Moses-final Project Report

8/9/2019 Moses-final Project Report

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JOMO KENYATTA UNIVERSITY OF

AGRICULTURE AND TECHNOLOGY

Department of Civil, Construction and Environmental Engineering

ECE 2505: FINAL YEAR PROJECT REPORT

TITLE:

DETERMINING EFFECT OF SISAL FIBRE REINFORCEMENT IN STRUCTURAL

CONCRETE INCORPORATING RECYCLED CONCRETE AGGREGATE AS THE

COARSE AGGREGATE

BY:

MOSES AWUOR

REG. NO: E25-0894/05

SUPERVISED BY: Eng. MUSIOMI

This project report is submitted in partial fulfillment for the award of a Bachelor of Science degree

in Civil Engineering of Jomo Kenyatta University of Agriculture and Technology.

DECEMBER 2010


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DECLARATION

I, Awuor Moses, do declare that this report is my original work and to the best of my knowledge, it

has not been submitted for any degree award in any University or Institution.

Signed_______________ Date ____________

CERTIFICATION

I have read this report and approve it for examination.

Signed_______________ Date_____________


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ACKNOWLEDGEMENT

My fervent thanks go to my supervisor Eng Musiomi who assisted me tirelessly, Civil Engineering

staff members and my colleagues who guided and assisted me throughout my studies and in

accomplishing this research work. Special thanks to all staff at the structural laboratory, in

particular Mr. Kamamia, Mr. Ayugi and Mr. Obadiah. In addition, I would like to thank my familyand friends who stood by my side throughout my studies.


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ABSTRACT

The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the

engineering properties of the basic materials, such as fracture toughness, flexural strength and

resistance to fatigue, impact, thermal shock and spalling. Investigations have been carried out in

many countries on various mechanical properties, physical performance and durability of cement

based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo

and wood fibres. These fibres have always been considered promising as reinforcement of cement

based matrices because of their availability, low cost and low consumption of energy. In this

review, the general properties of the composites are described in relation to fibre content, length,

strength and stiffness. The production of sisal fibres as compared with synthetic fibres or even

with mineral asbestos fibres needs much less energy in addition to the ecological, social and

economical benefits.

World over there is an increased availability of demolished concrete from construction and

demolition waste that can be used to produce recycled concrete aggregate (RCA). Using the waste

concrete as RCA conserves virgin aggregate, reduces the impact on landfills, decreases energy

consumption and can provide cost savings; all in concurrence with principles of sustainable

development. The conventional class 20 concrete contains cement, river sand and natural

aggregate in the ratio of 1:2:4 respectively. In this research, the natural aggregate was totally

replaced with recycled concrete aggregate and the optimum amount (by mass) of sisal fibre

determined, using an optimal length of 35mm.


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TABLE OF CONTENTS

DECLARATION ........................................................ ................................................................. ................................................ ii

CERTIFICATION ...................................................................................... ................................................................. ............... ii

ACKNOWLEDGEMENT ..................................................................................... .............................................................. ...... iii

ABSTRACT ................................................................................................................................................................................ iv

TABLE OF CONTENTS ...................................................... ................................................................. ..................................... v

LIST OF TABLES ...................................................... ................................................................. .............................................. vii

LIST OF FIGURES ............................................................... ................................................................. .................................. viii

LIST OF APPENDICES .................................................................................................. .......................................................... ix

ABBREVIATIONS AND ACRONYMS ............................................................... .............................................................. ....... x

CHAPTER ONE ........................................................................................................................................................... 1

1.0 INTRODUCTION ............................................................. ................................................................. ..................................... 1

1.1 Topic Background ................................................................................................................................................................... 1

1.2 Problem Statement ............................................................. ................................................................. ..................................... 2

1.3 Study Justification ................................................................................................................................................................... 2

1.4 Objectives ................................................................ ................................................................ ................................................ 3

CHAPTER TWO .......................................................................................................................................................... 4

2.0 LITERATURE REVIEW ............................................................................................. ........................................................... 4

2.1 Physical and Mechanical Properties of Composites ................................................................ ................................................ 6

2.2 Sisal Fibre Production Technology.......................................................................................................................................... 6

2.3 Construction and Demolition Waste ........................................................ ................................................................. ............... 6

2.4 Concrete Recycling.................................................................................................................................................................. 7

2.5 Merits of Using RCA ......................................................... ................................................................. ..................................... 7

2.6 Barriers to Using RCA ............................................................................................................................................................ 8

2.7 Properties of RCA ................................................................................................................................................................... 8

CHAPTER THREE .................................................................................................................................................... 12

3.0 RESEARCH METHODOLOGY .......................................................................................................................................... 13

3.1 Material Sampling and Preparation ....................................................................................................................................... 13

3.1.1 Cement ......................................................... .............................................................. ......................................................... 13

3.1.2 River Sand .......................................................................................................................................................................... 13

3.1.3 Recycled Concrete Aggregates ............................................................. ...............................Error! Bookmark not defined.

3.1.4 Sisal Fibres ......................................................................................................................................................................... 13

3.2 Gradation Test/ Sieve Analysis ............................................................... ................................................................. ............. 14

3.3 Density Tests ......................................................................................................................................................................... 14

3.4 Moisture Absorption .......................................................... ................................................................. ................................... 14

3.5 Mix Design ............................................................................................................................................................................ 14

3.6 Compacting Factor Test (Workability) ............................................................... .............................................................. ..... 15

3.7 Strength Tests ........................................................................................................................................................................ 15

3.7.1 Compressive Strength ..................................................... ................................................................. ................................... 15

3.7.2 Tensile Strength .................................................................................................................... .............................................. 15CHAPTER FOUR ....................................................................................................................................................... 16


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4.0 RESULTS ..............................................................................................................................................................15

4.1 Sieve Analysis. ........................................................................................................................................................16

4.2 Specific Gravity and Water Absorption. ....................................................................................................................17

4.3 Slump Test. ................................................................ .............................................................. .............................................. 18

4.4 Compressive Strength Test. .......................................................... ................................................................. ........................ 19

4.4.1 Strength Development ................................................................................................ ........................................................ 20 4.5 Density of Concrete ................................................................................................................. ................................................ 2

4.6 Flexural Strength. .................................................................................................................................................................. 22

CHAPTER FIVE ........................................................................................................................................................ 25

5.0 CONCLUSION AND RECOMMENDATIONS .............................................. ............................................................... ..... 25

5.1 Conclusions ........................................................................................................................................................................... 25

5.2 Recommendations ................................................................................................................................................................. 25

REFERENCES .......................................................................................................................................................................... 26


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LIST OF TABLES

Table 2.1- Results for aggregate tests (Kasai, 1994) ……………………………………………...11

Table 2.2- Requirements for RCA and NCA ……………………………………………………..11 Table 4.1- Specific gravity & Water absorption tests on aggregate……………………………….17

Table 4.2- Slump test results……………………………………………………………………….18

Table 4.3- Compressive strength test results………………………………....................................18

Table 4.4- Measured density of concrete at 28 days……………………………………………….21

Table 4.5- Flexural strength test results at 28 days………………………………………………...23

Table 5.1- Fine aggregate sieve analysis results…………………………………………………...28

Table 5.2- RCA sieve analysis results……………………………………………………………..28

Table 5.3- Specific gravity & Water absorption results, fine aggregate…………………………..29

