The document discusses prefabricated concrete structures. It begins with an abstract that defines prefabrication as assembling components in a factory that are then transported to the construction site. It notes precast concrete comes in various shapes and sizes. The document then covers types of precast elements like walls, columns, and slabs. It discusses the production process for these elements and advantages like reduced cost and time. Finally, it provides examples of precast concrete implementation in large infrastructure projects in Karnataka, India.

1. Presented By,
ABHISHEKA T 1VI15CV002
UNDER THE GUIDANCE OF
Mr G A SATISH
ASSISTANT PROFESSOR
PREFABRICATED STRUCTURES
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2. CONTENTS:
• Abstract
• Introduction
• Literature Survey
• Types of precast concrete elements
• Implementation
• Conclusion
• References
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3. ABSTRACT:
 Prefabrication is a industry term used to relate assemblies that are fabricated under processing factory
conditions and transported to the construction site.
 Precast concrete is available in many shape, sizes, including structural elements and unreinforced elements.
 The prefab industry is the backbone for the development of new ideas in construction business of any country.
Factory buildings, residential buildings and the industrial township are needed practically by all the sectors,
either to support the manufacturing or services of any industry.
 The goal of prefabrication systems is to offer a way to get a well-designed building that is at least roughly
fitted to resident’s needs.
 It could be stated that prefabrication systems in building construction have the most effect on time and cost
reduction.
 Prefabrication is preferred with special emphasis on the building components made off-site in a factory.
 Off-site fabrication is a topic of international interest and provides an effective construction technique in
terms of quality, time, cost, function, productivity and safety.
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4. INTRODUCTION:
 Prefabricated structure the component member is precast, either in factories or in temporary plants established
on the site. These precast members are transported to the site, raised and set into complete structure. This
process is called as Prefabricated Construction.
 It is essential to have more residential buildings with lesser cost and lesser time in this modem culture, and
fast growing population. One such way is to use prefabrication techniques to reduce the overall cost and to
greatly reduce the construction time of buildings, prefabricated units are adopted.
 There are various technologies available worldwide for using prefabricated construction methods, almost all
technologies try to reduce costs and time, prefabrication method gives possibility to the designers for
assembling their structures in a short period of time.
 Although designers are allowed to use different kinds of materials, they mostly prefer to choose light weight
ones. Wood and steel are the most practical materials in prefabrication construction.
 Prefabrication process is the association and administration of the arrangements, materials and work included
in the construction of buildings or components. Nowadays prefabrication technologies play an important role
in multiple developing countries and its usage has been increasing every day.
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5. Fig: Installing of Roof Truss Fig: Raised Prefabricated Building Fig: Modular Prefabricated Building
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6. LITERATURE SURVEY:
1. Study on Prefabrication system by Monika Shekhar Gupta :
The focus of this paper is to study the various methods that are used today when constructing prefabricated
buildings. The aim of this research is to examine various prefabrication systems according to their structural
elements.
In this system, in place of traditional RCC framed construction of columns and beams; all walls, floors, slabs,
columns, beams, stairs, together with door and window openings are cast-in-place monolithically using
appropriate grade of concrete in one operation.
The specially custom designed modular formwork made up of Aluminium /Plastic/ Aluminium-Plastic
Composite is easy to handle with minimum labour & without use of any equipment. Being modular formwork
system, Therefore, the future of prefabrication can be seen as the improvement of the current market and the
new development pattern market. It facilitates in rapid construction of multiple/mass unit scale.
The complete construction of prefabricated building can be done within one-fourth of the time that is required
for conventional construction.
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7. 2. Implementation of Precast Technology in India by VPS Nihar Nanyama, Riddha Basua, Anil Sawhney :
Precast construction is a stage wise process consisting of producing elements in a factory set environment,
transporting these elements to the site, erecting them at the site and assembling them.
Precast is a preferred method and has flexibility in planning and production process until the precast components
are delivered as per the schedule. Numerous benefits are associated with adoption of precast on a construction
site when compared to conventional systems.
Main advantages of precast construction are: reduction in time, reduction of wastage in materials, the lesser
requirement of labor at the site, improved quality of the product, enhanced safety at the site, etc.
These benefits can help the project in delivering effectively and efficiently. Primarily, this research focusses on
identifying the opportunities and challenges associated with the implementation of precast technology in India.
To achieve the goal set for the research, the following objectives were formulated. To present a cost model for
precast technology in comparison with conventional methods of construction for a building project. To analyze
time and cost for precast projects in comparison with conventional method of construction.
To determine the major challenges that are faced by precast technology at a project site and industry level .To
provide amicable solutions to the challenges faced by precast technology.
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8. 3. Using Prefabrication systems in Building Construction by Meltem Vatan Kaptan and Omid Reza
Baghchesaraei:
The work with this article was initiated with a general literature study to get an overview of construction
methodologies of prefabrication systems to acquire some background knowledge of these kinds of constructions.
There were two categories for this research:
a. Empirical studies: To investigate appropriate prefabrication systems used for building construction.
b. Prefabrication systems assembling behavior: recognizing relationship between prefabrication systems and its
assembling process.
Utilizing the measured framework can spare a great deal of time and money. The measured unit is commonly
manufactured or composed utilizing a standardization framework and measurement which makes it simple to
mass produce.
Therefore, prefabrication systems are divided in three different types in terms of structural configuration Frame
systems, Panel systems , Cells system. Innovation exchange of construction procedure, including materials and
advanced instruments, can influence nature, economy and society of the accepting nation contrarily.
Prefabrication systems might have some potential of increased use in future because of their characteristics.
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9. Summary of Literature:
From the above literature papers we can summarize that prefabricated structures can be used as an alternative to the ordinary
bricks masonry or normal construction process of structures which consumes very less materials and is more resistant to
withstand the loads.
The use of prefabrication and preassembly is estimated to have almost doubled in the last 15 years, increasing by 86%. The use
of precast concrete construction can significantly reduce the amount of construction waste generated on construction sites.
Reduce adverse environmental impact on sites. Enhance quality control of concreting work. Reduce the amount of site labour.
Increase worker safety. Other advantages by using Prefabricated structures in this papers are prefabricated structures increases
possibility of conversion, disassembling and moving to another site, Possibility of erection in areas where a traditional
construction practice is not possible or difficult, low labor intensivity. It can also reduce wastage of materials and Easier
management of construction sites. Better overall construction quality.
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10. TYPES OF PRECAST CONCRETE ELEMENTS:
1.PRECAST WALLS:
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Precast Concrete walls making process:
Precast concrete walls are made in a controlled plant environment where weather doesn’t interfere with the
curing process. Precast walls production starts with a mix of crushed rock and sand. This mix is limestone based.
The conveyor delivers the minerals in a huge mixer. They inject cement, water and additives to improve the
flow of concrete.
Some amount of concrete is been casted into cylindrical shapes for testing. After one day cure, they crush the
cylinders with a ram. The amount of force it takes to crush the cylinders is a measure of the concrete’s batch
strength.
Before the wall is casted, if something has to be imprinted in the mould, the letters are positioned to the center
of casting form and it is secured with silicone. A release agent is sprayed onto the casting form and letters.
Fig: Batching carried out for required proportion

