Prefabrication and its Adoption in India

Prefabrication and its Adoption in India
Rachit Sharma, Kshitij Mudgal , Monil Shrivastava, Mohanish Gupta
- Undergraduate students at Department of Civil Engineering,
Jaypee University Of Engineering And Technology
Abstract
With the rapidly increasing population in our country, the housing problem today has assumed the
gigantic proportions. The traditional method of building construction can't deliver the goods, until we
bring a revolution in the construction field, which needs to be more massive than the Green
Revolution. This can be done by adopting prefabricated system. It should solve these problems to a
great extent by achieving speed in construction and economic use of building materials. This would
also reduce the waste generated at the construction site. The success of this prefab system would
require the government involvement in housing. This can be done by establishing building factories
located in various parts of the whole country. There should be a government policy of housing which
would strongly affect the building industry. The users needs to be educated too by ways of
advertisements, workshops etc. Here, we are discussing the prefabrication techniques and the material
classifications used in construction with some fascinating case studies.
Introduction
It would be so significant when a low cost house could stand tall within two days! Yes, this is the
current advancement in the construction technology and this great technique called Prefabrication has
emerged in the world at a rapid rate, leaving behind a large nation, India, which is still undergoing
construction in the conventional manner. Though some efforts have been made in this field in India
but they aren't in an organized manner . Bricks, concrete mortar, reinforced cement concrete, tiles are
the still same present scenario in India, which is all time consuming and very expensive. The need is
to shift our gears towards the prefabrication and pre-cast techniques which emphasis upon the reduced
time delay in construction and the increased productivity. Prefabrication would only affect the process
of construction and not the end-product. So, it is an alternative pathway towards contriving a building
and only affects the construction process.
Prefabrication, being of utmost necessity to a country like India, will offer opportunities for dealing
with the shortage of skilled labour and the declining workmanship standards. Site construction work is
National Conference on Alternative & Innovative Construction Materials & Techniques| 27-Sep-14 2
traditionally vulnerable to weather disruptions. By using prefabrication the site will be vulnerable for
lesser time and so the risk of delay and requirements for protection will be reduced. The quality of
construction is much higher when components are manufactured in a stable environment.
Classification [3]
`
`
LARGE BLOCK MEDIUM PANEL CONSTRUCTION LARGE PANEL CONSTRUCTION BOX UNIT
CONSTRUCTION CONSTRUCTION
(a.)Light Prefabrication:
1). Large block construction-
The elements of this type are large enough to make pace in construction, but at the same time
are small enough to be handled with ease. Size of the blocks , in general, does not exceed one
square meter. They can be used in walls and floors.
2). Medium panel construction- These elements may stretch from floor to floor and wall to
wall. These are bigger in size having less number of joints. The width is one meter or lesser
than this.
(b.)Heavy Prefabrication:
1). Large panel construction-
They are heavier and bigger and cover the whole wall or roof of a room. Joints are
eliminated within the room except at corner. Here heavy mechanization is needed,
considering the large size of the panels.
2). Box unit construction-
There is a box like element in this construction which fully encloses a space in the form of a
room like bedroom, drawing room, kitchen, toilet in complete. There is a need for welding of
PREFABRICATION
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boxes maybe side by side, one over the other or may be kept apart. Heavy mechanization is
required.
Materials
The prefabricated materials used in construction are majorly described as-
(1). Structural Insulated Panels(SIPs)
They are a composite building material consisting of an insulated layer of rigid core
sandwiched between two layers of structural board. This board can be of cement, plywood,
sheet metal etc. SIPs share the same structural properties as an I-beam or I-column. They can
be used for many different applications, such as exterior wall, roof, floor and foundation
systems.
(2).Insulating concrete forms(IRFs)
It is a system of formwork for reinforced concrete(RCC) made with a rigid thermal
insulation that stays in place as a permanent interior and exterior substrate for walls, floors,
and roofs. The forms are interlocking modular units that are dry-stacked (without mortar) and
filled with concrete.
