation movement between spaces. The social and spatial interactions are the highest priority, providing sunlight according to the need of the spaces; by the manipulation of spaces and the shape of the building. Creating spaces where people will interact with each other, while achieving their purpose of buying, working and living within the structure. Also, using the urban pattern and scheme (figure 4).

The last case is “De Rotterdam” which is following the urban scheme, which can be used in the project. However, going from private to semi-private to the public gradually and giving intention to the community and the social life of the occupants. Moreover, the building should be near a public transportation facility and have easy accessibility with endless design. Parking is on the ground floor


basement then comes to the offices (figure 5)

Components: a. Parking b. Commercial c. Offices d. Housing units e. Gardens, public spaces & facilities f. Educational g. Vertical circulation: ramps (Sure-architecture.com, 2015).

Figure 3. Endless Vertical City; Shoreditch, London, UK (Sure Architecture, 2015)

Components: a. Parking b. Commercial c. Offices d. Housing units e. Gardens, public spaces & facilities f. Reception Information g. Vertical circulation: tram (Yoneda, 2010)

Figure 4. Shenzhen Logistic City, Shenzhen, China (JDS Architects, 2006)

Components: a. Parking. b. Commercial. c. Offices d. Housing units e. Gardens, public spaces & facilities f. Hotel g. Vertical circulation: escalators and lifts (OMA Architects,

2013)

Figure 5. De Rotterdam located in Rotterdam, The Netherlands (OMA Architects, 2013)

Moving to the Technical Issues, some items should be considered such as:

The Structural; that the City will have a hybrid structure. It is used when creating an un-regular shape of a building. The hybrid structure will be used to achieve the building’s construction, as explained in figures 6 and 7. Different structural systems are presented in figure 6: model A represents a framed tube system, while B represents the bundled tube system, however, C represents the tube in tube system, D represents the diagonalised system, moreover E represents the core and outrigger system and F represents the hybrid system (figure 7).

Figure 6. Types of Structures (Hallebrand & Jakobsson, 2016)


Figure 7. Hybrid Structure (Rana & Rana, 2014)

(Wark & Wark, 2003, developed and drawn by Authors, 2020)

Figure 8. Extensive System

(Wark & Wark, 2003, developed and drawn by Authors, 2020)

Figure 9. Intensive System

Greenery Issues; Green spaces are a major element in designing the urban context. Green roofs are provided within the vertical city, either extensive or intensive. The motivation behind giving green territory is to mollify nature at high-density residential structures, particularly in urban regions. The ecological wellbeing will progressively get disturbed without green spaces as shown in figure 8 and 9 (Shukri & Misni, 2017).

Special Building Services; (Specialised systems) that suit high-rise buildings are the mechanical and electrical services. Those services are vertical circulations, plumbing, HVAC, firefighting, gas supply and garbage systems. They should be in smart high technology systems (Shukri & Misni, 2017). The Smart Garbage Treatment System should have a room for temporary garbage storage on each floor of the structure, as it is essential. The caretaker will take the garbage and the recyclables from the warehouse. Another more practical way is to install a garbage chute, which leads to the central garbage room at the bottom or ground floors of the building. There will be different chutes, one for the garbage and the other for the recyclable wastes. Overbearing the tremendous height of the structure, there will be transit levels every particular floor. The caretakers will upload the garbage to the service lifts to the ground floor to the garbage truck. The caretaker will empty the trash and the recyclable garbage storages located at the lower levels of the structure (Department of Environment and Climate Change NSW, 2008). Providing a chute for The Vertical City is more economical and easier (figure 10).


Figure 10. Garbage Chute Mechanism (Ecotech Chutes Pvt. Ltd., 2020, developed and drawn by Authors, 2020)

While for the HAVC, a green and smart HVAC system refer to heating, ventilating and air conditioning. It should be considered to avoid the expecting overload of the traditional methods, which saves energy. The HVAC system interacts with the lighting system in the envelope system. High-performance HVAC results in significant energy savings. It will save 30 percent reduction in the annual energy cost with a payback period of three to five years. Heating and cooling will be designed using the ASHRAE standards (City of New York Department of Design and Construction, 1999).

Moreover, for a smart vertical circulation, geared and gearless traction elevators are used in high-rise buildings, capable of high speed. Gearless motors will save up to 25 percent of energy when compared to geared motors. Another advantage of gearless engines is that it runs faster, as they have a higher torque. So gearless traction will be used in the Vertical City, preferred to be in the centre. The gearless traction elevators will be specially designed, respecting different factors to reach to the highest point. Those factors are the time of arrival of the lift, safety precautions, pressure, durability, etc. (Al-Kodmany, 2015).

Fire Precaution should be considered while designing, that foe the lower floors will have fire-rated exit staircases, with a separated structure. The fire staircase walls will have a separate structure. Nevertheless, when going to the upper floors, the structure will be equipped with different systems for emergencies; system visual monitors and emergency communication. Those systems help in guiding the people through announcements and instructions to the Occupants and non-occupants. There are elevators designed for

firefighters for rescuing. The building will use programmed enhanced lifts for emergency events and evacuations, as well as, helicopter landing area. Occupants and non-occupants on the highest floors will reach transfer floors. They will enter to the express elevators to reach to the ground floor (Kinateder, Kuligowski & Omori, 2014). However, the Fire Precaution still significant challenges while thinking about vertical cities.

In skyscrapers, plumbing as shown in figure 11 the tanks should be multi-staged to supply the sweat water to the upper floors without damages, such as damaging the pump. The water pressure transmits the water from the main tank, then to the other tanks by gravity, until the water reaches all the floors (Gupta & Thawari, 2016).

In addition to the use of the solar in heating the water for different uses should be considered, which is connected to solar panels, transferring the heat to the tank (United States Environmental Protection Agency, 2020).

Moreover, for the drainage systems and the treating of the black water should be disposed as well, while the grey water will be reused to irrigate the greenery within the Vertical buildings. The recycling of Grey Water needs separate network that after the sweat water supplied and distributed to the whole building, the wastewater will flow down by the high gravity load via special network pipe (figure 12) using a different technique. The greywater (no longer wastewater) will move from the upper levels, pouring fast as a bullet, so it requires slowing dawn via service floors in multi-stage

Figure 11. Multiple Pump System (Dummies, 2017, developed and drawn by Authors, 2020)


Figure 12. Grey Water Recycling (Authors, 2018)

4. Results According to Gulf Insider [28], has reported that in 2017

Bahrain had a shortage of housing units of 75,000. Also, during 2017, established according to the population statics and the standard accommodation of dwellings size are for 290,000 units and the available are 216,000 units. Nevertheless, when we consider the housing quality.

Architects and town planners cooperate to reach the suitable conditions for houses to accommodate the living of humans. Cultural characteristics and socioeconomic of the community are serious roles and issues. Those roles and issues are respected with their conditions when designing housing units. Moreover, vertical cities represent sustainability and affordability, fulfilling and acting towards the housing conditions, with an appropriate price, architects and planners find this a big challenge. Categorising the housing conditions into a variety of groups, yet the categorisation that can be considered to be appropriate containing three groups.

The environmental conditions, including noise and climate, belong to the first group. The noise and climate discusses humidity, heat and ventilation. Design aspects and housing materials, including construction, materials, building, finishing materials, density and privacy belongs to the second group. Moreover, the proper provision of services belongs to the third group. The proper provision checks and verifies satisfactory and suitable standards for the living, consisting of electricity, potable water, and appropriate sewage disposal system and garbage collection.

Moreover, building communities vertically, giving a solution for sustainable vision issues: the natural environment, the social and the engineering elements. Therefore, when considering the quality of the sustainable vertical housing projects, it should consider the following conditions a. Environmental housing conditions in term of noise,

thermal and Heat factors, as well as, humidity and condensation, ventilation in houses and in the spaces between, allowing the wind flow between spaces, and letting natural lighting and ventilation to all living provision of the spaces between the units to go through the vertical cites. Having greenery upon roofs

and facades will act significant progress towards controlling the reasons of Urban Heat Island (UHI).

b. Economically, consider modern technology for the provision of services for each unit in term of electricity, water supplies, Sewage disposal, and Solid waste management. Going vertically will reduce the load upon transportation and traffic, roads, and movability in City, which are significant problems in the city. Of course, it will need special treatment of vertical infrastructure and wastes treatment. Recycle and reuse the greywater will be a priority in dealing with this Vertical Dimensions issues. Structure system and emergency evacuation is still a point of discussion. Number of car parking in the city will be reduced, which will reduce the daily cost of travelling for the residences outside their vertical city.

c. Socially, housing design and the relation between Vertical cities’ components, construction system, Privacy & Density, Aspects of design, and Building materials. Moreover, the Communal spaces should set aside for recreational activities for the different age group. These Communal spaces in between and distribution of the uses and functions to create healthy and comfortable spaces between the Vertical cities components as well as having suitable social Interaction spaces. Moreover, access to houses can be achieved without the sacrifice of privacy to other adjoining. The properties of communal spaces should have a proper laying out of housing units, allowing for the reasonable distance between the units. This will allow the permitting of the preservation of privacy, provision of satisfactory through access, through maximum use of footpaths and managing to a great extent the possibility of privacy. Children will have spaces in safe of traffic problems this, consequently, would protect their lives, but it may create noise from the other hand. On the other hand, the designer should consider the phobia of the high rise building upon category of residences.