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Fig: Spraying release agent on letters
 High strength steel cables are strung throughout the form with a hydraulic device, they pull each cable
to a specific tension.
 The rebar rod is bent into a loop, the rebar loops are linked, creating long cages. One cage is placed at
the top of the form and the other at the bottom, later on sheet of welded wire mesh according to the
required size of the form.
 A truck distribute the concrete directly into the form. The concrete flows around the steel reinforcement.
The steel will keep the wall strong when the concrete expands and contracts as the weather changes. The
concrete is spreaded and is levelled with a tool called “Screed”.
Fig: Rebar's placing in to the form

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Fig: Concrete pour
 This first layer of wall panel is essentially one side of a sandwich. It will be the exterior part of the wall.
At the center of the sandwich rigid form insulation is provided, its studded with projection to secure it to
the concrete .More steel reinforced completes the sandwich. This final layer will face the inside of
building, care is taken to ensure that there are no pits.
Fig: Rigid foam Insulation
 After about 12hours,the wall is solid enough to be handled. The small section of the exterior side is
blasted to remove the surface cement to expose the aggregate ,creating a decorative band next to mould
lettering.
 After a 3day cure, the precast concrete wall is ready for erection in the construction site . Later on it is
placed on Footings and the design is aligned to the one on next wall when the 2 walls match up perfectly
they are bolted down.
 The concrete is cured over time , so the precast walls will stand strong for many years.
Fig: Assemblage of walls with nuts

13. 2.PRECAST COLUMNS:
PRECAST CONCRETE COLUMNS MAKING PROCESS:
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 First step is preparation of mould, later the entire moulds are greased or oiled.
 After the surface preparation the pretensioned cables are stretched so that they can withstand enough stresses.
 The reinforcements are provided and the concrete is poured into the mould and It is provided with enough
vibration.
 After 24 hours casted columns are demoulded.
Fig: prepared mould Rebars placing pouring of concrete Demoulding Precast column