(3). Prefab Foundation System
A prefabricated foundation is provided using concrete panels that are cast at a factory
location to a predetermined uniform form and size. These panels are of a general rectangular
shape and are positioned end to end forming a wall-like structure around the entire perimeter
of a prefabricated structure. The upper edge of the precast panels are locked in position
keeping them from moving in either an inward or outward manner thereby providing a stable
platform upon which a prefabricated structure can be placed.
(4). Steel Framing
Steel frame usually refers to a building technique with a skeleton frame of
vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the
floors, roof and walls of a building which are all attached to the frame.
(5).Precast Concrete
It is a construction product produced by casting concrete in a reusable mould or "form" which
is then cured in a controlled environment, transported to the construction site and lifted into
place.
Case Study
1. Dynamic Tower, Dubai [8]
It will be the world's first prefabricated skyscraper with 40 factory-built modules for each
floor.The 420-metre building's apartments would spin a full 360 degrees, at voice command,
around a central column by means of power-generating wind turbines.
90% of the tower will be built in a factory and shipped to the construction site. It will take
the entire building to complete in 22 months. The core of the tower will be built at the
construction site. Part of this prefabrication will lead to a decrease in the cost and number of
workers . The total construction time will be over 30% less than a normal skyscraper of the
same size. The traditional building and the dynamic architecture requires 2000 and 90
workers respectively. The majority of the workers will be in factories, where it will be much
safer. The modules will be preinstalled including kitchen and bathroom fixtures. The core
will serve each floor with a special, patented connection for clean water supply.
The entire tower will be powered from wind energy and solar energy. The turbines will be
located between each of the rotating floors. They could generate up to 1,200,000 kilowatt-
hours of energy. The solar panels will be located on the roof and the top of each floor.
2.Instacon,Mohali [9]
Being first in India, this building was completed in just 48 hours, for which the company-
Synergy Thrislington entered the Limca Book of Records for constructing this 10 storey
commercial building. With the help of three cranes and more than 200 high skilled workers,
this 48 hour masterwork stands tall in the vibrant city.
The external structure of the building comprises double-skinned PUF panel (PVDF
galvalume coated sheet) that ensures thermal insulation. The core material used for Instacon
is mild steel, which is lightweight, strong, flexible and environment-friendly.
The company made arrangements to ensure that around 80-90 per cent of the work was
completed in the factory under a controlled environment. In this system, different units of the
building such as wall panels, columns, etc, were produced within the factory and then placed
on a special vehicle that transported them to the actual site where 10-20 per cent of the work
was carried out by simply installing them. Only 10-20 per cent of the work was carried out at
the site, which reduced the amount of waste, carbon footprint and the impact on green spaces
at the actual site. The structure is also energy-efficient as it provides floor insulation using the
HVAC technique.
This great structure provides a hope that further upcoming mega structures can be built like
this brilliant technique, thus taking India to greater heights in the field of construction.
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CONCLUSION
For the success of prefabricated system, the govt. should come forward in establishing
building factories and they should be located in various places in the whole country. For
continuous flow of production a stable market must be created and govt. should fix the annual
quota for the construction of prefabricated houses for mass housing. Since the govt policy
affects the building history as it provides a large scale market both positive and attractive.
Another factor to keep in mind is there must be a proper understanding among manufacturers,
architects ,designers and builders. The architect and designers should go for standardisation
in planning and design. Also builders must be conscious about quality, strength and economy
of prefabricated components. So they must be educated by seminars, workshops,exihibition,
demonstration of prefabricated system etc.
We have to also raise the standards of teaching by enforcing this as compulsory in the subject
curriculum so that it can be implemented practically as well. Prefabrication has the capability
to make a difference within the Indian construction industry in economic, social and
environmental terms. The possibilities and opportunities are immense and what all needed is
a courageous step by entrepreneurs to make a change.
Where there is a will, there is a way!
REFERENCES
ISBN 81-7515-246-X
[6] http://projects.bre.co.uk/prefabrication/prefabrication.pdf
[7] http://www.sciencedirect.com/science/article/pii/S0360132306002873
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Scientific Journal of Impact Factor (SJIF): 4.72 e-ISSN (O): 2348-4470 p-ISSN (P): 2348-6406
Comparative Study of Prefabrication Constructions with Cast-in-Situ
Constructions
1 P.G. Student, Department of Civil Engineering, Rajarambapu Institute of Technology, Rajaramnagar,
Maharashtra,India 2 Director, Rajarambapu Institute of Technology, Rajaramnagar , Maharashtra, India
Abstract — The conventional method of concreting i.e. cast- in-situ is mostly used for various types of constructions.
