First of all various books and
journals were collected for reference and were studied before starting the
project work for having an idea about how the project should be. In this
project an alternative building bricks are introduced. So, first the basic and
essential characteristics of bricks were studied. And the details about the new
technique what was used in this project i.e., papercrete, was collected from
the journals.
BRICKS
The
bricks are obtained by molding clay in a
rectangular blocks of uniform size and then by drying and burning the blocks.
As the bricks are of uniform size, they can be properly arranged and further,
as they are in lightweight, no lifting appliance is required for them. The
common brick is one of the oldest building material and it is extensively used
at present as a leading material in construction. In India, process of brick
making has not changed since many centuries except some minor refinements.
There has been hardly any effort in our country to improve the brick-making
process for enhancing the quality of bricks.
A
brick is generally subjected to the following tests to find out its suitability
for the construction work.
Absorption
A
brick is taken and it is weighed dry. It is then immersed in water for a period
of 16 hours. It is weighed again and the difference in weight indicates the
amount of water absorbed by the brick. It should not, in any case, exceed 20%
of weight of dry brick.
Crushing Strength
The
crushing strength of a brick is found out by placing it in a compression-testing
machine. It is compressed till it break, as per BIS: 1077-1957, the minimum
crushing strength of brick is 3.50 N/mm2 .The brick with crushing
strength of 7 –14 N/mm2 are graded as ‘A’ and those having above 14
N/mm2 are graded as ‘AA’.
Hardness
In
this test, a scratch is made on the brick surface with the help of fingernail.
If no impression is left on the surface, the brick is treated to be
sufficiently hard.
Presence of soluble salts
The
soluble salts, if presents in brick will cause efflorescence on the surface of
bricks. For finding out the presence of soluble salts in brick, it is immersed
in water for 24 hours. It is then taken out and allowed to dry sunshade. The
absence of grey or white deposits on its surface indicates absence of soluble
salts.
If
the white deposit covers about 10% surface, the efflorescence is said to be
slight and it is considered as moderate, when the white deposit cover about 50%
surface. If grey or white deposits are found on more than 50% of surface, the
efflorescence becomes heavy and it is treated as serious, when such deposits
are converted into powdery mass.
Shape and size
In
this test, a brick is closely inspected. It should be of standard size and its
shape should be truly rectangular with sharp edges. For this purpose, 20 bricks
of standard size (190mm X 90mm X 90mm) are selected at random and they are
stacked length wise, along the width and along the height.
For
a good quality brick, the results should be within the following permissible
limits:
Length:
3680mm to 3920mm
Width
: 1740mm to 1860mm
Height:
1740mm to 1860 mm
Soundness
In
this test, two bricks are taken and they are struck each other. The bricks
should not break and a clear ringing sound should be produced.
Structure
A
brick is broken and its structure is examined. It should be homogeneous,
compact and free from defects such as holes, lumps etc.,.
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