Therefore, Vertical Cities are a sustainable solution for accommodating a large number of inhabitants with less land area; for limiting the land reclamation upon the seawater cases, providing the needs of every citizen, reducing the expenses in reclaiming land and controlling the land scarcity.

From field survey and the analysing of different case studies, they mostly contain housing units, offices, commercial, service facilities and public parks. They are located near public transportation, as well as they have an impressive vertical circulation, which is fast. All of them are creating a community and a neighborhood, mostly by providing public gardens and spaces throughout the structures. All following the horizontal urban pattern with the open spaces. Moreover, parking is on the ground floor, or basement then comes to the offices or the facilities. Housing is located within the upper levels. In those


complexes, every specific storey has a garden or a public space or mixed facilities within the general context or an open court, from where an individual will start their adventure through the building. All of the cases are manipulating the spaces and the building, to provide the maximum natural lighting and ventilation. Having vertical cities requires the understanding of different aspects and issues towards the followings.

While talking about the selection Criteria for Site, The Vertical Cities criteria for selecting the location of the site illustrated in table 1, as well as programs and technical guidelines.

Environmental Criteria; corresponds to basic needs of air, noise and light quality, as well as, views. This factor should not be the most important one, as a vertical city by nature, defies all these features through its height. Air quality - away from hazards sources of smell or air quality. Beside the optimum exposure to sun and wind breeze, but also the assurance that the new building will not affect the wind and natural light quality in the area negatively. In addition, the quality of views from not only the building but also its effect on the surrounding area.

Urban Criteria; a vertical city is an independent entity, generally disconnected from its surroundings. However, there is a need to consider a healthy relationship between land and vertical development. From this perspective, in an ideal future, each vertical city would include the primary residential, working, service and commercial needs of citizens, while the surrounding area. In between, vertical cities would support the commercial, educational, health and primary functions of the country, such as hospitals and clinics, universities, schools and nurseries, research labs, etc. In addition, it should have ministries, banks, headquarters, shopping malls, public parks, etc. the accessibility that the building has to be located in a highly accessible place for private vehicles, public transportation and potential pedestrian routes; allocating public transportation hub (concentration of Bus, Metro, Train, Airport Buses, etc.)

A primary services support the proximity to main public support facilities such as government, services, educational, commercial (ministries, shopping malls, universities, headquarters and public parks). Besides, a

dense and consolidated urban area with a compact and consolidated metropolitan area.

Social Criteria; refers to the suppression of an emergent need such as housing, services, education and so on, basic commercial and facilities need, offices/services and housing need

Economic Criteria; that concern the land availability and Cost. The cost of land should be balanced with the overall construction price, which means that considering the verticality, the price of the property does not need to be very low, as there is maximum optimization. However, it cannot also be too expensive to make the project accessible to Bahrainis and low-income citizens. Moreover, the added Value of the location within an area that as a shortage of basic services and commerce will mean an immediate revenue for the project. In addition to the visibility; considering the building is supposed to change the way Bahrainis live; it should be able to act as a landmark and highly visible from surrounding areas.

Therefore, it is recommended to locate the site within a mixed-use area, as there are medical, commercial, residential, governmental and educational facilities.

Moreover, the assumption for inhabitants’ numbers within the vertical city program is very significant and should be studied carefully. An assumption of having a complex of 2500 inhabitants, one floor will contain six apartments, each for five inhabitants. Nine hundred employees are hired from the outside and an average of visitors per month of 2000 people. 1965 inhabitants who are occupying the building will visit the public facilities and services. However, there will be an estimation of 1500 visitors and employees within the services and facilities. So, 1965 inhabitants +1500 visitors = 3465 people. Also, 93 apartments occupied by 590 Low-income workers. Thirty-one bachelor flats and serviced apartments for visitors and temporary workers, as well as, small boutique hotel with a total of 32 flats. The total number of flats and apartments 463. The total number of temporary and permanent inhabitants 2851 inhabitants. There will be two towers, each tower is 17 floors residential, and each floor has nine apartments: 17 floors X nine apartments per floor = 153 apartments X two towers = 306 housing unit.

Table 1. Site Selection Criteria (Author, 2018)


Figure 13. Vertical Distribution Section (Authors, 2018)

Building Top View From Ground Till the Sixth Floor First Plaza (Every number of floors)

Figure 14. Horizontal Distribution (Authors, 2018)

Therefore, the accommodation of 2851 inhabitants (about 570 families) within the project that runs by the governmental sector is 306 units x 400m2 (area of the unit) = 122,400 m2 in the horizontal direction. This example shows the huge saving for the land in each project (figure 13 & 14)

5. Discussion

Warning the society that, “Land reclamation work had increased by 90 percent from 2002 to 2007” (El-Ghonaimy & Javed, 2018), therefore the solving of the Housing Dilemma will be via the” Vertical Dimensions”. It will help in solving the limitation of land as the sky has an infinite area. They will solve the housing problems, as will provide the need for individuals in a vertical sustainable environment. Those structures will stop the reclamation of land; congestion will be avoided in traffic and spaces. The Kingdom of Bahrain will have a better budget, as they saved and solved the treating of land, the housing issues and the architectural issues, resulting in an urban organization. The Bahrain strategic master plan 2030 considered this issue as a priority. The Vertical Cites are one of the key solutions to all of the above issues, saving the land and the marine. It will enhance the social aspects and offer a sustainable lifestyle, which is disappearing due to the negative planning of suburbs. The kingdom of

Bahrain is concerned regarding these issues. Vertical City is a multifunctional building. A vertical

village and a vertical city are planned and designed to offer all the necessary needs, facilities and services that a typical village or city possess. Achieving sustainable vertical cities and growing vertically is not an easy issue that when designing such projects. Vertical city affects and is affected by the guidelines of the Bahrain 2030 strategy for services, infrastructure, economic, social and environmental dimensions. The designers of such projects should integrate the principals of sustainability (social, economic and environmental) in their designs with the surrounding environment. The social characteristics of the users in general and the human comfort in particular, play a significant factor in succeeding such an idea. This social dimension could be achieved through an appropriate combining for the vertical city’ components in term of the units designs and building construction system, suitable building materials, finishing materials, designing the outdoor spaces and the landscape around the house with respect to the environmental housing conditions.

Vertical City contains residential, public, entertainment, educational spaces, as well as food production, social and governmental services. On the other hand, multifunctional buildings include residential hotels, shopping centres and office spaces. Vertical is a solution to sustainable living; it has the potential to create a sustainable life (King & Wong, 2015).


Concisely, vertical cities community will create a new definition of a neighbourhood in the urban community of Bahrain. However, it will be functional, open to the public, approachable and endurable. Vertical cities are a sustainable solution to enhance the developing of urbanism in Bahrain. Furthermore, land scarcity will be overcome, and the ecology will be saved by controlling the reclamation reasons upon the surrounding body water. Vertical communities will be able to accommodate a large number of inhabitants with less amount of land. Also, controlling many sources of pollution resulting from transportation. Technology will be used to operate and creating smart solutions in the building to control and manage energy consumption.

The construction of such projects will develop the construction technology and techniques in addition to enhancing the skilled labour market and provide job opportunities for the residence in terms of engineering elements and the interaction of the social and the economic activities and facilities. The creating of new activities, events, and special types of trading will there as well. Land use, mixed-use, pedestrians and friendly community designs will be enhanced. Designers will be focused on the human scale, providing spaces for pedestrians, shops, work, reducing the traffic and benefiting residents’ health. People will have a new alternative lifestyle, offering a variety of open spaces for housing units, shopping spaces, transportations. This will lead to the controlling of the sprawl; giving stability to the neighbourhoods, creating a neighbourhood identity; giving the sense of place and providing the blocks with an exclusive and unique character, enhancing the community conditions. However, in the developing countries, there are many issues, which are overloading the shoulder of the designers for such projects such as the arranging of the social services, the fire precaution, the technical solutions for the infrastructure, waste management, vertical circulation, the cost of the running maintenance, which are still a big challenge while thinking about vertical cities. Such a project in the hot-humid country will: a. Create places that meet social, environmental,

cultural, and aesthetic and practical requirements. b. Improve how people interact with their new vertical

city environment. c. Reduce the negative impacts that human use has upon

sensitive urban problems d. Adding to the general concept, as well as, preparing a

primary master plan, then the detailed designs will come next.

e. Residents will have the high value of the sharing spaces to influence the Qualitative Performance of the Voids easy accessibly for time, place, and Activities (figure 15)

Figure 15. Bound the social interaction within common spaces inside the vertical cities (Authors, 2018).

Acknowledgment I would like to state and express my sincere thanks to the

father of the first author Mr Bahaa Yusuf for his support and initiative idea for the research. Sincere thanks to Prof. Dr. Agr. Kai Tobias, Department of Spatial Environmental Planning, Technische Universitat Germany and to Ms Susana Saraiva for her sharing knowledge and support.


