concrete hollow block masonry
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Concrete masonry BLOCKS Cement concrete masonry blocks have been in existence for
centuries.
Revolutionary changes in manufacturing technology and materialsciences have made multi sized, shaped, colours and textured blocks
a reality.
They are used as both structural and non-structural components and
have been the preferred building blocks in the western world.
They are fast replacing traditional bricks and other masonry productsin India too.
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TYPES OF CONCRETE MASONRY
BLOCKSConcrete Masonry Blocks can either be
Hollow or Solid
Load Bearing or Non-load Bearing
Light weight or Dense
Shield concrete blocks are used in low and high rise buildings, forbasements, exterior and interior walls and partitions.
The two types of concrete blocks are, Regular concrete blocks
Light weight concrete blocks
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HOLLOW BLOCK UNITS Regular concrete blocks are precast cement concrete blocks made
from strong aggregate and used for load bearing walls.
For partial load bearing and non load bearing walls light weight
aggregates are used to make the blocks. Steam curing is adopted generally since it enables these blocks to be
laid within a short period after casting.
Concrete blocks are manufactured based on the job requirements.
Hence no standard size of concrete blocks. Concrete Association of India (CIA) recommends face thickness
should not be less than 5cm and net area should be at least 55 to 60%
of gross area.
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COMMON SIZES OF BLOCKSTYPE LENGTH BREADTH HEIGHT
SIZE A 39 30 19
SIZE B 39 20 19
SIZE C 39 10 19
TOLERANCE 3mm 1.5 mm 1.5 mm
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LAYING OF CONCRETE HOLLOW
BLOCK MASONRYCONSTRUCTION OF WALLS
A mortar bed is spread on the foundation concrete and leveled tohave an uniform thickness everywhere.
The corner block is first placed and positioned accurately. Mortar isapplied to other end and one block is positioned to the end andaligned.
The level of the course is checked after placing a few blocks.
If necessary blocks are tapped with additional mortar such thatmortar thickness is 2cm and on the ends.
The first course is checked to be in plumb before placing second andadditional courses.
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BLOCK WALL MODEL
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As done in rick laying the successive courses are laid in such mannerto break the joints vertically.
For vertical joints the mortar is applied to projection at the sides of
the block.
The courses are built starting from the corners only.
Verticality and horizontality are checked at regular intervals.
Four vertical edges of the final block and the edges of opening are
covered with the mortar and pushed in position.
Face of masonry may be points by running a tool.
Weathered, V-shaped or concave types of joints are recommended toshed water easily.
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CONSTRUCTION OF COLUMNS
Columns areused in places whenever a large pressure to be
transferred through large bearing surface.
Columns form the integral part of the wall or it can be a separate
unit.
The columns are made of standard stretcher and corner blocks or
other special shapes are used.
For stability the hollows within the blocks may be filled with plain or
reinforced concrete.
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CONSTRUCTION OF WINDOW AND
DOOR OPENINGS
Blocks with one hole (jamb) near the opening should be filled with
concrete with wooden plugs.
The door and windows are screwed to the wooden plugs.
It is also fixed with lintel with small dowels of mild steel.
At base of window or door course of solid concrete block masonry is
laid
It is extended to adjacent walls to at least 30cm distance on either
side. Lintels are also hollow channel shaped sections which can be filled
with concrete and steel reinforcement provided at bottom.
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CONSTRUCTION OF REINFORCED
WALLS
It is done by providing vertical reinforcement in the hollow of the
corner block and filled with concrete.
In order to increase the strength of the wall, reinforcement is
provided at the horizontal joints. This provision makes expansion cracks which may occur due to
moisture and change of temperature may be reduced.
Two horizontal bars of 6mm diameter are placed one each on the
face of the wall. Instead of steel rods welded steel mesh may be used wherever
needed.
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JAMB DETAILS FOR HOLLOW
BLOCK WALL
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