Precast concrete is concrete that is cast in reusable molds or "forms" that are then cured in a controlled environment. This allows precast concrete construction to provide several benefits over traditional cast-in-place concrete including time savings, quality assurance, cost effectiveness, durability, aesthetics, and safer construction. However, precast concrete also has some disadvantages such as high initial investment costs, transportation issues, handling difficulties, limitations for modifications, and needing sensitive connection work. Overall, precast concrete can be a good solution for large construction projects where its benefits outweigh its disadvantages.

1. PRECAST
CONCRETE
BY PRASHANT BORGE

2. PRECAST CONCRETE
• Precast concrete is a construction product 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 ("tilt up"). In contrast, standard concrete is
poured into site-specific forms and cured on site.

3. ADVANTAGE
• Saves Construction Time
• Quality Assurance
• Usage of Prestressed Concrete Cost-effective
• Durability
• Aesthetics
• Safe Construction Platform

4. • Saves Construction Time: Precast Concrete construction saves time, the risk of project delay is also less.
The precast concrete casting can be carried on simultaneously with other works on site such as
earthwork, survey etc. and thus saves time.
• Quality Assurance: The key factors which regulate the quality of construction such as curing,
temperature, mix design, formwork etc. can be monitored for Precast Concrete. So, improved quality
construction can be performed.
• Usage of Prestressed Concrete: By using pre-stressed precast, structural materials of high strength and
load-bearing capacity can be achieved, which can result in greater clear span, reduced size of cross
section of structural members etc.
• Cost-effective: The simplified construction process reduces the time, increases the productivity, quality
and safety and thus the cost is reduced.
• Durability: Precast Concrete structure has longer service time period and minimal maintenance. The high-
density Precast Concrete is more durable to acid attack, corrosion, impact, reduces surface voids and
resists accumulation of dust.
• Aesthetics: As the structures are prefabricated in a controlled factory environment, several
combinations of colors and textures can be used. A wide range of shapes and sizes are available to choose
from with smooth finishing and thus the aesthetical value of products are increased.
• Safe Construction Platform: No raw materials have to be stocked in site for Precast Concrete
construction. It reduces the requirement of traditional formworks and props, wastage, workers etc. and
thus provides a safe working platform

5. DISADVANTAGE
• High Initial Investment
• Transportation Issue
• Handling Difficulties
• Modification
• Sensitive Connection Works

6. • High Initial Investment: For installing a Precast Concrete plant, heavy and sophisticated machines are
necessary which requires high initial investment. A large scale of precast construction projects must be
available to ensure sufficient profit.
• Transportation Issue: The construction site can be at a distant location from the Precast Concrete plant.
In that case, the precast members must be carried to the site using trailers. In many cases, the reduced
costs of Precast Concrete is compensated by the transportation cost.
• Handling Difficulties: Proper care and precaution have to be taken for handling precast concrete. Usually,
precast members are heavy and large which makes it difficult to handle without damage. Generally,
portable or tower cranes are used to handle the precast members.
• Modification: Limitation In case of precast structures, it is difficult to modify the structure. For
example, if a structural wall is to be dismantled for modification it will impact the overall stability of the
structure.
• Sensitive Connection Works: Assembling of the precast members is one of the key points for ensuring
strong structural behavior. Connections between several structural members must be supervised and done
properly to ensure the intended behavior of the connection such as simple, semi-rigid or rigid connections.
Besides this, faulty connections may lead to water leakage and fail sound insulation.

7. CONNECTION
DETAIL
• COLUMN
REINFORCEMEN
T
• BEAM AND
COLUMN DETAIL

8. CONNECTION
DETAILS
• BEAM TO SLAB
AND COLUMN

9. CONNECTION
DETAIL
• COLUMN DETAIL

10. CONNECTION
DETAIL
• SLAB AND BEAM

12. FEATURES OF PRECAST
• Great dimensional accuracy and finishes.
• Better quality critical elements.
• Design flexibility.
• No on-site space for moulds and reinforcement storage.
• Faster erection at site.

13. PRECAST CAST IN SITU
• Elements are manufactured in a controlled
casting environment and have it is easier to
control mix, placement and curing.
• Quality can be controlled and maintained
easily.
• Less labours are required.
• Less skilled labours are required.
• Column, slab etc. elements are casted on site
and hence it is difficult to control mix,
placement and curing in cast-in-situ concrete.
• Quality control and maintenance is difficult.
• More labours are required.
• More skilled labours are required.

14. • Increase in strength can be achieved by
accelerated curing.
• Elements can be cast in controlled condition.
• On site strength test is not required.
• Elements can be cast in advance and held until the
hour you need them, thereby saves time
• Weather condition has no effect on casting work.
• Speedy construction is possible.
• Precast concrete is cheaper form of construction
if large structures are to be constructed.
• Total construction time is less as compared to
cast-in-situ.
• Precast concrete does not offer a monolithic
architectural character.
• Elements of varying lengths and shape can be
developed.
• Elements are cast in open environment.
• On site strength test is required.
• Elements cannot be casted in advance.
• Weather condition can delay the casting work.
• Speed is less as elements are casted at site..
• In situ concrete is cheaper form of construction
for small structures.
• Total construction time is more as compared to
precast.
• In situ concrete offers a monolithic architectural
character.
• There is constraint in length and shape of
element.
• Less maintenance cost.
• Less number of joints present in structural
system.

15. • Precast concrete construction is quick as it can be
installed immediately and there is no waiting for it to
gain strength.
• Higher maintenance cost.
• Large number of joints in structural system.
• Less resistant to Earthquake and wind forces not
recommended where seismic loads are dominant.
• To construct one needs a skilled and technical
contractor.
• High Strength concrete can be used because it is in
controlled condition.
• Precast concrete requires heavy machinery and
cranes for handling i.e. lifting and installation of
heavy elements
• In precast concrete construction, details at the joint
become very critical and needs careful attention.
• The elements have to be designed for handling stress
or loads during handling, which may or may not
increase steel.
• In situ concrete construction is slow as gaining of strength requires time.
• Increase in strength at situ by accelerated curing is a difficult task.
• More resistant to earthquake and wind forces.
• Local contractors can also build the structure.
• It will difficult to use High Strength Concrete as it depends on site
condition and resources available.
• Cast-in-situ concrete does not require such handling equipments.
• No serious attention is required for joints in cast-in-situ concrete
construction.
• Elements are not to be designed for any such loads or stress.

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