by AR Mohd Bilal Ansari

1. Prefabrication
Presented to : AR Pallavi Upadhyay
Presented by : Bhanu Kumar
Nitya Prakash
Mohd. Bilal Ansari
Syed Dilkash Raza
Mohit Tyagi

2. Contents
• Introduction
• Advantages
• Disadvantages
• Components
• Materials
• Systems of Prefabrication
• Joints
• Precasting Methods
• On-site Prefabrication
• Off-site Prefabrication

3. Introduction
• The practice of assembling structural
components in a factory/other
manufacturing site and transporting
complete assemblies/sub-
assemblies to the construction site
where the structure is to be erected.
• Sections of walls, floors & roof are
prefabricated including window &
door frames.
• The elements are placed by crane
and bolted.

4. Advantages
• Prefabrication causes lesser noise
and dust.
• Offers less energy consumption
• Creates opportunities for good
architecture
• Erection can be continued even at
-20 degree Celsius
• Carries out high capacity work
• Takes less than half construction
time than the conventional cast-in-
situ concrete.

5. Advantages
• Provides complex thermal
insulation
• Improved quality over on-site
construction
• Saves time where weather
conditions allow brief periods of
construction
• It helps in safety of workers,
environmental impact,
constructability
• Do not disturb traffic during a
bridge building as much as on-site
construction.

6. Disadvantages
• Leaks in joints
• Transportation cost is high for
voluminous structures
• Large construction requires heavy
duty cranes.
• Accuracy is required in
measurement & handling to place in
position.
• Larger groups of building from same
type of prefabricated elements tend
to look monotonous.
• Need skilled labour and experience.

7. Components
• Flooring
• Roofing
• Beams
• Columns
• Walls
• Staircase
• Lintels
• Sunshade/Chajja projections

8. Materials
• Concrete
• Steel
• Treated wood
• Aluminium
• Cellular concrete
• Lightweight concrete elements
• Ceramic products

9. Systems of Prefabrication
• OPEN PREFAB SYSTEM - Open prefab system is based on use
of basic structural elements to form whole/part of a building.
• Components :
• Reinforced Concrete
• Hollow core slab
• Hollow blocks & battens
• Precast planks & battens
• Precast joists & tiles
• Cellular concrete slabs
• Presetressed/reinforeced concrete slabs, beams & columns
• Precast lintels & chajjas
• Reinforced concrete waffle slabs/shells
• Room size reinforced/prestressed concrete panels
• Reinforced concrete/ Prestressed concrete walling elements
• Reinforced concrete/presetressed concrete trusses.

10. Systems of Prefabrication
• Open prefab system is further divided
into two types :
• Partial Open Prefab
• Full Open Prefab
• PARTIAL OPEN PREFAB emphasizes the
use of precast roofing and flooring
components and minor elements like
lintels, chajjas, kitchen sills etc. It could
be in-situ framework/load bearing walls.
• FULL OPEN PREFAB includes almost all
structural components such as beams,
columns, slabs. Filler walls may be of
bricks or other material available.

11. Systems of Prefabrication
• LARGE PANEL PREFAB SYSTEM -
Large panel prefab system is
based on the use of large prefab
components as in large panels for
walls, floors, roofs, balconies,
staircase etc. Casting could be
done on site or off site.

12. Joints
• The joints should be provided in the light of
their assessment with respect to the
following considerations:
• Feasibility -The feasibility of joint shall be
determined by its loads carrying capacity in
the particular situation in which the joints is
to function.
• Practicability -Practicability of joint shall be
determined by the amount and type of
Material, fabrication and erection and the
time for fabrication and erection.
• Serviceability - Serviceability shall be
determined by the joints/expected
behaviour to Repeated or possible
overloading and exposure to climatic or
chemical conditions.
• Fire-Proofing
• Appearance

13. Joints
• JOINT TECHNIQUES/MATERIALS
NORMALLY EMPLOYED ARE:
• Welding of cleats or projecting
steel.
• Overlapping reinforcement, loops
and linking steel grouted by
concrete.
• Reinforced concrete ties all round a
slab.
• Prestressing.
• Epoxy grouting.(adhesive)
• Bolts and nuts connection.
• A combination of the above.

14. Precasting Methods
• INDIVIDUAL MOULD METHOD
• Using mould which may be easily
assembled out of bottom and
sides, transportable , if necessary
this may be either in timber or in
steel using needle or mould
vibrations and capable of taking
prestressing forces.
• Used in – Rib Slab, beams, Girders
window panels, box type units and
special elements.

15. Precasting Methods
• BATTERY FORM METHOD
• Battery form method shuttering
panels may be adjusted in the
form of a battery at the required
distances equal to the thickness of
the concrete members.
• Used in – Interior Walls ( Panels,
Shell elements, reinforced
concrete, battens, rafters ,
purlines, roof and floor slabs.

16. Precasting Methods
• STACK METHOD
• Used in – Floor and Roof slabs
panels.
• TILTING METHOD
• Used in – Mould exterior Walls.
• LONG LINE PRESTRESSING BED
METHOD
• Used in – Double tees, rib slabs,
purlines and beams.

17. EXTRUSION METHOD
• Long concrete mould with constant
cross section and vibration will be
done automatically just as in
concrete roads.
• Used in – roof slabs, concrete
walls, panels and beams.

18. In this scheme, prefabricated components are produced at site or near the site of work as
possible.
This system is normally adopted for a specific job order for a limited period. Though there is
definite economy with respect to cost of transportation, this system suffers from basic
drawback of its non-suitability to any high degree of mechanization and no elaborate
arrangements for quality control. Normal benefits of continuity of work is not available in
this system of construction. Under this category there are two types that is semi-
mechanized and fully-mechanized.
Semi-mechanized
The work is normally carried out in open space with locally available labour force. The
equipment machinery used may be minor in nature and moulds are of mobile or stationary
in nature.
On-site Prefabrication

19. • Fully-mechanized
The work carried out under shed with skilled labour.The equipments used are similar to one
of factory production. This type of precast yards will be set up for the production of precast
components of high quality, high rate of production.
On-site Prefabrication

20. Off-site Prefabrication
उर्फ़
Factory prefabrication
Factory prefabrication is resorted to in a factory for the commercial production for the
manufacture of standardized components on a long-term basis. It is a capital intensive
production where work is done throughout the year preferably under a closed shed to avoid
effects of seasonal variations. High level of mechanization can always be introduced in this
system where the work can be organized in a factory-like manner with the help of a
constant team of workmen.

21. Precast is a construction product (mostly concrete) produced by casting concrete in a
reusable mold or "form" which is then cured in a controlled environment, transported to the
construction site and lifted into place. In contrast, standard concrete is poured into site-
specific forms and cured on site.
Prefabrication is the practice of assembling components of a structure in a factory or other
manufacturing site, and transporting complete assemblies or sub-assemblies to the
construction site where the structure is to be located. The term is used to distinguish this
process from the more conventional construction practice of transporting the basic
materials to the construction site where all assembly is carried out.
PRECAST Vs(बनाम) PREFABRICATION

22. LOG ON TO WWW.GOOGLEBABA.COM OR
WWW.UTTAMRATHI.CO.IN OR IIN HAPUR.
कोई प्रश्न?
THANK YOU
धन्यवाद