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Compressive Behaviour of Circular, Square, and Rectangular Concrete-Filled Steel Tube Stub Columns

Alireza Bahrami1,2,*, Ali Mahmoudi Kouhi2

1Department of Building Engineering, Energy Systems, and Sustainability Science, Faculty of Engineering and Sustainable Development, University of Gävle, 801 76 Gävle, Sweden

2Department of Civil Engineering, Abadan Branch, Islamic Azad University, Abadan, Iran

Received August 24, 2020; Revised October 22, 2020; Accepted October 30, 2020

Cite This Paper in the following Citation Styles (a): [1] Alireza Bahrami, Ali Mahmoudi Kouhi, "Compressive Behaviour of Circular, Square, and Rectangular Concrete-Filled Steel Tube Stub Columns," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1119-1126, 2020. DOI: 10.13189/cea.2020.080538.

(b): Alireza Bahrami, Ali Mahmoudi Kouhi (2020). Compressive Behaviour of Circular, Square, and Rectangular Concrete-Filled Steel Tube Stub Columns. Civil Engineering and Architecture, 8(5), 1119-1126. DOI: 10.13189/cea.2020.080538.


Abstract In this paper, the compressive behaviour of circular, square, and rectangular concrete-filled steel tube stub (CFSTS) columns is assessed. Nonlinear three -dimensional finite element models for simulating the behaviour of the columns are developed with the aid of the finite element analysis package ABAQUS. Modelling result is compared with the experimental test result to validate the modelling. It is found that the obtained load-axial strain curves of the columns from the finite element analysis and experimental test are notably close to each other and the modelling is finally validated. Then, the analyses of the developed models of the columns are done in accordance with the validated method. Various parameters are adopted in the analyses including the load eccentricity, cross-sectional shape, and steel tube thickness. It is concluded that as the load eccentricity of the columns is increased, their ultimate load-carrying capacity, energy absorption capacity, and stiffness are decreased. Also, the circular columns have generally better performance than their rectangular and square counterparts. The hierarchy of the cross-sectional shapes of the columns from the ultimate load-carrying capacity and energy absorption capacity viewpoints is the circular, rectangular, and square shapes. Although the initial stiffness and slope of the stiffness curves of the rectangular and square columns are slightly higher than those of the circular columns, their stiffness distribution is non-uniform. Furthermore, thicker steel tube leads to greater ultimate load-carrying capacity, energy absorption capacity, and stiffness. Failure modes of the

columns are achieved and discussed as well.

Keywords Concrete, Steel, Tube, Stub Column, Energy Absorption Capacity, Stiffness, Load-Carrying Capacity

1. IntroductionConcrete-filled steel tube (CFST) columns are made up

of steel tube and concrete infill. In the fabrication of the CFST columns, concrete is poured in layers inside the steel tube and vibrated by a vibrator. The advantages of large ductility of steel and high stiffness of concrete have appropriately been combined by the CFST columns. The CFST columns have increasingly been used in civil engineering structures throughout the world. Economies of reinforced concrete columns and the speed of construction and the constructability of steel columns have been provided by the CFST columns. These accomplished advantageous points by the CFST columns have resulted in significant economic saving in the overall structures of projects.

Several research works can be found in the literature on the CFST columns. The use of high strength concrete in steel box columns was examined by Uy and Patil [1]. Liu et al. [2] performed tests of high strength rectangular concrete-filled steel hollow section stub columns with

1120 Compressive Behaviour of Circular, Square, and Rectangular Concrete-Filled Steel Tube Stub Columns

different aspect ratios subjected to axial loading. Self-consolidating concrete-filled hollow structural steel stub columns were tested by Han et al. [3]. Tao et al. [4] conducted tests of concrete-filled stiffened thin-walled steel tubular columns. Han et al. [5] evaluated concrete-filled steel tubular stub columns subjected to axially local compression. Liew and Xiong [6] reported the effect of preload on the axial capacity of concrete-filled composite columns. Passive confinement effect of the steel tube in concrete-filled steel tubular columns was studied by Oliveira et al. [7]. Performance of concrete-filled stainless steel tubular columns was assessed by Uy et al. [8] under axial compression and combined action of axial force and bending moment. Bahrami et al. [9-11] investigated and developed unstiffened and stiffened concrete-filled steel composite stub columns. An experimental study of concrete-filled round-ended steel tubular stub columns was done by Faxing et al. [12] under axial compression. Zhu et al. [13] did experimental and numerical studies of large diameter concrete-filled high strength steel tubular stub columns subjected to axial compression. Behaviour of concrete-filled cold-formed steel tubular stub columns with thicker tubes was experimentally examined by Zhu et al. [14]. Li et al. [15] described mechanical behaviour of eccentrically loaded high strength concrete-filled high strength square steel tube stub columns. Jin et al. [16] presented a three-dimensional meso-scale numerical model that could consider the heterogeneities of concrete and concrete-steel tube interactions in order to evaluate the size effect in concrete-filled steel tubular columns. Dai et al. [17] assessed strength of concrete-filled stainless steel tube stub columns through experimental and numerical programs. Nevertheless, the compressive behaviour of concrete-filled steel tube stub (CFSTS) columns with different cross-sectional shapes of circular, square, and rectangular is studied in this paper.

The current paper is concerned with the compressive behaviour of circular, square, and rectangular CFSTS columns. As the accuracy of the finite element modelling is established using ABAQUS, the method is followed for the developed CFSTS columns. Load eccentricity, cross-sectional shape, and steel tube thickness are considered as the parameters in the analyses of the columns. Effects of these parameters on the ultimate load-carrying capacity, energy absorption capacity, and stiffness of the columns are discussed. Failure modes of the columns are evaluated too.

2. Materials and Methods Materials employed in the studied CFSTS columns

consist of the perimeter steel tube filled with concrete. This section deals with the experimental test and numerical modelling of the CFSTS columns. An

experimental test done on a CFSTS column [18] was modelled by ABAQUS in order to validate the nonlinear three-dimensional finite element modelling of the CFSTS columns in this research.

2.1. Experimental Test of CFSTS Column

The CFSTS column was tested under concentric load applied on its entire section. The main geometric characteristics of the tested column were diameter (D), thickness of steel tube (t), and length/diameter ratio (L/D) respectively as 114.3 mm, 3.35 mm, and 3. The concrete compressive strength was 32.7 MPa while the yield stress of the steel tube was 287.33 MPa. The test was conducted utilising an Instron 8506 servo hydraulic actuator with electronic displacement control.

2.2. Numerical Modelling and Nonlinear Analysis of CFSTS Column

The tested CFSTS column was modelled using ABAQUS as a popular finite element software. ABAQUS has a wide range of applications in solving physical problems and phenomena such as solid mechanics, fire and heat transfer, mass infiltration, thermal analysis of electrical components, acoustics, soil mechanics, and piezoelectrics. It can investigate and analyse results very close to reality by carefully examining them.

2.2.1. Validation of Modelling The method of the modelling validation was such that

the experimentally tested column was completely modelled so that the modelling result could be accomplished very close to the test result, accordingly, the modelling was validated.

All the considered features in the tested CFSTS column were also adopted in the modelling. Modelling the steel and concrete materials of the columns was performed as its fundamental part [19]. A concrete damage plasticity model was employed in modelling the concrete material [20]. Since concrete was greatly influenced by the confinement effect of the steel tube, its behaviour was different from other common models. The ratio of the second stress invariants on the tensile and compressive meridians (Kc) was selected as 0.667 [21, 22]. The viscosity parameter utilised for better convergence was 0.0001. A bilinear steel material model which had progressive hardening behaviour and softening effects was employed for modelling the steel material [23, 24]. The Poisson’s ratios of the steel tube and concrete were also taken as 0.3 and 0.2, respectively.

The concrete infill and steel tube were respectively modelled by the use of the solid element C3D8R and the shell element S4R. The constraint called Embedded Region was utilised to model the contact surface between the concrete core and perimeter steel tube. The used friction coefficient (μ) for the contact was 0.3 [21, 22]. The load


was applied by the displacement method. The optimised mesh size of 15 mm was taken into account for the column which was obtained from a conducted convergence study on the mesh size of the model. This mesh size showed to be able to conclude accurate results. Modelled CFSTS column is presented in Figure 1.

The modelled CFSTS column was nonlinearly analysed and the load-axial strain curve was plotted from the analysis result. The finite element analysis result was compared with the experimental test result, as illustrated in Figure 2. It is noteworthy that as the differences between the resulted values and behaviours of the test and software model were lower in the validation process of the modelling, the analyses results of the developed models would be more accurate and reliable. Hence, it is observed from the figure that the curves agreed very well with each other with respect to their ultimate loads and behaviours. This good agreement obviously revealed the accuracy of the modelling and the modelling method was validated. Accordingly, the proposed modelling method could lead to exact results which was adopted for modelling the developed CFSTS columns.

Figure 1. Modelled CFSTS column

Figure 2. Comparison of finite element analysis result with experimental test result of CFSTS column

2.2.2. Development of CFSTS Models With regard to the accomplished validated modelling

method of the column, the CFSTS columns with the same height and materials characteristics were developed accounting for different parameters as load eccentricities (25 mm and 50 mm), other cross-sectional shapes (square and rectangular), and other steel tube thicknesses (2 mm and 5 mm). The columns were analysed and their results were then achieved. In the columns labels of section 3, the first two letters respectively represent the cross-sectional shape and column as CC (Circular Column), SC (Square Column), and RC (Rectangular Column). In addition, the numbers following e (eccentricity) and t (thickness) respectively refer to the values of the load eccentricity and steel tube thickness in mm.