Table 5.4- Specific gravity & Water absorption results, RCA…………………………………….30

Table 5.5- Concrete mix design……………………………………………………………………31

Table 5.6- Mixing proportions, 0% sisal fibre……………………………………………………..33

Table 5.7- Mixing proportions, 0.2% sisal fibre…………………………………………………...33

Table 5.8- Mixing proportions, 0.5% sisal fibre…………………………………………………...33

Table 5.9- Mixing proportions, 1% sisal fibre……………………………………………………..33

Table 5.10-Raw compressive strength test results…………………………………………………34

Table 5.11- Raw flexural strength test results…………………………………………………......34


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LIST OF FIGURES

Figure 2.1- Recycled Concrete Aggregates …………………………………………………..12

Figure 2.2- Natural Coarse Aggregates ………………………………………………………12

Figure 2.3- The sisal plant (a), leaf (b) and leaf cross-section (c)…………………………….12

Figure 4.1- Fine aggregate sieve analysis results……………………………………………...16

Figure 4.2- RCA sieve analysis r esults………………………………………………………...17

Figure 4.3- Slump vs sisal fibre content……………………………………………………….18

Figure 4.4- Compressive strength, 7days………………………………………………………19

Figure 4.5- Compressive strength, 28days……………………………………………………..20

Figure 4.6- Strength development………………………………………………………………21

Figure 4.7- Measured density of concrete at 28 days…………………………………………..22

Figure 4.8- Flexural strength test results at 28 days…………………………………………….23

Figure 4.9- Beam flexure testing………………………………………………………………..24


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LIST OF APPENDICES

APPENDIX A- SIEVE ANALYSIS……………………………………………………………..28

APPENDIX B- SPECIFIC GRAVITY & WATER ABSORPTION, FINE AGGREGATE……29

APPENDIX C- SPECIFIC GRAVITY & WATER ABSORPTION, RCA……………………..30

APPENDIX D- MIX DESIGN……………………………………………………………………31

APPENDIX E- MIXING PROPORTIONS……………………………………………………….33

APPENDIX F- COMPRESSIVE STRENGTH TEST RESULTS………………………………..34

APPENDIX G- FLEXURE TEST RESULTS……………………………………………………..34


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ABBREVIATIONS AND ACRONYMS

AASHTO – American Association of State Highways and Transportation Officials

BS – British Standards

C&DW – Construction and Demolition Waste

CSI – Cement Sustainability Initiative

DN- Daily Nation

ITZ – Interfacial Transition Zone

JKUAT – Jomo Kenyatta University of Agriculture and Technology

NCA – Natural Coarse Aggregate

NEMA – National Environmental Management Authority

NRMCA – National Ready Mixed Concrete Association

PCC – Portland Cement Concrete

RCA – Recycled Concrete Aggregate

SSD – Saturated and Surface Dry

TxDOT – Texas Department of Transportation UK – United Kingdom US – United States of

America

BRU-Building Research Unit

OPC – Ordinary Portland Cement


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CHAPTER ONE

1.0 INTRODUCTION

1.1 Topic Background

Cement composites reinforced with unidirectional aligned sisal fibres present a tension hardening

with multiple cracking behaviour. The multiple cracking behaviour achieved by this composite is

governed by interfacial bond characteristics between fibre and matrix. Naaman and Najm (1991)

states that there are four main factors that influence the bond adhesion: physical and chemical

adhesion; mechanical component of bond such as deformed, crimped and hooked end fibres; fibre-

to-fibre interlock, and friction.

Peled and Bentur (2003) investigated the pull-out behaviour of straight and crimped polyethylene

yarns. They found that increasing the crimp density enhances the mechanical anchoring and the

equivalent adhesion bond strength increases from 1 to 1.84 Mpa (10 mm embedded length). The

bond properties of carbon in cementitious matrices were investigated by Katz et al. (1995). Carbon

fibres with diameters of 10 and 46 μm were tested. Different matrices were used and the mean

bond strength for 10 and 46 μm ranged from 0.52 to 1.29 M pa and 0.39 to 3.02 Mpa, respectively.

Sisal fibres are naturally modified by nature presenting different mechanical components of bond.

Sisal is a flexible fibre that presents irregular cross-section area. The sisal fibres can be divided

into 3 types of bond mechanical components: horse-shoe shape – these represents the majority of

the fibres that can be found in the sisal plant leaf and present small areas; arch shape – presentlarger areas and are found in a less content than the horse-shoe shape; and twisted arch shape – a

result of the fibre extraction process. The sisal fibres are extracted from its leaf by a mechanical

process called decortication. In this process, sometimes, the arch shape fibres can brake and twist

resulting in the third type shape. Besides the different shape the sisal fibres also present a

corrugated surface that may be beneficial to the fibre-matrix adhesion.

Apart from the fibre, any construction activity requires several materials such as concrete, steel,

brick, stone, glass, clay, mud, wood, and so on. However, the cement concrete remains the main

construction material used in construction industries. For its suitability and adaptability with

respect to the changing environment, the concrete must be such that it can conserve resources,

protect the environment, economize and lead to proper utilization of energy. To achieve this, major

emphasis must be laid on the use of wastes and byproducts in cement and concrete used for new

constructions. When concrete structures are demolished or renovated, the rubble is most

commonly used as landfills.

The selection of aggregates used in concrete is important since it makes up approximately 60% to

75% of the total volume of concrete. Aggregates should consist of particles with adequate strength

and resistance to exposure conditions and should not contain materials that will cause a chemical


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reaction with the paste that may lead to deterioration of the concrete. Recycled concrete aggregate

is defined as recycled aggregate principally comprising crushed concrete (BS 8500-1:2002).

Conventional concrete aggregate consists of sand (fine aggregate) and various sizes and shapes of

gravel or stones. However, there is a growing interest in substituting alternative aggregate

materials, largely as a potential use for recycled materials. This has been precipitated by a decline

in good quality aggregate available for construction while on the other hand there is an increase in

demolition waste. This is especially being felt in developed countries. Worldwide, approximately

eight to eleven billion tones of aggregate (sand, gravel, and crushed rock) are being used for

concrete production every year. With the rapid development expected in Kenya as the country

seeks to become a middle income country, there is going to be increased pressure on the natural

mined aggregate in the country. Conversely, the amount of demolished concrete is likely to

increase. This will be from demolition of structures that lie on public land earmarked for

infrastructural development projects like roads. In addition, some buildings may be deemed

obsolete and may need to be demolished. Other sources of waste concrete that can be used to

produce RCA include waste from concrete testing laboratories, production waste at a pre-cast

production facility, waste from construction and demolition, returned concrete which is fresh (wet)

from ready-mix trucks and areas undergoing reconstruction following war or natural calamities.

This research therefore intends to utilize the promising properties of sisal fibre to improve the

physical properties of structural concrete by reinforcement incorporating RCA as coarse aggregate.

1.2 Problem Statement

The need for environment friendly sources of construction materials cannot be overemphasized.

Recycled concrete aggregate, one such material, is seen to be usable as a substitute for

conventional natural coarse aggregate in concrete. This research therefore intends to utilize the

promising properties of sisal fibre to improve the physical properties of structural concrete by

reinforcement incorporating RCA as coarse aggregate.

1.3 Study Justification

Although there is a critical shortage of natural aggregate, there is an increasing amount of

demolished concrete. The environmental impact of waste concrete is significant as is the

environmental impact of mining conventional aggregate. Not only is there the environmental

impact of transporting the waste concrete away from the site but the waste concrete also fills up

valuable space in landfills. There is a huge potential to reuse this material as a source of newaggregate. Recycling concrete, from deteriorated concrete structures, would reduce the negative


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impact on the environment and increase sustainability of aggregate resources. There are both

environmental and economic benefits to using recycled concrete aggregate. Using RCA conserves

virgin aggregate, reduces the impact on landfills and decreases energy consumption. It is estimated

that using RCA can save up to $11 per 1000 kg ($10 per ton) of aggregate. (American Concrete

Pavement Association, 1993).