14. 3.PRECAST SLAB:
PRECAST CONCRETE SLAB MAKING PROCESS:
 The architectural drawings are used by structural engineers to design the special customized slabs. Pre-
stressed slabs are casted on beds. Strands are being pulled & stressed through stressing machine. Concrete is
then transferred to the concrete distributor machine from bucket.
 Casting is being carried in two layers namely bottom layer and top layer. Vertical cutouts are being made on
fresh concrete and horizontal cutouts after the concrete is hardened. Once the elements are cured, slabs are cut
into pieces of required size, they are lifted and sent to stockyard. slabs are transported to the site in special
transportation racks that are lifted and placed onto the trucks.
 The stiffeners in the precast slabs serve directly as a support for the top bars. Possibility of making more
openings and making elements for the ends of bays and particular shapes.The precast slab is perfect for
housing, office buildings, shops, schools, hospitals, car parks, sports complexes, etc
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Fig:Rebars placed Fig: Concrete pouring Fig: Precast Slabs

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Curing : After 24 hours of casting, the casted components are released from the mould and transported to
curing tanks. Steam curing process is used in the fabrication of precast, prestressed members in plants to
improve production efficiency and quality control and to attain a sufficient concrete compressive strength to
transfer the prestress within the turnover period.
Steam curing :
This method is useful in cold weather. There are two methods of curing:
1.Steam at atmospheric pressure: (or low pressure):
This is used for enclosed cast-in-place structures and large precast units. In the precast concrete industry,
steam curing allows increased production by a more rapid turnover of molds and formwork. The higher the
initial temperature of the curing environment, the lower the ultimate strength. This means that the
temperature used will be a compromise between the rate of strength gain and the ultimate strength.

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2.High pressure steam:
This method is used for small manufactured units. The curing is done in autoclaves. Precast elements are placed
in closed chamber and high pressure, high temperature is supplied. the advantage of high pressure steam cure is
the concrete can cured in one day less obtained 28 days strength of normal concrete .It exhibits to high
resistance to sulphate attack, freezing and thawing action, chemical action, lower drying shrinkage and moisture
movement.

17. ADVANTAGES OF PREFABRICATED CONSTRUCTION:
 Prefabricated structures save the time, cost and materials.
 In this structures shuttering and scaffolding is not necessary.
 The installation of building services and finishes can be done immediately.
 Less man power is needed because the precast units are manufactured in a factory.
 Better quality of the products is obtained as a result of manufacture under factory conditions with constant
Quality control, the use of machines, and the better working environment provided by the factory.
 Units can be manufactured in covered buildings which can be heated and erection of the units can also be
carried out in winter and construction can proceed almost independently of weather conditions.
DISADVANTAGES OF PREFABRICATED CONSTRUCTION:
 The transportation cost is high.
 Handling and transportation may cause breakages of members.
 Difficult to connect the precast units.
 Precast members are to be placed in position, otherwise loads coming on them are likely to get changed and
members may be affected.
 Erection equipment is needed.
 Skilled labour and supervision is required
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18. IMPLEMENTATION:
The major implementations in the field of Prefabrication in Karnataka so far includes major projects like:
1.Namma Metro Project.
2.Indira Canteen.
1.Namma Metro :
Bangalore metro is second longest operational metro network in India after the Delhi Metro. On the other
hand, Bangalore Metro was ranked the 83rd largest metro system in terms of length and the 79th largest metro
network in terms of number of operating stations in the world. It also contains the first underground metro line
in South India.
Fig: precast segmental box girder. fig: box girder segmental construction.
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19. 2.Indira Canteen:
Indira Canteen Mainly used the Prefabricated elements to cast and erect the structure. Here the structural
Elements such as Beams, Slabs, Walls were casted offsite and was bought to the site for assemblage.
Assemblage of Beam Assemblage of Slab
Assemblage of Walls Assemblage of Slab
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20. 3.PRECAST CONCRETE TOILETS:
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restrooms are a permanent and economical solution for parks & recreation facilities, schools,
transportation facilities, military bases and secured installations.

21. Conclusion:
• Prefabrication will keep on growing in many different countries as the interest for quick reasonable building
increments.
• Innovation exchange of construction procedure, including materials and advanced instruments, can influence
nature, economy and society of the accepting nation contrarily.
• Therefore, the future of prefabrication can be seen as the improvement of the current market and the new
development pattern market.
• Today, prefabrication is not just being seen as a development strategy for moderate activities however it has
additionally ventured into the extravagance market.
• Creating top notch building parts from a processing factory will exceptionally basic in near future. Since the
innovations of large scale manufacturing for customer items will grow quick, these advances can help build
the nature of building components to a higher standard.
• Prefabrication systems might have some potential of increased use in future because of their characteristics.
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22. References:
 Study on Prefabrication system by Monika Shekhar Gupta :
 Implementation of Precast Technology in India by VPS Nihar Nanyama, Riddha Basua, Anil Sawhney :
 Using Prefabrication systems in Building Construction by Meltem Vatan Kaptan and Omid Reza
Baghchesaraei
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23. THANK YOU
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