learn the 4 types of underwater concreting techniques and also short description how geogrid sheets are placed in soil reinforcement techniques

3. 1.TREMIE METHOD

5. .
• Before concreting air and water must be
excluded keeping the pipe full of concrete
all the time.
• For this the funnel and the pipe should have
equal capacity.
• Firstly plug is inserted in the pipe with
pressure of fresh concrete so that the air is
displaced

9. The buckets are usually fitted with drop-bottom or
bottom-roller gates which open freely outward when
tripped. The bucket is fully filled along with concrete
and its top covered along with a canvas cloth or a
gunny bag to avoid the disturbance of concrete as
the bucket is lowered within water.

13. PLACING IN
BAGS

15. In this method, properly concrete
filled bags are lowered into water
and placed carefully in a header
and stretcher fashion as in brick
masonry with the help of divers.
. A work is slow and laborious, as
the accurate positioning of the
bags in place can be only
accomplished by the divers.
The bags and labour necessary to
fill and tie them are relatively
expensive. This method is only
suited for placing the concrete in
shallow water.

16. In this method, the aggregate should be wetted
before placing in position. This method is also called
as grouted concrete. It consists of placing the
coarse aggregate only in the forms and thoroughly
compacting it to form a pre-packed mass.

17. In this method, the aggregate should be
wetted before placing in position. This
method is also called as grouted
concrete. It consists of placing the
coarse aggregate only in the forms and
thoroughly compacting it to form a pre-packed
mass.
This mass is then grouted with the cement
mortar of the required proportions. The
mortar that grouts the concrete displaces
water and fills the voids. Dense and compact
concrete should be prepared by using well
graded aggregates
The maximum size of aggregate
conveniently used is 80 mm. The coarse
aggregate may also be allowed to fall
from heights of up to 4 m, without
causing any appreciable segregation.
Just shutter vibrations could be used for
compact the coarse aggregate.
An air-entraining agent is also added to the mortar
to entrain about 4% of air. A small variation of the
procedure of preparation of the cement mortar for
grouting leads to a process called colcrete. In this
procedure, the mortar grout is prepared in a
special high-speed mixer. No admixtures are used
within this procedure.
A mortar consists of fine sand, pozzlanic
filler material and as chemical agent that
serves the penetration, early setting of
cement, and the dispersion of particles
and to increase the fluidity of mortar.

18. • The grout pressure will be about
0.2 to 0.3 MPa. The quantity of
grout should be estimated from the
void contents of the coarse
aggregates. The pre-packed
concrete has lower drying
shrinkage and higher durability,
especially freezing and thawing
resistance compared to ordinary
concrete for the same proportions.
• (c) Pumping the grout
into aggregate mass from
bottom at carefully
designed positions
through a network of
pipes. The formwork
should be constructed at
the top of the coarse
aggregate in this method
• (b) The grout could be
poured on the top surface
of aggregate and allowed to
penetrate to the bottom.
The method is particularly
useful for grouting thin
sections.
• (a) The mould
could be filled with
grout and the
coarse aggregate
can be deposited in
the grout.
METHODS
OF
PREPACKED CONCRETE

20. USING GEOTEXTILES
• Geotextiles are
fabrics which are
used to filter,drain or
reinforce the soil.
1.GEOTEXTILES
They are made of
polypropylene

21. MAJOR FUNCTIONS
OF GEOTEXTILES

22. GEOGRIDS ARE
USED FOR
WALL
CONSTRUCTION
DRAINAGE
CONSTRUCTION

23. 1.GEOGRIIDS ARE
PLACED ON THE
SUBSOIL.
• 2.THEN THE
ELEVATIONS ARE
MARKED .

29. THAN
K
YOU!