The readily availability of sisal in the developing countries further justifies the appropriateness of

this study.

1.4 Objectives

(a)General Objective

To evaluate structural performance of sisal fibre reinforcement in concrete incorporating recycled

concrete aggregate as course aggregate.

(b)Specific Objectives

1) To determine the physical material properties of sisal fibre reinforced concrete with

recycled concrete coarse aggregates.

2)

To carry out mix design of concrete utilizing sisal fibre reinforcement and recycled

concrete aggregate as course aggregate.

3) To establish the optimum amount by mass and size by length of the sisal fibres utilizing

sisal fibre reinforcement and recycled concrete aggregate.


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CHAPTER TWO

2.0 LITERATURE REVIEW

Fibres have been used to toughen bricks and pottery since the very beginning of civilization, but

only in the last twenty five years have the principles of fibre reinforcement of brittle matrices

began to be scientifically understood. Initially, it was suggested that the cracking strain of brittle

matrices, such as cement paste mortar and concrete, could be significantly increased by using

closely spaced fibres (Romauldi & Batson, 1963). The experimental studies showed that the stress

at which a brittle matrix will crack can be slightly increased by using high modulus fibres but, in

general, the cracking strain of the matrix remains unaltered. Considerable modification in the

behavior of the material was observed once the matrix has been cracked. The fibres bridge across

the cracks and so provide post-cracking ductility. Although the strain at cracking does not increase

due to fibre reinforcement, the tensile strain at rupture does, resulting in a tough material with high

resistance to impact loading (Bentur & Mindess, 1990).

Fibres can be added to cement based matrices as primary or secondary reinforcement. Fibres work

as primary reinforcement in thin products in which conventional reinforcing bars cannot be used.

In these applications, the fibres act to increase both the strength and the toughness of the

composite. In components such as slabs and pavements, fibres are added to control cracking

induced by humidity or temperature variations and in these applications they work as secondaryreinforcement (Tolêdo Filho, 1997).

In cement based composites the two major roles played by the fibres are to improve the toughness

and the post-cracking performance of the matrices. There is also some changes created to the pre-

cracking behavior of the hardened matrix, which help to define the composite action. Fibre content

(% by volume), ratio of fibre modulus, Ef , to the matrix modulus, Em, and the

ratio of fibre strength, sf , to the matrix strength, sm, all influence the performance of the

composite before and after cracking (England & Tolêdo Filho, 1997; Tolêdo Filho, 1999). In a

well designed composite the fibres can serve two functions in the post-cracking zone (Bentur &

Mindess, 1990): (i) to increase the strength of the composite over that of the matrix by providing a

means of transferring stresses and loads across the cracks and (ii) to increase the toughness of the

composite by providing energy absorbing mechanisms related to the debonding and pull-out

processes of the fibres bridging the cracks.

2.1 Physical and Mechanical Properties of the Composites

Joseph et al. (1999) reported that sisal is one of strongest vegetable fibres and several studies have

been reported in the literature based on its use as reinforcement in cement matrices (BRS, 1970;


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Nilsson, 1975; Zonsveld, 1975; Mukherjee & Satyanarayana, 1984; Gram, 1983; Aziz et al.,

1984). Studies of sisal fibre reinforced concrete were started in Sweden in 1971 by Nilsson (1975).

Cut fibres with a length of 10- 30 mm were cast into beams and an improvement in the tensile

strength in bending was observed for fibre reinforced specimens. It was found that toughness

increased markedly when continuous fibre were used. In 1977 the Building Research Unit (BRU)

in Dar es Salaam started collaboration on the development of roof sheets on natural fibre

reinforced concrete with the Swedish Cement and Concrete Research Institute (Cappelen, 1978;

BRU, 1978; Mwamila, 1979, 1987; Mawenya & Mwamila, 1979). Test sheets were manufactured

for durability experiments. A special roof sheet profile was developed and several buildings in Dar

es Salaam have been provided with sisal fibre reinforced concrete roofs. The use of sisal fibre as

reinforcement in cement paste and concrete have been reported by Swift and Smith (1978; 1979a).

Their results on the flexural static strength and toughness of beams made of cement based matrices

reinforced indicated that remarkably high strengths can be achieved using suitable mixing and

casting techniques with optimum fibre volume fraction. They also found that impact resistance

can be improved by the addition of sisal fibres. Several application of this material was suggested

for low-cost housing and they produced corrugated sheets of 2140 x 690 x 7 mm in different ways

to optimize the processing technique. Guimarães (1984, 1987) has studied the influence of fibre

length and volume fraction, matrix proportioning and casting processes on the flexural strength,

water absorption and specific gravity of the sisal fibre-cement composites. An increase in the

flexural strength and better crack distribution was achieved by the incorporation of sisal fibres in

the cement matrices. They have studied the influence of casting pressure on the flexural properties

of the composites and it was found that 2.2 Mpa was the optional value. Morrissey & Coutts

(1985) have studied interfacial bonding between sisal fibres and cement matrices. To determine the

critical length of embedment, fibre lengths ranging from 10 to 60 mm were considered. It was

observed that in cement composites the critical length of embedment for sisal fibre was

approximately 30 mm. Mwamila (1985) has studied the behavior of sisal twines as main

reinforcement in concrete beams. The flexural performance was investigated under static, repeated

and sustained loading. An attempt to improve the beams performance was made by the use of short

sisal fibre to supplement the twines reinforcement. He concluded that the concrete beams

reinforced with twines presented poor cracking behavior, developing wide cracks and suffering

significant strength losses upon each crack occurrence. The residual and permanent deformations

and crack widths under repeated and sustained loads were also very significant. The use of short

sisal fibres to supplement the twines improved tensile toughness and, through bond enhancement

and stress redistribution, improved the tensile stiffen effect of the composite matrix. As a result thecracks formed were smaller, their propagation slow and the troughs in the strength-deflection


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curve removed. Further, the deformations under repeated and sustained load were significantly

reduced. Filho (1997) have studied both the short-term and long-term behavior of sisal fibre

reinforced mortar composites. The experimental work involved extensive laboratory testing to

study the influence of volume fraction, fibre length, fibre arrangement and matrix composition on

the mechanical properties of the composite. The workability of the fresh mix was shown to be

closely related to the volume fraction and fibre aspect ratio. An increase in fibre volume fraction

and fibre length reduced the workability of the mix. It was established that, for volume fractions

smaller than 3% and fibre length smaller than 50 mm, the mixes could be manually compacted or

vibrated without balling.

2.2 Sisal Fibre Production Technology

The production technologies available include (Bentur & Mindess, 1990): combining fibres with

matrix in a pan mixer as if the fibres were an extra ingredient in the common method of producing

a cementitious mix; simultaneously spraying fibres and cement slurry onto the forming surface to

produce thin products fibre-reinforced concrete; dispersal of fibres in a cement slurry which is then

dewatered to produce thin products; hand-laying fibres, in the form of mats or fabrics, in moulds,

impregnating them with a cement slurry and then vibrating or compressing the mix to produce a

dense material with high fibre content; and impregnating continuous fibre mats and fabrics with a

cement slurry by passing them through a cement bath in a continuous process .