3. Results and Discussions The obtained results from the analyses of the developed

CFSTS columns are presented herein. Also, effects of the considered parameters as load eccentricity, cross-sectional shape, and steel tube thickness on the ultimate load-carrying capacity, energy absorption capacity, and stiffness of the columns are discussed.

3.1. Effects of Load Eccentricity on Ultimate Load-Carrying Capacity, Energy Absorption Capacity, and Stiffness of CFSTS Columns

The analysed CFSTS column under the concentric load was also analysed under eccentric loads. Different eccentricities of 25 mm and 50 mm were applied for the load. Figure 3 demonstrates a typical modelled CFSTS column showing the load eccentricity and support conditions.

The load-axial strain curves were achieved for the columns (Figure 4). According to the figure, the ultimate load-carrying capacity of the CFSTS column with the load eccentricity of 0 mm (CC-e0-t3.35) was 729 kN which was decreased to 630 kN and 495 kN respectively by increasing the eccentricity to 25 mm in CC-e25-t3.35 and 50 mm in CC-e50-t3.35. This issue indicates that increasing the load eccentricity from 0 mm to 50 mm reduced the ultimate load-carrying capacity of the column for 32.1%. Because the eccentricity of the load brought the secondary moment with itself which had a negative effect on the capacity of the columns and reduced their ultimate load-carrying capacity.

The energy absorption capacities of the columns are compared in Figure 5. As the load eccentricity was increased from 0 mm to 25 mm and 50 mm, the energy absorption capacity was decreased from 7483 kN.mm to 7017 kN.mm and 5334 kN.mm, respectively. Because with increasing the load eccentricity, stress concentration occurred on small parts of the steel tube which caused it to


fail sooner and it prevented the application of the full capacity of the steel tube to absorb the energy. On the other hand, the concrete core inside the steel tube also suffered from internal shear cracks and partial failure due to the eccentric loads. Over time, these cracks were developed and caused more stress on the steel tube which finally led to lower energy absorption capacity of the columns.

The columns with larger load eccentricities resulted in lower stiffness (Figure 6). The initial stiffness of the column was reduced for 41.1% as the load eccentricity was enhanced from 0 mm in CC-e0-t3.35 to 50 mm in CC-e50-t3.35. In the column with 0 mm eccentricity, all or a large part of the capacity of the column was successfully utilised for the stiffness, but in the columns with larger eccentricities, smaller part of the capacity of the column was employed because of the existence of non-uniform stresses in the concrete core and steel tube which created and developed cracks in the cross-section.

Figure 3. Typical modelled CFSTS column showing load eccentricity and support conditions

Figure 4. Effect of load eccentricity on ultimate load-carrying capacity of CFSTS columns

3.1.1. Failure Modes of Circular CFSTS Columns with Different Load Eccentricities

Failure modes of the circular CFSTS columns are illustrated in Figure 7. As it can be seen from the figure, less buckling occurred in the column with 0 mm load eccentricity (e = 0 mm) than in the columns with the eccentricities of 25 mm and 50 mm. Also, the failure and stress distribution were in a more uniform way along the entire length of the column with e = 0 mm. However, buckling occurred about the top of the columns with the load eccentricities of 25 mm and 50 mm which revealed the concentration of stresses about the top of these columns.

Figure 5. Effect of load eccentricity on energy absorption capacity of CFSTS columns

Figure 6. Effect of load eccentricity on stiffness of CFSTS columns

(a)

Figure 7. Failure modes of CFSTS columns: (a) CC-e0-t3.35, (b) CC-e25-t3.35, (c) CC-e50-t3.35


(b)

(c)

Figure 7. Continued

3.2. Effects of Cross-Sectional Shape on Ultimate Load-Carrying Capacity, Energy Absorption Capacity, and Stiffness of CFSTS Columns

In addition to the circular cross-sectional shape for the column, other shapes of the square and rectangular were considered for the columns. These columns were modelled and analysed. All the specifications of the circular column were taken into account for the square and rectangular columns. Also, the same cross-sectional area and length of the circular column were adopted here so that the concrete volume and steel tube area were identical for all the columns.

As it is demonstrated in Figure 8, the circular column had higher ultimate load-carrying capacity than the rectangular and square columns which were respectively as

729 kN, 677 kN, and 670 kN. It was uncovered that when the cross-sectional shape changed from square to circular, the ultimate load-carrying capacity of the column was improved for 8.8%. However, the ultimate load-carrying capacities of the square and rectangular columns had a slight difference. Thus, the hierarchy of different cross-sectional shapes of the columns with respect to the ultimate load-carrying capacity was the circular, rectangular, and square shapes. The rigidity of the plane portions of the steel tube in the rectangular and square sections was not sufficient to withstand the internal pressures owing to the expansion of the concrete core. Therefore, only concrete in the centre and corners of the cross-section was effectively confined, however, the confinement effect of the steel tube in the circular column was identical throughout the perimeter of the tube. This point finally resulted in the failure of the rectangular and square columns in lower ultimate loads than that of the circular column.

Figure 8. Effect of cross-sectional shape on ultimate load-carrying capacity of CFSTS columns

It is clear that the slope of the graphs in Figure 9 as well as their behaviour were almost similar for the energy absorption capacity of the columns, but the maximum force absorbed by the circular column was 17.3% and 12.2% higher than those of the square and rectangular columns, respectively. Because the distribution of tri-axial and loop stresses created by the steel tube was carried out more appropriately and uniformly in the circular column than the square and rectangular columns due to not having plane portions and angles. Also, the friction between the concrete core and steel tube in the circular cross-section was more which caused the delay of the steel tube failure and its proper energy absorption. The same hierarchy of the cross-sectional shapes of the columns from the ultimate load-carrying capacity view was also witnessed from the energy absorption capacity viewpoint as the circular, rectangular, and square shapes.

The values of the initial stiffness of the circular, square, and rectangular columns were respectively as 1477 kN/mm, 1530 kN/mm, and 1583 kN/mm (Figure 10). According to the obtained results, it is obvious that the initial stiffness of the rectangular column was higher than the other two


columns, however, the overall stiffness of the rectangular and square columns was not properly distributed throughout their sections based on the behavioural form of their curves. Owing to more uniform distribution of the stiffness in the whole section of the circular column than the rectangular and square columns, the circular section was preferred to others.

Figure 9. Effect of cross-sectional shape on energy absorption capacity of CFSTS columns

Figure 10. Effect of cross-sectional shape on stiffness of CFSTS columns

3.2.1. Failure Modes of CFSTS Columns with Different Cross-Sectional Shapes

Aside from the failure modes of the circular columns which were displayed and discussed in section 3.1.1, Figure 11 indicates the failure modes of the square and rectangular columns. It can be perceived from the figure that the failure modes of the columns were characterised by their buckling. High tensile stresses occurred on one side of the columns and compressive stresses on the other side.

3.3. Effects of Thickness of Steel Tube on Ultimate Load-Carrying Capacity, Energy Absorption Capacity, and Stiffness of CFSTS Columns

Since the confinement effect of the steel tube on the concrete core is an important influencing factor on the performance of the CFSTS columns, effects of the steel tube thickness are assessed here. The increase of the steel

tube thickness from 2 mm to 5 mm resulted in the improvement of the ultimate load-carrying capacity of the columns for 46.4% (Figure 12). Because thicker steel tube, lower diameter to thickness ratio (D/t), made the steel tube have better confinement effect on the concrete core and delayed the failure of the columns that finally led to their larger ultimate load-carrying capacity.

(a)

(b)

Figure 11. Failure modes of CFSTS columns: (a) SC-e0-t3.35, (b) RC-e0-t3.35

The energy absorption capacity of CC-e0-t2 was 5975 kN.mm which was enhanced to 9224 kN.mm (CC-e0-t5) by the increase of the steel tube thickness from 2 mm to 5 mm, an enhancement of 54.4% (Figure 13). Since the main role in the energy absorption of the CFSTS columns is played by the steel tube, increasing the steel tube thickness improved its mentioned role and increased the energy absorption capacity of the columns.

The enhancement of the steel tube thickness enhanced the stiffness of the columns (Figure 14) which once more was owing to its positive effect on increasing the confinement of the steel tube on the concrete infill that


helped prevent the occurrence of cracks in concrete and early local buckling of the columns.

Figure 12. Effect of steel tube thickness on ultimate load-carrying capacity of CFSTS columns

Figure 13. Effect of steel tube thickness on energy absorption capacity of CFSTS columns

Figure 14. Effect of steel tube thickness on stiffness of CFSTS columns

4. Conclusions This paper focused on the compressive behaviour of

circular, square, and rectangular CFSTS columns. The columns were analysed using ABAQUS. Modelling verification of the columns was established by comparison of the modelling and test results. Developed columns were analysed considering the parameters of load eccentricity, cross-sectional shape, and steel tube thickness. Effects of these parameters on the ultimate load-carrying capacity,

energy absorption capacity, and stiffness of the columns were investigated. As a conclusion, the ultimate load-carrying capacity, energy absorption capacity, and stiffness were reduced by increasing the load eccentricity. With regard to the ultimate load-carrying capacity and energy absorption capacity, the hierarchy of the cross-sectional shapes of the columns was the circular, rectangular, and square shapes. Generally, the circular columns were superior to the rectangular and square columns. Larger ultimate load-carrying capacity, energy absorption capacity, and stiffness were achieved by enhancing the steel tube thickness. Buckling and large stress concentration were mainly observed in the failure modes of the columns. Future scope of this research is the evaluation of concrete-filled steel tube slender columns considering various variables influencing their structural behaviour.