There are many drawbacks of this method like less quality, lesser speed of construction, high labour requirement etc.
These drawbacks ultimately affect the structure. To overcome these drawbacks a new method of concreting can be
adopted called as precast concrete method. Precast concrete method is accepted worldwide for its advantages over
conventional concrete method. The main aim of this paper is to present a prefabricated construction based on time and cost utilization over than in-situ construction. A literature survey and field visits are carried out to predict the time and
cost behaviour. Precast construction technology is quite popular and comfortable method of construction in developed
countries attributes the several advantages. However, in India, conventional construction method is still widely accepted
despite incurring higher cost and slow production rate.
Keywords- Precast technology, mold cost, panelization, frame, prestress, transportation
I. INTRODUCTION
Prefabrication has been widely regarded as an endurable construction method in terms of its impact on the protection of
the environment. An important aspect of this perspective is the influence of prefabrication on the reduction of
construction waste and subsequent waste management activities, including classification, reuse, recycling and waste
disposal. Prefabrication is a productive construction technique in terms of time, quality, cost, productivity, safety and functionality. The construction boom in India is developing at an accelerated rate of growth. It provides ample
opportunity in India for a new entrant in the prefabricated sector. Today, prefabricated concrete buildings are the
advanced construction techniques available around the world. Due to their wide applicability, prefabricated systems for
buildings are becoming a popular choice for many constructions. Prefabricated concrete available in many shapes, sizes,
including structural elements and non-reinforced parts. The concept of prefabricated construction includes those
buildings, where most structural components are standardized and produced in factories at a location away from the
building, and then transported to the assembly site.
These components are manufactured by industrial methods i.e mass production in order to build a large number of
buildings in a short time at low cost.
The salient features of this construction process are as follows:
1. The division and specialization of the labour workforce. 2. The use of tools, machinery, and other equipment, usually automated, in the production of standard, interchangeable
parts and products.
3. Precast concrete elements’ erection is faster and less affected by adverse weather conditions.
4. Factory casting allows increasing efficiency, high quality control and greater control on finishes.
II. CAST-IN-SITU CONSTRUCTIONS
Concrete is the most essential part of the modern structure. The concrete provides compressive strength to the structure which helps the structure to withstand compressive forces. There are different methods of concreting one of which is the
conventional method of concreting denominated like cast in situ that is generally used for the construction. This is the
oldest method of concreting and used for many years in the construction industry. Cast-in-situ is the conventional method
of concreting. In this method concrete is prepared on site and poured into formwork and then cured. It often requires
more work and even takes more time. It has some limitations or drawbacks. The most important drawback of the in-situ
molding method is that the quality of the concrete cannot be assured and more time required for the construction. In
recent times when quality is more important in a minimum time, the cast-in-situ method is less advantageous. In order to
overcome the drawbacks of the concreting method in situ and to follow the terms of the modern era a new concreting
method called prefabricated concrete can be adopted.
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III. PRECAST CONCRETE STRUCTURES
3.1.1. Large-Panel Systems
The vertical and horizontal connection of large floor and wall concrete panels in a multi-storeyed buildings, such that the
panels form rooms by enclosing spaces in a box-like manner within the building, is referred to as the large-panel system.
The panels resist gravitational loads and provide flexibility in the interior layout. Wall panels are usually the height of a
single storey. The horizontal floor and roof panels span have one- or two-way slabs. With proper joints, the horizontal
panels transfer lateral loads to the walls. There are three possible configurations based on the wall layout: i. Cross-wall system: the gravity-resisting walls are placed in the short direction of the building
ii. Longitudinal-wall system: the gravity-resisting walls are longitudinally placed
iii. Two-way system: the placement of the walls is in both directions.
The advantage of large panel system is speedy construction, insulation, fire resistance and paint-ready surface finishing.
It is suitable for residential apartments and hotels.