2.3 Construction and Demolition Waste

Worldwide, approximately eight to eleven billion tonnes of aggregate (sand, gravel, and crushed

rock) is being used for concrete production every year (Tarun, and Moriconi, 2005). Although

there is a critical shortage of virgin aggregate, the availability of demolished concrete for use as

RCA is increasing (Smith et al, 2008). Precise data on demolition waste is mostly available for

developing countries. According to the Cement Sustainability Initiative (CSI) report (2009, p. 3),

about 1.3 billion tonnes of waste are generated in Europe each year, of which about 40%, or 510

million tonnes, is construction and demolition waste (C&DW).The US produces about 325 million

tonnes of C&DW, and Japan about 77 million tonnes. Given that China and India are now

producing and using over 50% of the world’s concrete, their waste generation will also be

significant as development continues. In Kenya, there has been a government effort to reclaim land

that was grabbed by developers. In 2006, the government demolished about 60 structures at

Mlolongo to pave way for the expansion on Mombasa road. (East African Standard, 01 December

2006). The Daily Nation of 14

th

April 2009 reported that the government in conjunction with the National Environmental Management Authority (NEMA) intended to demolish structures


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encroaching in Kenya’s wetlands and river banks. It is imperative to note that the environmental

impact of this waste concrete is significant. Not only is there the environmental impact of

transporting the waste concrete away from the site but the waste concrete also fills up valuable

space in landfills. There is a huge potential to reuse this material as source of new aggregate

(Bairagi et al, 1990).

2.4 Concrete Recycling

Concrete recycling is a well established industry in many countries and most concrete can be

crushed and reused as aggregate. Existing technology for recycling by means of mechanical

crushing is readily available and relatively inexpensive. It can be done in both developed and

developing countries. With further research and development, the scope of applications for

recycled aggregate can be increased. However, even with existing technology, considerable

increases in recovery rates can be achieved in some countries with greater public acceptance of

recycled aggregate and reduction of misconceptions or ignorance about its possibilities for use

(CSI report, 2009) The Texas Department of Transportation (TxDOT) has been using recycled

concrete aggregate in Portland cement concrete highways for the past ten years. TxDOT has

learned that using RCA provides engineering, economic and environmental benefits. (US

department of transportation, 2004). Concrete recycling is becoming a popular way to deal with

demolition waste as indicated by the CSI report. Recycled aggregate accounts for 6% to 8% of

aggregate use in Europe. The greatest users are the United Kingdom, the Netherlands, Belgium,

Switzerland and Germany. It was estimated in 2000 that ~5% of aggregate in the US was recycled

aggregate. (CSI, 2009).

2.5 Merits of Using Recycled Aggregate

Several benefits can be accrued from use of recycled aggregates as has been shown in previous

research. Prime among them are the environmental benefits. (Torben et al, 1984) & (Oikonomou et

al, 2003) noted that recycling concrete, from deteriorated concrete structures, would reduce the

negative impact on the environment and increase sustainability of aggregate resources .Federal

Highway Administration, 2004) reported that using the waste concrete as RCA conserves virgin

aggregate, reduces the impact on landfills, decreases energy consumption and can provide cost

savings. Since recycled material can be used within the same metropolitan area, this can lead to a

decrease in energy consumption from hauling and producing aggregate, and can help improve air

quality through reduced transportation source emissions. They further noted that recycling of

aggregate was emerging as a viable option to solve the problem of dwindling virgin aggregate


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supplies. The same report also found that reuse of construction debris reduces unsightly stockpiles

of concrete rubble and animal infestation of stockpiles.

There are economic benefits of using RCA as there are environmental. Smith& Tighe, (2008)

affirm that there are both environmental and economic benefits to using recycled concrete

aggregate .Using RCA, creates cost savings in the transportation of aggregate and waste products,

and in waste disposal (Federal Highway Administration, 2004). It is estimated that using RCA can

save up to $11 per 1000 kg ($10 per ton) of aggregate, (American Concrete Pavement Association,

1993). CSI (2004, p17) summarizes the economic benefits of recycling aggregate thus; in an urban

environment concrete debris is hauled to a crushing site that is generally closer to the center of the

urban area than the virgin aggregate quarry. Industry comments were that the RCA stockpile is

usually closer to the job sites in an urban environment, thus less haul distance and less fuel burnt in

delivery. Production of virgin aggregate can use more fuel to crush due to larger initial size of rock

needing to be crushed to desired grade. Conversely, transportation costs may sometimes increase

when using recycled aggregate as it may not always be feasible to process aggregate on-site.

Another economic benefit is the recovery of steel from the recycling process (US Department of

Transportation, 2004).

2.6 Barriers to Using RCA

There are several barriers to overcome in order for RCA to become widely accepted. Initially,

there is a high investment cost to purchase concrete crushers. In addition, maintenance costs of

concrete crushers are also significant (Rashwan et al, 1997). Another barrier relates to the excess

amount of fine RCA created during the crushing process. This excess fine aggregate requires

disposal or an alternate use. Depending on the source and type of RCA, the absorption, strength,

and impurities vary. This can mean that it is unusable or that it might adversely impact the

concrete. There is a lack of knowledge on how RCA affects concrete durability since most studies

focus only on the properties of RCA concrete (Olorunsogo et al 2002). The other barrier is

lack of Specification and Guidelines. According to Kawano (n.d), there is no specification or any

guideline when using recycled concrete aggregate in the constructions. In many cases, the strength

characteristic will not meet the requirement when using recycled concrete aggregate.Therefore,

more testing should be considered when using recycled concrete aggregate.

2.7 Properties of Recycled Concrete Aggregates

Since at least three quarters of concrete is occupied by aggregate, its quality is of considerable

importance. The properties of aggregate greatly affect the durability and structural performance ofconcrete (Neville, 1981). (Dulaijan et al, 2002) found that the mechanical properties, namely


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compressive strength, split tensile strength, and elastic modulus of concrete specimens prepared

with different aggregates differed. Hence there is need to understand the properties of RCA as

aggregate and their effect on the subsequent concrete.

Absorption of recycled aggregates is considerably large amount, particularly, values of fine

aggregates shows approximately ten times that of river sand (Kikuchi et al, 1994). In general, the

RCA must be handled as a lightweight aggregate, which has higher water absorption. It is

important to maintain the aggregate in a moist saturated surface dry (SSD) condition to assure the

PCC mix water as designed is maintained so as to produce uniform plastic properties at constant

w/c ratio. Lightweight aggregate piles should be constantly sprayed with a garden sprinkler to

assure saturation (SSD) prior to batching. Maintaining a consistent and uniform SSD condition is

also a key to achieving a workable mix. Concrete made using RCA should need approximately 5%

more water than similar PCC with natural coarse stone (US Department of Transportation, 2004).

(Merelet et al, 1994) obtained concrete mixes by pre-humidifying the recycled concrete aggregates

using 30% of mixing water and by immersing them in water for 24 hours in order to saturate them.

The w/c ratio of these two mixes was 0.7. They found that their workability was greater than

concrete with a similar composition but on whose aggregates had not been moistened. The size of

RCA used in concrete can greatly affect the concrete performance. Fine RCA contains many

impurities and results in strength loss in the concrete. (Smith et al, 2008). Natural sand is used as

fine aggregate since it provides a greater strength than fine RCA (Poon et al, 2004). (Smith et al

2008) noted that since the concrete that the RCA was crushed from contained a maximum

aggregate size of 19 mm, this was the maximum size of the RCA that would be used in their

research. Any RCA over 19 mm would contain excess interfacial transition zones that would

negatively impact the strength of the concrete. (Poon et al 2004) confirm that RCA has a higher

interfacial transition zone (ITZ) due to its higher absorption and porosity. In order to minimize

negative effects on concrete performance from coarse RCA, it is important to limit the amount of

interfacial transition zones that are present in the RCA (Poon et al 2004).