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Sustainable Hospital Architecture - Potential of Underground Spaces

Irina Bulakh1,*, Iryna Merylova2

1Department of Design Architectural Environment, Kyiv National University of Construction and Architecture, Kyiv, Ukraine 2Department of Architectural and Urban Planning, State Higher Education Establishment “Pridneprovsk State Academy of Civil

Engineering and Architecture”, Dnipro, Ukraine

Received September 10, 2020; Revised October 19, 2020; Accepted October 25, 2020

Cite This Paper in the following Citation Styles (a): [1] Irina Bulakh, Iryna Merylova , "Sustainable Hospital Architecture - Potential of Underground Spaces," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1127 - 1135, 2020. DOI: 10.13189/cea.2020.080539.

(b): Irina Bulakh, Iryna Merylova (2020). Sustainable Hospital Architecture - Potential of Underground Spaces. Civil Engineering and Architecture, 8(5), 1127 - 1135. DOI: 10.13189/cea.2020.080539.


Abstract The article is a part of the study devoted to the urban planning of healthcare system spatial development, hospitals in particular. The research is based on systemic and integrated analysis. A number of case studies are provided. The article addresses topical issues of possible ways to improve environmental friendliness, energy efficiency and harmonization with the natural and artificial environment of health care facilities, which will contribute together to a sustainable vector of architectural development. One of the newest and most promising ways of architectural development of medical institutions is associated with the active integration of the potential use of underground space into the design of hospitals. The article considers the best experience of designing hospital buildings in which the underground space performs various functions, as well as a number of practical techniques aimed at balancing the uncomfortable feeling of "underground" of the premises located in the basement. The following progressive directions of using underground spaces in the design of modern hospitals have been identified, described and analyzed: underground location of rooms for patients, staff and technical purposes. The proposed approach allows: reduction of the perimeter of a building, which interacts with changing climatic conditions; natural stable temperature; potential use of different types of heat pumps as a "green" means of increasing heat energy (soil, ambient air and groundwater); noise reduction from the environment; using the area of the entire land plot with a significant underground extension.

Keywords Architecture and Urban Planning,

Underground Space, Hospital Design, Atrium, Courtyard, Hospital Energy Efficiency

1. IntroductionThe events of the last six months have forced the entire

civilized world to pay attention to the quality and efficiency of healthcare. In all countries medical sector experienced quite significant difficulties – there was a lack of equipment and places in hospitals, many countries were forced to deploy temporary hospitals for the daily admission of a large number of patients who had no chance of recovery in outpatient treatment. This "shock therapy" and a harsh natural reminder of the value and vulnerability of human life and health, we hope in the near future, will lead to international and national programs for the development, expansion and modernization of healthcare and one of its key elements – hospitals, in particular.

Modern hospitals are complex multidisciplinary medical facilities that require a lot of space to accommodate various components of the units. This can be achieved in several ways such as the design of multi-storey buildings, medium-rise buildings in large urban areas, etc. Each of these areas has positive and negative features and is selected in accordance with the specific urban context and opportunities. In case of construction of a new hospital or a current medical building extension in the existing urban environment, a solution to build a multi-storey hospital is

1128 Sustainable Hospital Architecture - Potential of Underground Spaces

often chosen. However, there may be a number of limitations and

conflicts within the urban context: required height for sufficient hospital space and the height of historic buildings; design and construction restrictions as for the height of buildings according to the state regulations in some countries; complicating the formation of artistic and aesthetic image of a hospital, which would create a psychological feeling of peace and confidence in patients.

Taking into account these aspects, construction of a new hospital in a large urban area can take place only on the outskirts of the settlement or outside it. This article, as an alternative and innovative way of architectural design of hospitals, which avoids the problems and issues of preventing high-rise or free and expansive construction of a hospital building in large urban areas, proposes an approach related to partial integration of medical buildings into underground space. In addition to the already mentioned positive features, it is important that this project approach also deals with the potential of underground space in terms of sustainable development of architecture and healthcare sector, in particular.

The research questions in this article are as follows: аn ecological and sustainable development approach to the architecture of medical buildings, the aspect of human perception of the underground space, sustainable development of the architecture of healthcare facilities by the example of the latest experience of leading countries in the medical field. Thus, space, sustainability and therapeutic effects are the main issues.

2. Literature Review Research of underground space and the peculiarities of

its use in the design of hospitals was partially carried out in the book Urban Underground Space Designing China: Vernacular and Modern Practice [1]. This study was the first to be presented in English to outline and illustrate China's experience in designing and using underground non-residential public facilities, including the architecture of hotels, hospitals, theaters and shopping malls. The main emphasis in the study is to put on the location of technical and auxiliary hospital facilities on one underground floor. It is necessary to mention that over the period of 30 years, after this book was published, a lot has changed - new building materials have appeared, building technologies have improved [2], [3]. Nowadays, the issues of high operating costs and the lack of free land resources are significantly relevant. Thus, this book in the article is considered from the point of view of the first publication, because it touched on the topic of underground space of hospitals but, of course, does not provide answers to all questions.

The investigations concerning traditional and historical experience of construction of underground city structures

in architecture on the basis of sustainable development of urban environment are also analyzed [4]. It was important to refer to national and historic experience of Iran, where underground spaced was traditionally created in urban environment. Returning to the architectural heritage of the past is also quite appropriate in the XXI century in connection with a new vector of civilized society development, which is based on environmental principles of sustainable development, energy savings and effective ways to reduce energy consumption in urban areas. An ecological and sustainable development approach to architecture of medical buildings is one of the key issues in this study, which describes historical experience and modern advances. Problems of the sustainable development of urban environment today are widely considered in many countries. Numerous symposia and conferences are held in this direction.

Also, the article is based on the research of I. Merylova and K. Sokolova in the field of cognitive approach to urban studies “A human in the urban space of the globalized world” (2020). The aspect of human perception of the underground space and psychological feeling of a human in it were considered. This topic is also one of the issues of the presented study about the architecture of medical buildings. The results obtained are briefly described in this article. This article uses the findings of the study devoted to the influence of architecture on a psychological state of a human, which are partially described in scientific articles and conference papers [5], [6].

The papers of the participants of The International Conference on Sustainable Futures: Environmental, Technological, Social, and Economic Matters (held at Kryvyi Rih National University, Kryvyi Rih, Ukraine, on May 20-22, 2020) were analyzed in the current article. At the conference, scientists from various scientific fields raised a number of issues with regard to geotechnical and geoenvironmental engineering, sustainable mining, sustainable construction and architecture, sustainable cities and society, sustainable materials and technologies, sustainable transport, sustainable energy, measuring, sustainability forecasting and monitoring [7]. It is noteworthy that the conference also addressed the issues of sustainable development of the architecture of healthcare facilities by the example of the latest experience of leading countries in the medical field [8]. The problems of sustainable and ecological approaches to architectural design of hospitals are raised in the research [8]. The best international experience of designing and operating hospitals based on the principles of sustainable development is considered. Examples and implementation experience of energy efficient technologies in healthcare institutions are analyzed and illustrated: natural ventilation, solar panels, rainwater collection, filtration and reuse of wastewater, providing green spaces on the roof and walls, sun protection, aerodynamic volumetric and spatial form. Studying and using the proven experience of the best


examples of ecological hospital buildings, recognized and certified at the highest levels of the world institutions for the development of sustainable future, will allow Ukraine to create the conditions for solving the crisis both in the sphere of healthcare and in the ecologically preserved environment of the country.

This article is a part of a comprehensive study of urban planning foundations of territorial and spatial development of the system of children's medical complexes, which is conducted within the doctoral research in the field of architecture and urban planning. The article is an ecological and natural continuation of a number of scientific works [9], [10], [11] on the way to find the latest theoretical and practical tools, methods and techniques in order to improve the quality and efficiency of architectural and urban planning solutions in architectural and urban planning design of various healthcare facilities. The article gives an overview of the existing literature on the research topic, and also offers case studies provided by the authors of the article.

3. Global Experience in the Design and Use of Underground Hospital Environment

Traditionally, in many countries around the world, when designing hospitals, the underground space was used as one floor and provided as a technical basement. This project approach was caused due to the need to quantify and expand the urban network of healthcare facilities, as well as due to a number of the following factors: focus on design and construction of typical projects in order to save time and money; use of economic construction and industrial methods and approaches; lack of understanding about energy crisis consequences and, as a result, failure to follow energy savings, search and integration of energy efficient technologies and solutions. In the post-Soviet countries, in particular in Ukraine, the underground (basement) spaces of healthcare facilities are in terrible condition, although they serve as technical premises (Fig.1, Fig.2).