Depending on the construction method, the joints can be classified as wet and dry. Wet joints are constructed with the
concrete poured between the precast panels. To ensure structural continuity, protruding reinforcing bars from the panels
are welded, looped, or otherwise connected in the joint region before the concrete is placed. Dry joints are constructed by bolting or welding together steel plates or other steel inserts cast into the ends of the precast panels. Wet joints more
closely approximate cast-in-place construction, whereas the force transfer in structures with dry joints is accomplished at
discrete points.
3.1.2. Frame Systems
Frame system is better suited for the buildings which require more flexibility, such as industrial buildings, multi-level car
parking, offices, shopping malls and sports facilities. Precast frames can be constructed in two ways: spatial beam-
column sub- assemblages and linear elements. The former construction allows the placement of connecting faces away from critical regions but are difficult to form, handle and assembly, and as such the use of linear elements is preferred.
The beams can be seated on corbels at the columns, for ease of construction and to help the shear transfer from the beam
to the column. The beam-column joints accomplished in this way are hinged.
3.1.3. Slab-Column Systems With Shear Walls
In this system, the slab-column structure is used to resist gravitational loads while shear walls are relied upon to sustain
the effects of lateral loads. Two sub-systems in this category are:
i)Lift-slab system with walls
Precast concrete floor slabs are lifted from the ground up to the desired height by lifting cranes. The slab panels are lifted
to the top of the column and then moved downwards to the final position. To keep the slabs in the position till the
connection with the columns has been achieved the temporary supports are been used.
In the connections, the dowel bars that project from the edges of the slabs are welded to the dowels of the adjacent
elements and transverse reinforcement bars are installed in place. Then the connections are filled by concrete that is
poured at the site. Most buildings of this type have some kind of lateral load-resisting elements, mainly consisting of precast shear walls, etc. In case lateral load-resisting elements such as shear wall are not present, the lateral load path
depends on the ability of the slab-column connections to transfer bending moments. When the connections have been
poorly constructed, it is not possible, and the lateral load path may be not completed. However, properly constructed
slab-column joints are capable of transferring moments.
ii)Prestressed slab-column system
The prestressed slab-column system uses horizontal prestressing in two orthogonal directions to achieve the continuity. The precast concrete column elements are generally one to three stories high. The reinforced concrete floor slabs fit the
clear span in between columns. After erecting the slabs and columns of a story, the columns and floor slabs are
prestressed by means of prestressing tendons that pass through the ducts in the columns at the floor level and along the
gaps left between adjacent slabs. After prestressing, the gaps between the slabs are filled with in situ concrete and the
tendons then become bonded with the spans. Seismic loads are resisted mainly by the shear walls positioned between the
columns at appropriate locations.
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3.1.4. Cell System
This system is used for specific parts of a building, such as bathroom, kitchen and stairs. The advantage of the cell
system is speedy construction and high productivity, as the fittings and finishing are carried out at the factory.
Fig.1 Typical connection of precast concrete elements
Fig.2 Slab to beam connection
3.2 Construction Process
Once the design procedure for the components is completed, each component has to undergo the following processes:
1. Concrete mixing and movement from the mixing point to the mould.
2. Setting of moulds: the moulds are cleaned and oiled and the side frames are fastened.
3. Placement of fixtures, reinforcements, electrical components and such as will form part of the components.
4. Casting: the concrete is poured, compacted and levelled.
5. Curing: naturally or artificially (by heating).
6. De-molding: the side frames are stripped and the components are taken out. 7. Finishing, patching and repairing of the components.
8. Placement of the finished components in the stockyard for delivery strength.
9. Transportation of the components to the assembly site.
3.3. Transportation & Delivery
The cost savings achieved by prefabrication are usually partially offset by transportation costs from the factory to the
project site. In addition, road transportation regulations in countries like India may also pose as a barrier to the
transportation of heavy prefabricated panels. These kinds of limitations have to be given serious consideration before the
International Journal of Advance Engineering and Research Development (IJAERD) Volume 4, Issue 3, March -2017, e-ISSN: 2348 - 4470, print-ISSN: 2348-6406
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adoption of prefabrication. It is of the essence…