Dulaijan et al, (2002) found that the mechanical properties, namely compressive strength, split

tensile strength, and elastic modulus, of concrete specimens prepared with different aggregate

quality differed. It is therefore expected that RCA containing concrete will not have the same exact

properties non-RCA containing concrete. Wainwright et al (1994) performed tests on the recycled

aggregate obtained from two laboratory sources concretes made of different strengths and found

that there was no clear relationship between the strength of the source concrete and the strength of

the RCA concrete. The majority of their work was concentrated on the mechanical or engineering

properties of the concrete and it has been shown that good quality concrete can be produced usingthe recycled concrete to replace the coarse fraction of the natural aggregates. When the recycled


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10

fines is used in combination with the recycled coarse there is often a reduction in the quality of the

resulting concrete due largely to the highly porous nature of this fine fraction. However the

properties of hardened concrete made with recycled coarse aggregates are inferior to those of a

control mix made with all natural materials. The situation is made worse when the natural fines are

replaced by recycled fines. Kikuchi et al, (1994) differ with (Wainwright et al, 1994). They assert

that the compressive strength, tensile strength, flexural strength and drying shrinkage of recycled

concrete are influenced directly by compressive strength of original concrete, however, it can be

considered that there is no effect of original concrete in case of compressive strength of new

concrete below 400kgf/cm2 (39.84N/mm2). Research has shown how various concrete properties

vary with inclusion of RCA in the mix. Since each source of RCA is unique based on its mix

design and environment, the test results and performance of RCA containing concrete can vary

greatly (Smith et al, 2008). It is generally accepted that concrete durability is reduced as the

amount of RCA is increased. RCA containing mixes are stiffer and lose workability faster than

mixes using virgin aggregates (Salem et al, 2003). Rashwan et al, (1997) corroborate that RCA

mixes have a decreased slump compared to virgin mixes with the same w/c ratio. The air content

in RCA containing mixes is higher than virgin mixes (Salem et al, 2003& Katz et al, 2003). Some

RCA containing mixes have a decreased compressive and flexural strength (Katz et al, 2003,

Shayan et al, and Xu, 2003 & Abou-Zeid et al ,2005), while others show an increased compressive

and flexural strength. Poon et al, (2002), Salem et al, (2003) & Katz et al, (2003) found that the

Modulus of Elasticity decreases with the use of RCA. Hansen et al, (1985), Ajdukiewicz et al,

(2002) & Tavakoli et al, (1996) further found that concrete containing RCA has a greater amount

of dry shrinkage than virgin aggregate concrete. Kikuchi et al, (1994, p. 34) summarize the

qualities of RCA thus;

i. Fineness Modulus: Fineness modulus of recycled coarse aggregates showed the similar value

as crushed stone by adjusting the particle distribution. For fine aggregate, considerable

differences are observed between recycled aggregates and river sand.

ii.

Specific gravity: For the range of specific gravity in dry condition of recycled aggregates,

coarse aggregates are from 2.32 to 2.35, fine aggregates are from 2.01 to 2.08, and these values

are smaller by about 10% compared with the crushed stone and river sand.

iii.

Absorption: Absorption of recycled aggregate is considerably large amount, particularly

values of fine aggregates showed ten times that of river sand.

Kasai (1994) summarized the physical test results of the recycled aggregate in the table below.


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11

Table 2.1 - Results for aggregate tests (Kasai, 1994)

He noted that recycled coarse aggregates comprise original coarse aggregates with attached mortar

and mortar rubbles. The quality of the recycled aggregates is affected by the mix proportion of the

original concrete, crushing process, grading control and the amount of impurities. Test resultsshow substantial scatter. These may be attributed to mortar component of the original concrete. An

agreeable quality may be obtained with a degree of substitution by recycled aggregate less than

30%. (Kasai, 1994) BS 8500-2-2002 has requirements for use of RCA as in the table below.

Table 2.2 - Requirements for Coarse RCA and NCA

Specific Gravity (dry) Water Absorption

%

Finess Modulus

Course Aggregate Range 2.09-2.5 1.75-10.07 6.64-7.72

Mean 2.30 5.79 6.85

Fine Aggregate

Range 1.98-2.20 4.79-13.20 2.86-3.99

Mean 2.07 9.73 3.29

Type of

Aggregate

Requirement

Max.

masonry

content

Mass

fraction %

Max. fines

Mass

fraction %

Max. light

weight

material

Mass fraction

%

Max.

asphalt

Mass

fraction

%

Max. other

material e.g.

glass, plastic,

metals

Mass fraction %

Max. acid

soluble

sulphate

SO3

Mass

fraction %

RCA 5.0 5.0 0.5 5.0 1.0 1.0

NCA 100 3 1 10 1 1

(a) Where the material to be used is obtained by crushing hardened concrete of known composition

that has not been contaminated by use, the only requirements are those for grading and maximum

fines.

( b) Material with a density less than 1000 kg/m3.


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fig 2.1- Natural course aggregate fig 2.2- Recycled concrete aggregate

The above figures (2.1 and 2.2) illustrate the difference between natural coarse aggregate and the

recycled course aggregate while the below one (fig. 2.3) shows the sisal plant, its leaf and leaf

cross-section showing different fibre types. The sisal plant leaf is a functionally graded composite

structure which is reinforced by three types of fibers: structural, arch, and xylem fibers. The first

occurs in the periphery of the leaf providing resistance to tensile loads. The others present

secondary reinforcement, occurring in the middle of the leaf, as well as, a path for nutrients.

Fig. 2.3- The sisal plant (a), leaf (b) and leaf cross-section showing different fiber types (c)


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13

CHAPTER THREE

3.0 RESEARCH METHODOLOGY

Experimental study design was employed and the main research method was laboratory research.

The sisal fibres used were obtained from Kano Plains, about 15Km east of Kisumu town. There is

plenty of sisal plants in this area with fibres attaining considerable lengths which was a

requirement during this study. Samples of concrete mixes containing RCA as the course aggregate

were made and subjected to the appropriate tests in the department’s Materials and structural

Laboratory. The main highlights of the methodology begun by collection and crushing of waste

concrete to obtain recycled concrete aggregate, then grading of aggregates according to BS 882

and determination of the specific gravity of the aggregates (natural fine and RCA). The water

absorption for the aggregates was also determined; then a mix design was carried out and slump

tests afterwards to determine workability. Finally, the strength properties of the cured concrete

specimen were established.

3.1 Material Sampling and Preparation

3.1.1 Cement

Ordinary portland cement satisfying BS12:1991 and KS-18-1: 2000 of average strength

32.5N/mm2 was used. Cement not being a variable item in the experiments was obtained from the

laboratory.

3.1.2 River Sand

River sand obtained from Machakos was used. Sieving was carried out to remove excess fines.

Also not a variable element in the experiments, hence one source was maintained.

3.1.3 Recycled Concrete Aggregates

RCA was obtained mainly from demolished structures along Thika Road as a result of the ongoing

reconstruction and expansion of the highway. Additional RCA was obtained from the crushed

waste concrete at the structures workshop. Absorption of RCA is considerably large amount

(Kikuchi et al 1994). Therefore RCA was handled as lightweight aggregates which have higher

water absorption. The RCA was maintained in a moist saturated surface dry (SSD) condition prior

to batching by constantly spraying with a garden sprinkler.


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14

3.1.4 Sisal F ibres

The sisal fibres to be used was obtained from Kano Plains, about 15Km east of Kisumu town.

