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Concrete
Block Technology offers a speedier,  cost
effective, environmentally sound alternative to
conventional walling materials. It is based on
the principle of densification of a lean
concrete mix to make a regular shaped, uniform,
high performance masonry unit. Concrete Block
Technology can be easily adapted to suit special
needs of users by modifying design parameters
such as mix proportion, water/cement ratio and
type of production system. It is an effective
means of utilizing wastes generated by stone
crushers, quarrying and stone processing units.
The technology has high potential in areas where
raw materials are easily available.
Business
The Concrete Block Technology package is a
highly profitable business for micro and small
scale building material producers and
construction companies. A total investment of
about Rs. 1,75,000/- assures a net profit of
approximately Rs. 60,000/- per annum. The market
for concrete blocks is growing at a rapid rate,
especially in the areas where burnt bricks are
not easily available or are of poor quality.
Product
The
specifications and the characteristics of a
concrete block depend on the machine used to
manufacture concrete blocks.
The most common size of solid concrete blocks is
300x200x150mm. The basic raw material is cement,
fine aggregate and coarse aggregate.  Very
little water is used. This is possible only with
mechanized compaction and vibration and gives
the block high quality in spite of the lean mix,
which uses very little cement. Weight of a
concrete block is about 18-19 Kgs. Concrete
blocks can be surface engineered by using pieces
of stone or ceramic waste on their face. Another
common type is hollow concrete blocks. They are
made with a richer mix, but offer a number of
advantages, such as lighter weight, easier
handling and facility for conducting or
reinforcement through the hollows.
Unique features of
Concrete Block Technology
 |
Cost
effective compared to other traditional
walling systems |
|
Maximum
utilization of wastes and local
resources |
|
Structural
performance can be engineered |
|
Decentralized
local production |
|
Offers
business opportunities |
Production Process
Concrete blocks are
usually produced using a semi-mechanized
stationary type machine. The other production
systems are - manual moulds that require hand
tamping, a mobile semi-mechanized egg-laying
machine and fully mechanized system that
combines compression and vibration.
High quality machines provide optimum vibration
in the mix so that the ratio of cement used can
be reduced substantially without compromising on
the strength of the blocks. The machine also
compacts and consolidates the mix so that the
blocks are uniform in size and attain desired
physical properties. The blocks are cured for a
minimum period of 14 days, before they are ready
to use. On an average 600-800 blocks can be in 8
hours by 1 skilled and 6-8 semi-skilled workers.
Building with Concrete
Blocks
Concrete blocks can be
used like any other masonry unit to build
foundations, walls, arches and corbels, etc. A
typical concrete block is equivalent to 4.5
bricks, thus construction is faster than with
other masonry units. The  mortar
used is also, less which results in cost saving.
Concrete blocks have been extensively used in
combination with conventional roofing systems
like RCC, RBC, GI sheets, ACC sheets etc. They
are also compatible with other materials like
fired bricks, dressed stone and compressed earth
blocks for composite wall construction.
Acceptability of concrete blocks is very high in
urban areas for all types of buildings. They are
very popular as a long lasting, low maintenance
and investment for institutional and industrial
buildings. The permanence of a cement-based
product is making concrete blocks a preferred
choice in rural areas as well.
Technical Specifications of Concrete Blocks
|
Parameter |
Description |
| Typical
size |
300
x 200 x 150 mm |
| Average
compressive strength at 28 days |
50-110
kg/sq.cm |
| Mix
Proportion |
1:12-14
(1 part cement : 12-14 parts sum graded
aggregates) |
| Water
absorption in 24 hours |
Less
than 10% by weight of block |
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