PLACING AND COMPACTION

1. Seminar On
PLACING AND COMPACTION OF
CONCERTE
By,
Chiranthan y
Department of Civil Engineering
MAHARAJA INSTITUTE OF TECHNOLOGY
THANDAVAPURA

2. PLACING
It is a process of depositing a fresh
concrete on its final position.
• Before placing concrete form work must be
checked for its rigidity and cleanliness .
• Concrete should not be dropped from height as
it causes segregation or piled up in heaps .
• The wheel barrow or vibrating needle should
not be allowed to run over the placed concrete.

3. The cautious to be taken for
placing .
• The concrete broadly categorized according to type
of work

4. 1. Foundation bed
To construct a foundation we have to
excavate earth trenches.
After excavation of trenches we check
the bed of the earth trench
The bed of the trench should be free
from roots, organic matters and loose
earth
Trenche is wetted by spraying water to
avoid the loss of water from concrete
The chutes are used for placing
concrete in deep trenches.

5. 2. Columns and deep beams
While placing of concrete in columns
or deep beams it is not suggested to allow
the free fall of concrete more than a meter
unless the mix is designed to be dropped
• The free fall of concrete results in
segregation.
• Then we use the tremie pipe to dropped
cement concrete to the cover blocks and
we also use the sloping board.

6. TREMIE PIPE

7. Tremie
pipes

8. COMPACTION
Compaction is the process of removing
entrapped air bubbles from the fresh concrete
and improving the packing of aggregates to form
dense concrete.
If air bubbles present in structure or placed
concrete Then honey combing or blow holes
are caused in concrete.
This effects the strength of concrete
The approximate air content in fresh concrete
is 25% which is reduced to 2-5% by
compaction.

10. HAND COMPACTION
It is a type of compaction
done by manually.
There are three types in this
compaction process
1.Roding
2.Ramming
3.Tamping

11. 1. Rodding
A single steel rod is used for pocking
the fresh Concrete.
2. Ramming
A flat metal piece attached to a
hammer is used to hit on the surface of
concrete.
Compaction process of this type is done in
floor construction
3.Tamping
In thin cross sectional surface tamping
is done tamping in the surface of the concrete
with a wooden bar is used.

12. INTERNAL VIBRATOR
Vibration takes place inside the concrete mix.
Needle vibrator
Poker vibrators essentially consist of
vibrating needle which is inserted into the fresh
concrete
A loosely kept mass attached with the cable inside
the needle hits on the inner surface of the hallow
needle on rotation driven by a motor the hitting
action generates vibration in the needle.
The compaction of concrete takes place due to the
vibration of the needle.

13. NEEDLE VIBRATOR

14. EXTERNAL VIBRATOR
Vibration takes place on the surface of the
concrete.
Form vibrator
This is used for vibrating thin section of concrete
members.
Table vibrator
Vibrating tables are used for the compaction of
concrete in the production of precast members.

15. FORM VIBRATOR

16. TABLE VIBRATOR

17. Platform vibrator
• It is used in smaller thickness structures
construction like slabs.
•The compaction of concrete is done by applying
vibration at the surface the platform vibrator
consists of metal platform attached with vibrating
motors.
Screed vibrator
Screed is also used for the compaction of
concrete up to a depth of 100mm the screed
consists of a long beam attached to a frame and
vibrating motor.

18. PLATFORM VIBRATOR

19. SCREED VIBRATOR

20. CONCLUSION
• Placing and compaction of concrete is
interdependent activities and are carried out
simultaneously
• The compacted concrete is dense, strong and
durable.