There is plenty of sisal plants in his place with fibres attaining considerable lengths which was a

requirement during this study. The sisal fibres are extracted from its leaf by a mechanical process

called decortication. The production technologies available include (Bentur & Mindess, 1990):

combining fibres with matrix in a pan mixer as if the fibres were an extra ingredient in the

common method of producing a cementitious mix; simultaneously spraying fibres and cement

slurry onto the forming surface to produce thin products; fibre-reinforced concrete; dispersal of

fibres in a cement slurry which is then dewatered to produce thin products; hand-laying fibres, in

the form of mats or fabrics, in moulds, impregnating them with a cement slurry and then vibrating

or compressing the mix to produce a dense material with high fibre content; and impregnating

continuous fibre mats and fabrics with a cement slurry by passing them through a cement bath in a

continuous process. The first production technology was used. Other fibre properties assumed as

the instruments to measure them are not in the laboratory includes mean density, elastic modulus

and tensile strength of 0.9g/cm3, 19Gpa, and 500Mpa respectively. Diameter ranged from 0.005 to

0.5mm.

3.2 Gradation Test/ Sieve Analysis

This is the process of dividing a sample of aggregates into fractions of same particle size in order

to determine the size distribution of the aggregates. A sample of air dried aggregate was graded

according to BS 812: Part 1: 1975, by shaking a nest of stacked sieves, with the largest sieve at the

top for specified time so that the material retained on each sieve represents the fraction coarser

than the sieve in question but finer than the sieve above.

3.3 Density Tests

According to ASTM C 127-93, specific gravity is the ratio of mass of a unit volume of material to

the mass of the same volume of water at the stated temperature. The tests was carried out as per BS

812: Part 107.

3.4 Moisture Absorption

The porosity, permeability and absorption of aggregates influence the bond between it and the

cement paste, the resistance of concrete to freezing and thawing, chemical stability and specific

gravity. Moisture absorption was determined as per BS 812: Part 107: (Draft).

3.5 Mix Design

A conventional mix of cement, river sand and RCA in the ratio of 1:2:4 respectively and watercement ratio of 0.55 was prepared. Maximum size of RCA used was 20mm. Excess fines in RCA


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15

was removed by sieving through 4.76mm sieve to conform to requirements of BS 8500-2-2002

Table 2.4: RCA will be sprinkled with water before casting to achieve saturated surface dry

condition before casting.

The production technology applied was that of combining fibres with matrix in a pan mixer as if

the fibres were an extra ingredient in the common method of producing a cementitious mix. Four

mixes of varying amount of sisal fibre was prepared, then an optimum amount selected. An

optimum fibre length of 35mm was chosen, considering good workability the mix had as compared

to higher lengths.

3.6 Compacting Factor Test (Workability)

The test was done on each of the batches according to BS1881: Part 103: 1993 to establish the

amount of work necessary to produce full compaction.

3.7 Strength Tests

3.7.1 Compressive Strength

The test was carried out on the 150mm cubes at the Materials & structural laboratory according to

BS 1881: Part 116: 1983.

3.7.2 Tensil e Strength

The test was done on 150 X 150 X 500mm beams at the laboratory according to BS 1881: Part

118: 1983.


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CHAPTER 4

4.0 RESULTS

The data collected was analyzed and the processed data is presented in this chapter as follows.

4.1 Sieve Analysis

From the sieve analysis, the fine aggregate fitted into zone 2 grading according to Bs 882 1992.

The fine aggregate grading, upper and lower limits bounds are shown on fig 8. For the RCA, the

grading done fitted into the 5 – 20 mm size bracket for crushed aggregates according to table 3 of

BS 882 1992. BS 8500-2-2002 requires that the maximum fines content in RCA be not more than

5% by mass fraction. Previous research has shown that the fines have a detrimental effect on the

quality of concrete. Fine RCA contains many impurities and results in strength loss in the concrete

(Smith et al, 2008). Excess fines also increase the surface area for water absorption increasing the

water absorption characteristics of the mix. There was therefore need to sieve the RCA obtained by

crushing to reduce the amount of fines.

Fig 4.1- Natural Fine Aggregate, sieve analysis

0

20

40

60

80

100

120

0.1 1 10

C u m m u l a t i v e %

P a s s i n g

Log of Sieve Sizes

natural fine aggregate grading

upper limit

lower limit


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17

Fig 4.2 Recycled concrete aggregate, sieve analysis

4.2 Specific Gravity and Water Absorption

Table 4.1 - Results of Specific Gravity & Water Absorption Tests on Aggregates

Specific Gravity (AbsoluteDry) g/cm3

Water Absorption (% of drymass)

Recycled concrete aggregate 2.23 5.92

Natural fine aggregate 2.67 0.48

From Table 4.1 above, we can deduce that RCA’s water absorption is almost three times higher

than that for natural coarse aggregate, (1.99, Karara P, 2009 ). This can be attributed to the mortar

attached to the original Natural Coarse Aggregate when concrete is crushed to produce recycled

aggregates. This observation justifies the sprinkling with water of RCA before casting to achieve

SSD conditions. This pretreatment is necessary to maintain the mix design water in the mix;

otherwise this would be absorbed by the RCA resulting in a stiffer and unworkable mix.

0

20

40

60

80

100

120

1 10 100

C u m m u l a t i v e %

p a s s i n g

Log of Sieve Sizes

upper limit

lower limit

RCA grading


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18

4.3 Slump Test

Table 4.2 - Slump Test Results

The graph below (Fig 4.1) indicates that there was a reduction in slump with increase in the

amount of fibre reinforcement. This was due to absorption by the attached mortar on the RCA

which looses moisture relatively fast following saturation and surface drying, and absorption by

the fibre.

Fig 4.3-slump versus sisal fibre content

0

5

10

15

20

25

30

0% 0.20% 0.50% 1%

s l u m p ( m m )

fibre content

Workability

Sisal fibre content 0.00% 0.20% 0.50% 1.00%

Slump(mm) 27.3 25.7 18.9 13.3


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19

4.4 Compressive Strength

Table 4.3 - Compressive Strength Results

Curing age (days)

Sisal fibrecontent

7 28

0.00% 14.2 21.5

0.02% 14.9 22.4

0.50% 15.2 22.9

1.00% 14.4 21.6

The graph below graphs (fig4.2&4.3) shows that compressive strength increased gradually with

increase in the fibre reinforcement up to 0.5%, then declines. The decline is attributed to the fact

that the composite started to form balls thus proper mixing could not be attained. The control mix

achieved compressive strength of 14.2N/mm2 and 21.5N/mm2 on the seventh and twenty eighth

days respectively, compared to 15.2N/mm2 and 22.9N/mm2 for the 0.5% fibre reinforcement.

Fig 4.2-7 days compressive strength

13.6

13.8

14

14.2

14.4

14.6

14.8

15

15.2

15.4

0.00% 0.02% 0.50% 1.00%

s t r e n g t h ( N / m m 2 )

fibre content


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20

Fig 4.3-28 days compressive strength

4.4.1 Strength Development

From the graph below, it seems that the trend for strength development is roughly the same for all

the mixes. The control mix achieved 66.04% of its 28 day strength at 7 days. The 0.2%, 0.5% and

1% mixes achieved 67.34%, 65.99%, and 63.82% respectively. It was noted that 0.2%

reinforcement achieved the highest strength at 7 days.

