Precast Cement Concrete Block Construction - Seminar Report, PPT, PDF For Civil Engineering
Precast Cement Concrete Block Construction - Seminar Report, PPT, PDF For Civil Engineering
Precast Cement Concrete Block Construction - Seminar Report, PPT, PDF For Civil Engineering
MATERIALS
Mould:-
Moulds shall be fabricated using mild steel plates and mild steel
angles for stiffening the plates.
The mould should be either fixed type or (box with four side walls
fixed at corners, and top and bottom open) or split type.
Proportion:-
Casting:-
Curing:-
Drying:-
After curing, the blocks shall be dried for a period of two to four
weeks depending upon weather before being used on the work. The
:
blocks shall be allowed to complete their initial shrinkage before they
are laid in a wall.
Dimensions:-
The maximum variation in the length of the units shall not be more
than +5mm and maximum variation n height and width of unit, not
more than +3mm.
Density:-
Construction Of Masonry
Wetting of Blocks:-
Laying:-
All course shall be laid truly horizontal and vertical joints made truly
vertical Blocks shall break joints with those above and below for not
less than quarter of their length .Precast half length closer and not
cut from full size blocks shall be used .For battered face ,bedding
shall be at right angle to the face unless otherwise directed .
Care shall be taken during construction to see that edge of block are
not damaged.
Intersecting Walls:-
:
when two wall meet or intersect and the course are to be laid up at
the same time , a true masonry bond between at least 50% of the
units at the intersecting is necessary. when such intersecting walls
are laid up separately, pockets with 20mm maximum vertical spacing
shall be left in the first wall laid .The corresponding course of the
second wall shall be built into these pockets.
The course immediately below the roof slab shall be built with solid
blocks .The top of the roof course shall be finished smooth with a
layer of cement and coarse sand mortar 1:3,10 mm thick and covered
with a thick coat of white wash or crude oil , to insure free movement
of slab.
Piers:-
The top course of block in the pier shall be built in solid blocks.
Hollow concrete block shall not be used for isolated piers, unless
their hollows are specified to be filled with a cement concrete.
Fixtures,fitting ,etc. shall be built into the masonry in cement and
carse sand mortar 1:3 while laying the blocks where possible .Hold
fasts shall built into the joints of the masonry during laying .
Holes, chases, sleeves , openings etc. of the required size and shape
shall be fprmed in the masonry with special blocks while laying,for
fixing pipes,service lines ,passage of water etc. After service lines
,pipes,etc. are fixed ,voids left ,if any , if any , shall be filled up with
cement concrete 1:3:6 (1 cement :3 coarse sand :6 stone aggregate
2 mm nominal size ) and neatly finished .
Finishes:-
Rendering shall not be done to the walls when walls are wet . Joints
:
for plastering or pointing as specified shall be raked to a depth of 12
mm. joints on internal faces, unless otherwise indicated ,shall be
raked for plastering . if the internal faces of masonry are not to be
plastered the joints shall be finished flush as the work proceed or
pointed flush where so indicated
ADVANTAGES
4. The moulds employed for preparing the pre-cast units are of steel
with exact dimensions in all directions. These moulds are more
durable and they can be used several times.
5. The pre-cast articles may be given the desired shape and finish
with accuracy.
DISADVANTAGES
CONCLUSION
Precast concrete block usually are much larger than ordinary bricks
and so are much faster to lay for a wall of a given size. Furthermore,
cinder and concrete blocks typically have much lower water
absorption rates than brick. They often are used as the structural
core for veneered brick masonry, or are used alone for the walls of
factories, garages and other "industrial" buildings where such
appearance is acceptable or desirable. Such blocks often receive a
stucco surface for decoration
:
REFERENCES
4. www.artcretewales.co.uk/case-studies.html
5. www.leebrickandblock.com/2006/10/
6. www.askthebuilder.com/505_Concrete_Block.shtml
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