Figure 1. Kyiv City Clinical Hospital №4, Kyiv, Ukraine

Figure 2. Clinical Hospital for Children, Perm, Russia

In most Ukrainian hospitals in basement there are dressing rooms for visitors, patients, staff, interns, as well as cafes, archival depositories, medical certificates collection points. With the lack of sanitary and hygienic standards support and aesthetic condition of the underground floor the use of these premises in their functions causes quite unpleasant feelings.

Figure 3. General view Bundang Seoul National University Hospital, South Korea

Figure 4. Natural setting Bundang Seoul National University Hospital, South Korea

Along with the outlined negative, inexpedient and


inappropriate experience of underground hospital space application, there is another approach that corresponds to the rational and environmental aspects of sustainable development of architecture of medical institutions. A similar modern example is the project of Bundang Seoul National University Hospital by JUNGLIM Architecture. Established in 2003, Bundang Seoul National University Hospital is located in a metropolitan area with a good natural environment adjacent to Bulgok Mountain and Tancheon (Fig. 3, Fig. 4). This picturesque natural environment caused some difficulties in 2009, when it was decided to expand the area of the hospital.

Changes in topography of the area for a new hospital construction made the architects look for compromises that would allow building a new hospital of the required size but still adjacent to the existing building and with natural insolation of stationary wards [12]. Among many search options, the architects managed to find a solution that allowed to harmoniously connect a new building with natural context, as well as with the existing hospital building. To achieve this result, a new 15-storey hospital building was developed underground – taking into account natural terrain, the architects placed from three to six floors underground (Fig. 5, Fig.6) [12].

Figure 5. Sectional drawing Bundang Seoul National University Hospital, South Korea

Figure 6. Cross-sectional drawing Bundang Seoul National University Hospital, South Korea

Most of the underground rooms were provided with natural light due to a number of techniques - anti-aircraft lights, linear two- and three-storey atriums, glass partitions, etc. As a result, the architects managed to eliminate the uncomfortable feeling of "undergroundness", which is usually caused in a room without natural light and visual contact with the environment.

The use of underground space in the construction of a hospital due to the hilly terrain can also be found in the project of The Sieff Hospital, designed by Weinstein Vaadia Architects in 2016 in Israel. The area for the design of the hospital, in addition to its topography, was also quite compact. Consequently, a significant part of the hospital building was integrated into the terrain, obtaining a practical underground location. To maximize the lighting of doctors' offices and other office space planned by the architects in the hospital's underground area, the project provides an open enclosed courtyard, which also opens up additional views of the landscape architecture in miniature (Fig. 7) [13].

Figure 7. General layout and cross section of The Sieff Hospital, Israel

The next visualization of rational underground space is Pars Hospital, a project implemented by New Wave Architecture company in 2016 in Iran. In this example, there is only one underground floor for technical use (parking for service vehicles, staff and patients), but it allowed them to ‘relieve’ the street and hospital territory from parking cars, which is very important for healthcare facilities in a dense urban environment (Fig. 8) [14]. Thus, Pars Hospital showed one of possible ways how to use underground hospital space for parking.


Figure 8. General layout and cross section of Pars Hospital, Iran

The project of New Hospital Tower Rush University Medical Center, designed by Perkins + Will company and built in Chicago, United States in 2012 is of some interest in this research. The project is attractive not only by a single underground floor for technical purposes, but also by its design technique – a number of small inclusive atriums (Fig. 9) [15]. The whole architectural idea made possible to solve certain tasks: to provide middle of the building with natural lighting, to create interesting public space with landscape "integration" of nature, to give this medical facility some individual features and aesthetics. Such approach could be suggested in the design of an underground medical environment – integrated "perforation" of some underground levels, which can be exposed to natural light and comfortable atmosphere.


Figure 9. "Nature capsules" in New Hospital Tower Rush University Medical Center Chicago, United States

Figure 10. Rey Juan Carlos Hospital, Madrid, Spain

Rey Juan Carlos Hospital project, by Rafaelde La-Hozу 2012, Madrid, Spain is one more to consider. The concept of this hospital project provided for the interaction of three main components: efficiency of process organization, light and silence. The architect also tried to combine the best achievements of hospital and residential architecture to obtain a new synthetic model of medical space. A special role in this model is given to the architecture of medical environment, where natural light and silence cause a therapeutic effect – "the use of architecture as a medical treatment". One of the main points in a building is sustainability - considering conditions of solar orientation, topography, building and green environment around in terms of urban conditions, as well as incorporated green materials and renewable energy technology to save resources and operating costs (for instance, green roof, natural light and ventilation inside the building). This general comment is of direct relevance to the purpose of this article - to show an integrated approach to sustainable hospital architecture, the component of which is to use the potential of underground spaces. The hospital also has an underground floor, but the whole building is built as if it is concealed from the environment - this technique and the effect of artificial illusion of "immersion" of the ground-based building in the underground space is associated with an attempt to create a special atmosphere with dimmed and controlled lighting and minimization of external and internal noise (Fig. 10) [16].

In terms of exploring the potential use of underground spaces in the design and construction of health facilities, the design experience of the Hospital of Sant Joan Despi Doctor Moises Broggi, jointly developed in 2010 by Pinearq + Brullet-De Luna Arquitectes team in Sant Joan Despí, Spain, is extremely valuable. Its non-standard and individual solution is based on elongated proportions of the construction site, as well as the architect's efforts to clearly distinguish all functions and human flows (visitors, inpatients and outpatients, medical center, emergency medical service, staff, etc.). All the main functions, according to the architects, should be autonomous, leaving the possibility for a clear orientation of visitors and


patients due to the constant relationship between external environment and interior of the building. It was decided to place care and outpatient care areas on the 1 underground floor to avoid the presence of wards and rooms for patients on the entrance floor (Fig. 11) [17]. An independent entrance for outpatient services allowed access for external visitors from two different entrances. Thus, Hospital of Sant Joan Despi Doctor Moises Broggi is an example of a hospital building where the underground floor is entirely used as a treatment space rather than an auxiliary and technical area.

Figure 11. Hospital of Sant Joan Despi Doctor Moises Broggi, Sant Joan Despí, Spain

The potential use of underground space is also very clearly revealed in the Ulm Surgical Center project carried out by KSP Jürgen Engel Architekten in Ulm, Germany. Most of the hospital building is integrated into the

landscape, thus actively using the underground space for medical purposes (operating rooms, intensive care units, clinics). The ground level part of the building is a 160-meter building that is extended horizontally above the ground and contains 235 beds in its treatment section (Fig. 12) [18]. To provide underground spaces with daylight, as well as to create a more natural and comfortable atmosphere of terrestrial spaces, the architects envisioned large courtyards in the project. Thus, the premises located on the underground level look and are perceived as a completely terrestrial environment.

Figure 12. Ulm Surgical Center, Ulm, Germany

4. Conclusions The architecture of healthcare institutions has changed

significantly over the last decade and continues to improve. In most developed countries, architects gradually refuse from traditional approach to architectural design and construction of medical institutions. The conventional approach in most countries is to design hospitals solely as "above ground" buildings. This article shows that today architectural practice is being developed, architects


explore new solutions (e.g. regarding natural light for underground space), and in some countries there are some hospital projects that are more innovative than others. And already today there is a rich experience of unique projects of hospitals, which are designed on the basis of sustainable development and ecological principles of design taking into account regional contexts and environmental potential. In this aspect, the direction of active use of positive opportunities for underground space integration in the design of healthcare facilities remains quite new and still uncommon. The location of various hospital functions on underground levels has many advantages: reduction of the perimeter of a building, which interacts with changing climatic conditions (which is especially important in countries with temperature fluctuations during the year); natural stable temperature in the room; facilitating the use of the potential of different types of heat pumps as a "green" means of increasing heat energy from alternative sources: soil, ambient air and groundwater; reduction of noise from the environment; possibility of using the area of the entire land plot with a significant underground extension, еtс [19], [20], [21].

Of course, extensive use of underground space also has a number of limitations and disadvantages. In particular, there is a problem with high groundwater level in the area for the construction of healthcare facilities. But most of the other shortcomings, such as a lack of daylight in underground rooms, can be solved in quite interesting alternative ways (with the help of various types of atriums, "light wells", means that reflect sunlight, or a courtyard, etc.).

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Recycled Aggregate Concrete Made with Silica Fume: Experimental Investigation

Ayser J. Ismail1, Khaleel H. Younis2,3,*, Shelan M. Maruf2

1Department of Building Construction, Erbil Technology College-Erbil Polytechnic University, Erbil, Iraq 2Department of Road Construction, Erbil Technology College-Erbil Polytechnic University, Erbil, Iraq

3Department of Civil Engineering, Tishk International University, Erbil, Iraq

Received July 26, 2020; Revised October 18, 2020; Accepted October 24, 2020

Cite This Paper in the following Citation Styles (a): [1] Ayser J. Ismail, Khaleel H. Younis, Shelan M. Maruf , "Recycled Aggregate Concrete Made with Silica Fume: Experimental Investigation," Civil Engineering and Architecture, Vol. 8, No. 5, pp. 1136-1143, 2020. DOI: 10.13189/cea.2020.080540.