20.5

21

21.5

22

22.5

23

23.5

0.00% 0.02% 0.50% 1.00%

s t r e n g t h ( N / m m 2 )

fibre content


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21

Fig 4.4- Strength development

4.5 Density of Concrete

Table 4.4 - measured density of concrete

Measured Density (kg/m3)

Curing (age) Sisal fibrecontent

7 28

0% 2450.37 2507.85

0.2% 2376.30 2419.85

0.5% 2311.11 2377.93

1.0% 2254.81 2323.41

As can be seen in fig 4.5 below, comparison of the densities of the concrete mixes at 28 days

showed a decreasing trend as the fibre reinforcement is increased. This is due to the comparatively

0%

20%

40%

60%

80%

100%

120%

0% 0.20% 0.50% 1%

7 day strength

28 day strength


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22

low density of the sisal fibre, and the fact that it swells upon water absorption during the curing

time. The densities achieved were 2507.85 kg/m3, 2419.85/m3, 2377.93/m3, and 2323.41kg/m3 for

0%, 0.2%, 0.5%, and 1% fibre reinforcement respectively.

Fig 4.5- Measured densities at 28 days

4.6 Flexural Strength

During the flexural strength test, all the specimens failed within the middle third of the beam. The

flexural strength of the specimen was thus computed using the formula;

=

Where:

R = modulus of rupture, kPa

P = maximum applied load indicated by the testing machine, N

l = span length, mm

b = average width of specimen (mm)

d = average depth of specimen (mm)

2200

2250

2300

2350

2400

2450

2500

2550

0% 0.20% 0.50% 1.00%

D e

n s i t y ( k g / m 3 )

fibre content


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23

The values obtained are as tabulated below:

Table 4.5 - Flexural strength at 28 days

Below is a graphical representation of the flexural strengths for the various mixes that were tested

at 28 days (Fig 4.6). It shows that flexural strength increased gradually with increase in the fibre

reinforcement up to 0.5%, then declines. The decline is attributed to the fact that the composite

started to form balls thus proper mixing could not be attained. The control mix achieved flexural

strength of 3.55N/mm2 while 0.5% and 1.0% reinforcements attained 3.703N/mm2 and

3.653N/mm2 respectively.

Fig 4.6- Flexural strength at 28 days

3.45

3.5

3.55

3.6

3.65

3.7

3.75

0% 0.50% 1.00%

f l e x

u r a l s t r e n g t h ( N / m m 2 )

fibre content

Sisal fibre content 0% 0.5% 1.0%Flexural strength(KPa)

3.55 3.70 3.65


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Fig 4.7 Beam flexure Testing


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25

CHAPTER 5

5.0 CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

This study provides evidence that supports the following conclusions.

1. The strength properties of concrete mix containing recycled concrete aggregate as the

course aggregate can be successfully improved by using sisal fibre reinforcement.

2.

Among the mixes prepared, 0.5% sisal fibre reinforcement had the highest strength.

3. Workability of the concrete reduces as the length of the fibre and percentage fibre

reinforcement increases.

4.

Higher strength can be achieved using suitable mixing and casting techniques with

optimum fibre volume fraction and critical length.

5.2 Recommendations

1. This research only concentrated on a single production technology, thus combining fibres

with matrix in a pan mixer as if the fibres were an extra gradient in the common method of

producing cementitious mix. Investigation into other production technologies is

recommended.

2. The research also concentrated on the effect of fibre reinforcement in a class 20 concrete

mix. Other mix designs should be investigated.

3. Investigations into durability performance of sisal fibre reinforced cement based

composites is recommended to counter possible fibre mineralisation by calcium hydroxide.


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REFERENCES

Amorel, and J.L. Gallias 1994, Practical Guidelines for the Reuse of Recycled Aggregates in

Concrete in France and Spain.

Bs 8500-1 2002 Concrete Made with Recycled Materials for Sustainable Concrete Construction.

Bentur, A.; Mindess, S.1990, Fibre reinforced cementitious composites, Elsevier Applied Science,

U.K.

Cappelen, P. 1978, Roof sheets made of sisal reinforced concrete. Building Research Unit,

Ministry of Lands Housing and Urban Development. Working Report , WR 14, p. 1-7.

England, G.L.; Tolêdo Filho, R.D. 1997, Natural fibre reinforced concrete. In: Asia-Pacific

specialty conference on fibre reinforced concrete, Singapore.

Ghavami, K.; Tolêdo Filho, R.D. Mechanical properties of composites reinforced with sisal fibre.

First international conference on composite engineering , New Orleans, August, p. 721-722, 1994.

Gram, H.E. 1983, Durability of natural fibres in concrete. Swedish Cement and Concrete Research

Institute.

Guimarães, S. S. Experimental mixing and moulding with vegetable fibre reinforced cement

composites.

J.D Merelet and P. Pimienta 1994, Mechanical and Physiochemical Propeties of Concrete

produced with Coarse and Fine Recycled Concrete Aggregates.

James T. Smith and Susan L. Tighe 2008, Coarse Recycled Aggregate Concrete Pavements –

Design, Instrumentation, and Performance.

Joseph, K.;Toledo Filho, R. D.; James, B.; Thomas, S.; Carvalho, L.H. 1999, The use of sisal fibre

as reinforcements in polymer in composites, Brazilian Journal of Agricultural and Environmental

Engineering.

M. Kikuchi and Y. Yasunaga 1994,The Total Evaluation of Recycled Aggregate and Recycled

Concrete.

Mehta, P. Kumar. 2001, Reducing the Environmental Impact of Concrete.

Naik, Tarun R., and Moriconi, G. 2005, Environmental-Friendly Durable.

National Ready Mix Concrete Association, CIP 16, 2000.

P.J. Wainwright, A Trevorrow, Y.Yu and Y.Wang 1994, Modifying the Performance of Concrete

made with Coarse and Fine Recycled Concrete Aggregate.

Romauldi, J.P.; Batson, G.B. 1963, Mechanics of crack arrest in concrete. Journal of the

Engineering Mechanics Division, Proceedings of the ASCE, v. 89.

S.U. Al-Dulaijan, M. Maslehuddin, M.M. Al-Zahrani, A.M. Sharif, S.H. Alidi, and M.H. Al-

Mehthel 2002, Effect of Aggregate Quality on the Properties of Concrete.


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27

Swift, D.G.; Smith, R.S.L. 1978, Sisal fibre reinforcement of cement paste and concrete. In:

Materials of construction for developing countries. Bangkok.

Tarr, Scott M., and Farny, James A. 2008, Concrete Floors on Ground .

Tolêdo Filho, R.D. 1997, Natural fibre reinforced mortar composites: Experimental

characterisation, Rio de Janeiro: Ph.D. Thesis.

US Department of Transportation 2004, Transportation Applications of Recycled Concrete

Aggregate.

Winston F.K. Fong, Jaime S.K. Yeung, and C.S. Poon 2003, Hong Kong , Experience of Using

Recycled Aggregates from Construction and Demolition Materials in Ready Mix Concrete.