(b): Ayser J. Ismail, Khaleel H. Younis, Shelan M. Maruf (2020). Recycled Aggregate Concrete Made with Silica Fume: Experimental Investigation. Civil Engineering and Architecture, 8(5), 1136-1143. DOI: 10.13189/cea.2020.080540.


Abstract This research deals with the behavior of recycled aggregate concrete (RAC). In this study an experimental work was undertaken. The study examines the effect of using recycled coarse aggregate (RCA) on the workability and the mechanical performance of RAC. The influences of using silica fume (SF) as cement replacement material on the performance of RAC were also examined. Silica fume was used at four contents (5%, 10%, 15% and 20%). The total number of mixes was six. Four mixes of RAC made with these four contents of SF, one RAC mix was made without SF and one mix was made with natural coarse aggregate (NCA) as a reference mix. The outcomes of this study reveal that workability and mechanical performance of RAC are lower than that made with NCA. Also, Silica fume has an adverse influence on workability of the RAC. However, the silica fume possesses a positive influence on mechanical properties of RAC. Silica fume can be used at contents of (10-20)% of cement mass to obtain mechanical performance for the RAC comparable to the concrete includes NCA.

Keywords Recycled Coarse Aggregate, Compressive Strength, Flexural Strength, Silica Fume

1. IntroductionConcrete is a constructional material which has been

utilized in construction industry for more than one century

[1]. This is due to its versatility, ease of shaping and low cost. However, concrete has been accused for the high amount of emitted CO2 during the process of its production including cement manufacturing, aggregate extraction and transportation. Indeed, this emission causes sustainability concerns and environmental issues [1] [2]. Another environmental problem which is related to the industry of construction is the accumulation of huge amounts of construction and demolition waste (CDW). Nowadays, such issues and concerns are recognized at the level of globe. Among these issues are the diminution of areas of landfills and exhaustion of the resources of the raw materials. To alleviate the negative influence of these environmental issues, there are various approaches [3]. One of these approaches is the employment of mineral admixtures such as Silica fume (SF) and fly ash (FA) in the production of concrete. These are by-product materials which can be used to replace ordinary Portland cement (OPC) [4]. The use of such materials can greatly help in reducing consumption of cement which in turn may substantially contribute to reduce the environmental related issues. Another way is the reuse or recycle of CDW to be used as fine or coarse aggregates instead of traditional aggregate. Crushed concrete, for example, can be used as recycled coarse aggregate in the concrete manufacture. This is also very helpful in conserving our environment [5] [6].

The concrete that includes recycled coarse aggregate (RCA) is called recycled aggregate concrete (RAC). Although the use of RCA in producing RAC is beneficial


in terms of sustainability and environmental impact, its behavior is not as good as the natural aggregate concrete (NAC) [7]. It has been reported that RAC shows lower performance than that of NAC. RCA affects both conditions of concrete, fresh and hardened. RCA diminishes the workability of concrete and decreases its mechanical properties [3]. Concrete’s strengths including compressive strength, splitting tensile strength and flexural strength may reduce by up to 40%, 25% and 20% in comparison to NAC, respectively [8]. The previous studies have related this behavior to the low quality of RCA. RCA comprises natural aggregate with mortar attached to its surface which is porous and characterized with micro-cracks [9]. These characteristics result in a weak RCA with high water absorption and porosity. Such characteristics (high porosity and water absorption) result in lower workability of RAC compared to NAC [3] [10] [11].

The previous studies on the use of SF in NAC have shown that such mineral admixture has a characteristic of the pozzolanic reaction. As a results of this reaction, such mineral materials admixture can improve the mechanical properties and enhance the durability of concrete (NAC) [6] [12] [13].

Therefore, this experimental work examines the effect of using SF at different contents as OPC replacement on the performance of RAC. In this RAC, the natural coarse aggregate is fully replaced with RCA originated from crushing old concrete elements. This study investigates the workability and the mechanical properties of RAC comprising different contents of SF.

2. Experimental Work 2.1. Materials

Normal Portland cement (OPC) type CEM I meeting specifications of BS EN 197 was employed in current study. The chemical composition of the OPC, as provided by the provider, is displayed in Table 1.

Silica fume was used in the current study as mineral admixtures to substitute the OPC. Table 2 displays the properties (physical) of the OPC and SF while the chemical oxides contents of the SF are shown in Table 1, as supplied by the provider.

The coarse aggregate employed in this study can be divided into two types. The first one is natural gravel extracted from the river in the region of Kalak area in Erbil city. It is rounded gravel with a maximum size of 20mm. The second one is recycled aggregate originated from crushing the debris of demolished concrete structures, see Figure 1. Just as the natural gravel, the recycled one has the same maximum aggregate size of 20mm. Some of the physical properties of these aggregates employed in the current work are shown in Table 3.

The fine aggregate utilized in current study is river sand extracted from the river in Kalak area in Erbil city. It had a maximum size of 4.75 mm.

Superplasticizers were used in this study to attain appropriate workability for the concrete mixtures. Slump test was conducted to evaluate the workability of all mixes. The superplasticizer used is a solution contains polymers called poly-carboxylate ether (PCE).

Table 1. Composition of OPC and silica fume (SF) used in current study

Material SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2O Na2O

CEM I 21.04 4.83 3.01 66.5 0.76 2.65 0.35 0.52 0.56

SF 93.4 0.8 1.5 0.8 0.2 - 0.72 0.70 -

Table 2. Physical properties of the OPC and SF

Property OPC SF

Specific gravity 3.15 2.3

Fineness (m2/kg) 446 13200

Initial setting time (min) 100 -

Table 3. Physical properties of coarse aggregates (CA)

Coarse aggregate Type Property

Shape Surface texture Specific gravity (SSD) Water absorption (%)

Natural Rounded Smooth 2.67 1.1

Recycled Angular Rough 2.46 4.6

1138 Recycled Aggregate Concrete Made with Silica Fume: Experimental Investigation

Figure 1. Coarse aggregate (Recycled) used in current study

Table 4. Designation of mixes and proportions of mixes (kg/ m3)

Number Mix code C SF W CA

FA Natural Recycled

1 NSF0 355 0 170.4 1096 0 739

2 RSF0 355 0 170.4 0 1034 739

3 RSF5 337.25 17.75 170.4 0 1034 739

4 RSF10 319.5 35.50 170.4 0 1034 739

5 RSF15 301.75 53.25 170.4 0 1034 739

6 RSF20 284.00 71.00 170.4 0 1034 739

C= Cement;SF= Silic fume ; W=Water,CA= Coarse aggregate; FA= Fine aggregate

2.2. Proportioning of Mixes, Mixing and Casting

The total number of mixes examined in this study is six mixes. Table 4 includes detailed information about the mixes such as mix number, mix designation and composition of all mixes. All mixes were made with same ratio of water/cement (w/c) which is (0.48). A constant quantity of superplasticizer was added to all mixtures to attain a proper workability. This quantity is equal to 0.4% of cement mass.

The process of mixing included several steps. Firstly, all aggregates (coarse and fine) were placed in the pan of the mixer and mixed for 2 minutes. Secondly, the binders were included and mixing continued for 2 more minutes. Thirdly, water and chemical admixtures were put in the mixer and mixing continued for 3 minutes. The concrete ingredients were blended in a mixer that had a 0.1 m3capacity. After mixing and assessing the workability of concrete, the concrete in fresh state was cast in different types of molds and compacted. An internal vibrator was used for the compaction process. Different types of molds were used to cast the concrete. Three 100 mm cubes, three cylinders 100×200 mm and three prisms 100×100×500 mm were cast for each mix. After casting and compaction, all molds were concealed using nylon sheets and left to cure for 24 hrs. Thereafter, the concrete samples were demolded and moved to water tank where kept for further curing till the day of testing.

2.3. Experiments

Assessment of workability (Slump Test)

In order to evaluate workability of fresh concrete for all mixtures, slump test was undertaken, see Figure 2. The test of slump was conducted as per BS EN 12350-2 [14].

Figure 2. Test of Slump

Compressive strength Assessment

The compressive strength test was carried out as per the specifications of BS EN 12390-3 [15]. The concrete samples (cubes) were assessed for compression after 28 days of water curing. A hydraulic machine for compression loading having capacity of 2000 KN was utilized in this


test.

Figure 3. Concrete cube before testing under compression

Splitting tensile strength Assessment

The test of splitting tensile strength was conducted as per specifications of standard test of BS EN 12390-6 [16]. The samples of the test were cylinders having dimensions of 100×200 mm. The test was conducted for the samples after 28 days of curing in water. Figure 4 displays the machine used for the test.

Figure 4. Concrete sample for splitting tensile strength test.

Test of flexural strength

The flexural strength test was conducted as per the requirements of BS EN 12390-6 [17]. The concrete samples (prisms) were tested for flexural at age 28 days. A machine for bending having 100 KN capacity was utilized in this test, see Figure 5. The concrete beams were assessed for bending over a length of 300 mm.

Figure 5. Bending machine used for flexural strength

3. Results of Tests and Discussions

3.1. Results of Workability

The workability of all mixes was assessed using slump test. The results (in mm) of this test for all mixtures are displayed in Table 5 and shown in Figure 6. In this table, the normalized slump (slump value of mix divided by the slump value of mix NSF0 or mix RSF0) are also presented. The normalized values are used to compare the results of the mixes with the results of these two reference mixes.