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APPENDIX APPENDIX A -SIEVE ANALYSIS

Natural Fine aggregate & Recycled Coarse Aggregate Sieve Analysis Results

Table 5.1 Fine Aggregate Sieve Analysis

Table 5.2 Recycled Course Aggregate Sieve Analysis

Sieve sizemm

Wt retainedg

Wt passingg

% retained Cumulative%retained

Cumulative% passing

40 0 2823 0 0 100

30 0 2823 0 0 100

20 841 1982 29.7 29.7 70.3

15 366 1616 12.9 42.6 57.4

10 1062.5 553.5 37.7 80.3 19.7

5 503.5 50 17.8 98.1 1.9

2.36 40 10 1.55 99.65 0.35


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APPENDIX B - SPECIFIC GRAVITY & WATER ABSORPTION, FINE AGGREGATE

Table 5.3 - Specific Gravity & Water Absorption, fine aggregates

SPECIFIC GRAVITY & WATER ABSORPTION

NATURAL FINE AGGREGATE

Weight of jar + sample +water (A)

A B Average

Weight of jar +water (B)

1706 1734.5 1720.25

Weight of saturated surfacedry sample ( C )

1417 1417 1417

Weight of oven driedsample (D)

460 505.5 482.75

Specific Gravity on an ovendried basis =

475.5 503.5 489.5

Specific Gravity on asaturated and surface dry basis =

2.68 2.68 2.68

Apparent specific gravity

2.69 2.69 2.69

Water absorption (% of drymass) =

2.71 2.71 2.71

0.55 0.4 0.48


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30

APPENDIX C – SPECIFIC GRAVITY & WATER ABSORPTION, RCA

Table 5.4 - Specific Gravity & Water Absorption, RCA

SPECIFIC GRAVITY & WATER ABSORPTION TEST

RECYCLED CONCRETE AGGREGATE

A B Average

Weight of wire Basket (g)A

398 398 398

Weight of wire Basket +aggregate, B

1698 1755 1726.5

Weight of Aggregate inwater Ww = A+B

1300 1357 1328.5

Weight of saturated surface

dry sample (Ws)

2269.5 2319.5 2294.5

Weight of oven driedsample (Wd)

2135.5 2182 2158.75

Specific Gravity onsaturated surface dry basis =

2.34 2.41 2.38

Absolute Specific gravity

2.20 2.27 2.24

Water Absoprtion (% of dryweight)

5.9 5.93 5.92


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APPENDIX D – MIX DESIGN

Table 5.5 - Concrete Mix Design

Reference Calculations

Unrestricted Design

Slump required 15-30

Maximum aggregate size 20mm

Maximum free water/cement ratio 0.55

Minimum cement content 290Kg/m3

Compressive strength 20N/mm2

@ 28 days

Stage 1

BS 5328 k (5% defective) = 1.64

Fig 3 s = 8N/mm2

C1 M =ks 13.12

C2 f m =f c+M 33N/mm2

Table 2 Strength of mix with free w/c ratio of 0.5

Cement OPC

Aggregate type crushed

Age 28 days

Strength 49N/mm2

Fig 4 Max free w/c ratio 0.48

Adopt the max w/c ratio of 0.48


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32

Reference Calculations

Stage 2

Table 3 Free water content

Max aggregate size 20mm

Aggregate type crushed

Slump 15-30

Approximate free water content 190kg/m3

Stage 3

C3 Cement content =

395.83Kg/m3

Stage 4

Total aggregate content

Relative density of combined aggregate

on SSD (assumed for crushed) 2.7

fig 5 Density of concrete 2430Kg/m3

C4 Total aggregate content =D-C-W 1844.17Kg/m3

D= density of wet concrete

C= cement content

W= free water content

Stage 5

Fine and course aggregate content

Fig 6 Grading curve (fine agg.)- second graph, aggregate size 20mm

Proportion of fine aggregate 32%

C5 Fine aggregate required 590.13Kg/m2

Course aggregate(RCA)= total agg – fine agg 1254.04Kg/m2


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33

APPENDIX E – MIXING PROPORTIONS

Table 5.6 - Mix proportions, 0% sisal fibre

Quantities Cement (Kg) Water (Kg) Fine aggregate

(Kg)

Course

aggregate (Kg)RCA

Sisal fibre

(Kg)

Per m 395.83 190 590.13 1254.04 0.00

Table 5.7 - Mix proportions, 0.2% sisal fibre

Quantities Cement (Kg) Water (Kg) Fine aggregate(Kg)

Courseaggregate (Kg)RCA

Sisal fibre(Kg)

Per m 395.83 190 590.13 1254.04 4.86

Table 5.8 - Mix proportions, 0.5% sisal fibre



Sisal fibre(Kg)

Per m 395.83 190 590.13 1254.04 12.15

Table 5.9 - Mix proportions, 1% sisal fibre



Sisal fibre(Kg)

Per m 395.83 190 590.13 1254.04 24.30


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APPENDIX G – FLEXURE TEST RESULTS

Table 5.11 - Raw flexural Strength results

ast ng

date

est ng

date

ge sa re

content

a e s ea ng

(tonnes)

mo u us o

rupture

verage

flexural

strength (Kpa)

4.10.10 1.11.10 28 0% B0-8-1B0-8-2B0-8-3

0.72.72.9

0.93.43.7

3.55

4.10.10 1.11.10 28 0.5% B5-8-1B5-8-2B5-8-3

3.11.12.8

3.91.43.5

3.70

4.10.10 1.11.10 28 1% B10-8-1B10-8-2B10-8-3

2.82.91.0

3.53.81.2

3.65

Support span=425mm

APPENDIX F COMPRESSIVE STRENGTH TEST RESULTS

Table 5.10 - Raw compressive Strength results

as ng

date

ump

(mm)

es ng

date

sa re

content age

(days)

labels

u e mens on mm

length width height

o ume

(m3)

e g

(Kg)

ens y

(Kg/m3)

ea ng

(tonnes)

reng

(N/mm2)

verage

Density

verage

strength

4.10.10 27.3 4.10.10 0% 7

S0-7-1S0-7-2 S0-7-3

151150149

150150150

149150151

0.0030.0030.003

8.218.308.40

2432.62459.32488.9

25.331.432.5

11.2413.9614.44

2450.4 14.2

4.10.10 22.7 4.10.10 0.2% 7

S2-7-1 S2-7-2 S2-7-3

152150150

148150151

150150149

0.0030.0030.003

8.068.008.00

2388.12370.42370.4

32.934.220.6

14.6215.209.19

2376.3 14.9

4.10.10 18.9 4.10.10 0.5% 7

S5-7-1 S5-7-2S5-7-3

150148150

150150152

150152148

0.0030.0030.003

7.408.008.00

2192.62370.42370.4

34.134.425.9

15.1615.2911.51

2311.1 15.2

4.10.10 13.3 4.10.10 1% 7

S10-7-1 S10-7-2

S10-7-3

150150

152

150150

148

150150

150

0.0030.003

0.003

7.617.61

7.61

2354.82354.8

2354.8

26.831.8

33.0

19.9114.13

14.67

2354.8 14.4

4.10.10 27.3 1.11.10 0% 28

S0-7-1 S0-8-2 S0-8-3

150151151

150150149

150149150

0.0030.0030.003

8.468.468.46

2507.92507.72508.1

51.338.545.0

22.8017.0920.02

2507.9 21.5

4.10.10 22.7 1.11.10 0.2% 28

S2-8-1 S2-8-2 S2-8-3

150150148

151150150

149150148

0.0030.0030.003

8.178.168.17

2421.92418.12419.7

38.052.448.4

16.9023.3021.50

2419.9 22.4

4.10.10 18.9 1.11.10 0.5% 28

S5-8-1 S5-8-2 S5-8-3

152151151

148148150

150151149

0.0030.0030.003

8.008.038.06

2369.12377.92386.7

33.751.551.5

14.9922.9022.90

2377.9 22.9

4.10.10 13.3 1.11.10 1% 28

S10-8-1 S10-8-2 S10-8-3

150149152

150150148

150151150

0.0030.0030.003

7.847.847.84

2322.22324.42323.6

46.850.249.0

20.8022.3021.78

2323.4 21.6

Moses-final Project Report

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