Table 5. Slump test results (values) and the normalized slump compared to mix NSF01 and RSF02

Mix Slump Test Results

Slump mm Normalized1 Normalized2

NSF0 110 1.0 -

RSF0 90 0.82 1.0

RSF5 90 0.82 1.0

RSF10 80 0.73 0.89

RSF15 65 0.59 0.72

RSF20 55 0.50 0.62

Figure 6. Results of slump test


The replacement of NCA with recycled aggregate decreases the workability of the concrete as the slump value reduced from 110 mm (for mix NSF0) to 90 mm (for mix RSF0) as can be noticed in Figure 6. This means that workability of mix NSF0 reduced by 18% when the RCA was used instead of NCA (see normalized workability in Table 5). This is mainly because of the high capacity of RCA to absorb water (see Table 3) and its rough surface. Studies such as [3] [18] reported similar negative effects of RCA on the workability of concrete. The use of SF also had adverse effect on workability of RAC. This adverse effect depends on the content of the SF as the adverse effect increases with the increase of the content of SF as can be seen Table 5. For instant, compared to the slump value of mix SF0, mixes RSF5, RSF10, RSF15 and RSF20 exhibited lower slump values by 18%, 27%, 39% and 50%, respectively. This behavior is caused by high surface area of silica fume which demands high quantity of water to maintain the workability of the concrete [9].

3.2. Results of Compressive Strength

For each mix, 3 cubes were tested under compression load to assess the performance of all mixes under compression loading. The results (average of 3 samples) from concrete mixtures are displayed in Table 6 and depicted in Figure 7. The normalized values for the compressive strength are used to compare the results of the mixes with the results of the two reference mixes, SF0 and RSF0.

Table 6. Compressive strength test results with normalized strength compared to mix NFS01 and RFS02

Mix Compressive strength Test Results

Values MPa Normalized1 Normalized2

NSF0 38.8 1.0 - RSF0 27.7 0.71 1.0 RSF5 31.8 0.82 1.14

RSF10 35.7 0.92 1.29 RSF15 37.5 0.97 1.35 RSF20 40.1 1.03 1.45

Figure 7. Results of compressive strength of all mixes

Table 6 indicates that the usage of recycled coarse

aggregate diminishes the strength of the concrete. For instance, the compressive strength of the mix NSF0 decreased form 38.8 MPa to 27.7 MPa when the NCA was replaced with RCA (mix RSF0). This means that the strength of concrete decreased by up to 29% when RCA was used (see Table 6). This decrease is due to the low performance of RCA as its particles are weak, porous and lighter than NCA; hence leading to lower compressive strength [3] [11].

The substitution of OPC with SF resulted in compressive strength (at 28days) improvement. The content of the silica fume had direct effect on the amount of strength improvement (see Figure 7). For example, the compressive strength of mix RSF0 improved from 27.7 MPa to 31.8, 35.7, 37.5 and 40.1 MPa, when the OPC was replaced with 5%, 10%, 15% and 20% of silica fume, respectively. These values, compared to that of mix RSF0, represent strength improvement of 14%, 29%, 35% and 45% for the mixes RSF5, RSF10, RSF15 and RSF20. Therefore, by replacing OPC with SF at content between 15-20 %, comparable strength to that of the NAC, can be achieved. The positive effect of silica fume on the strength performance of RAC was also reported by [13] [19]. The strength enhancement of the RAC due to the utilization of SF can be mainly attributed to the pozzolanic reaction and partly to the filling capability of this material because of it very small particles [20]. The chemical reaction of the SF (pozzolanic reaction) can result in more calcium silicate hydrate gel; resulting in a stronger concrete [6] [13] [11]. Furthermore, owing to its fine-particles, silica fume has the potential to play a crucial role in filling the micro-voids and pores of the surface of the RCA and in adjusting the microstructure of the concrete; hence leading to denser concrete. Certainly, such mechanism can help in improving the density of the concrete and; thus enhancing concrete’s compressive-strength [21] [22] [23].

3.3. Results of Splitting Tensile Strength

Three concrete samples with cylindrical shape were assessed to evaluate the splitting ensile strength for each mix. The results (average of 3 samples) from concrete mixtures are presented in Table 7 and depicted in Figure 8. Normalized values of the splitting tensile strength are employed to make a comparison between results of all other mixes and results of the two reference mixes, SF0 and RSF0.

Table 7. Splitting tensile strength results including normalized values (compared to SF01 and RSF02)

Mix Splitting tensile

Strength MPa Normalized1 Normalized2 NSF0 3.30 1.0 - RSF0 2.77 0.84 1.0 RSF5 2.86 0.87 1.03 RSF10 3.14 0.95 1.13 RSF15 3.26 0.99 1.18 RSF20 3.57 1.08 1.29


Figure 8. Results of splitting tensile strength

Just as the trend of the outcomes of the compressive strength, the results of splitting tensile strength show lower values for mixes without SF and comparable or larger values for mixes with SF. It is clear from Table7, that mix RSF0 which is made with RCA had splitting tensile strength of 2.77 MPa, whereas mix NSF0 showed strength value of 3.3 MPa. This means that when the NCA was replaced with RCA, the splitting tensile strength of the concrete decreased by up to 16% (see normalized value in Table 7). This reduction is attributed to the low characteristics of RCA such high porosity and low density [13] [18].

Figure 8 shows that when SF was used, enhancement in the splitting tensile strength was observed. For instance, when 5%, 10%, 15% and 20% of SF were used instead of the OPC, the splitting tensile strength increased by 3%, 13%, 18% and 29%, respectively, comparing to the strength of the mix RSF0. Also, comparable (to that of mix NSF0) splitting tensile strength was achieved at SF content of 15% and higher by 8% at SF content of 20% (see Table 7). Hence, silica fume at contents of 15-20 % can be used instead of OPC to obtain RAC that has similar strength in splitting tensile to that of the mixture made with NCA. The improvement in splitting tensile strength can be associated with the pozzolanic reaction and filling ability of SF [13]. The filling ability of the small particles of the SF can reduce the negative effect of the micro-cracks on the RCA; resulting in better splitting tensile strength for the RAC [22-25].

3.4. Results of Flexural Strength

Three prisms were tested under bending to evaluate the tensile strength in flexural for all mixes after 28 days of water curing. The outcomes (average of 3 samples) are illustrated in Table 8 and Figure 9. Normalized values of flexural strength are employed to make a comparison between results of mixes with the results of the two

reference mixes, NSF0 and RSF0.

Table 8. Flexural strength results including normalised values (compared to SF01 and RSF02)

Mix Flexural Strength

Strength MPa Normalized1 Normalized2

NSF0 4.27 1.0 -

RSF0 3.60 0.84 1.0

RSF5 3.75 0.88 1.04

RSF10 4.14 0.97 1.15

RSF15 4.24 0.99 1.18

RSF20 4.49 1.05 1.25

Figure 9. Results of the flexural strength of all mixes

From Table 8, it can be said that the trend of the outcomes of both compressive strength and the flexural strength are alike. The flexural strength of natural aggregate concrete (mix SF0) declined from 4.27 MPa to 3.60 MPa when recycled coarse aggregate was used (mix RSF0) as cane be seen in Figure 9. This decrease in flexural strength of mix RSF0 is about 16% lower than that of the mix SF0. The decline in this strength can also be attributed to the same weaknesses of the RCA mentioned in section 3.2 and 3.3. Similar to the case of the splitting tensile strength, the addition of SF had a beneficial effect on the flexural strength of the mixes made with RCA. The flexural strength increased from 3.6 MPa (for mix RSF0) to 3.75, 4.14, 4.24 and 4.49 MPa when 5%, 10%, 15% and 20 % of OPC was replaced with SF, respectively. In another word, the addition of 5%, 10%, 15% and 20 % of SF increased the flexural strength by 4%, 15%, 18% and 25%, respectively in comparison with mix RSF0 as can be seen in Table 8. Also, flexural strength that is comparable to that of the mix NSF0 can be attained for the mixes with RCA if SF is added at content of 10-20 % of the OPC. This enhancement in the flexural strength of the RAC due to the inclusion of SF can be associated to the pozzolanic reaction [11] [13] [20].


4. Conclusions The discussion on the outcomes obtained in current

research can lead to these conclusions:- As a result of its high capacity to absorb water, high

porosity and its rough surface, recycled aggregate (coarse) diminish the workability of concrete. The inclusion of SF increases this diminish in the workability of the RAC due to the high surface area of its particles. The decline in the workability can reach 50%.

All strengths decrease when RCA is used. The diminish in the compressive strength, tensile strength and flexural strength is about 29%, 16% and 16% respectively. The weaknesses of the recycled-coarse aggregate are the key reason for this behavior.

Replacing OPC with silica fume possess a beneficial influence on compressive strength, splitting tensile strength and flexural strength of RCA mixtures. The pozzalnic reaction of the SF particles is the prime reason behind the strength enhancement.

Close strength to that mixture incorporating NCA will be obtained if silica fume is replaced with OPC at contents between 10-20%. Thus, the use SF can encourage the utilization of recycled coarse aggregate.

Acknowledgments We would like to thank Erbil Polytechnic University

and Tishk International University for their support and help.

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