Brick: A brick is an artificial kind of stone made of clay whose chief characteristics are a plasticity when wet and stone like hardness after being heated to high termperatute.
Characteristics
of Good Brick:
1. Bricks
should be uniform in colour .size and shape.
2. They
should be sound and compact.
3 They
should be free from cracks and other flaws such as air bubbles.stone nodules etc.
4. They
should not absorb more then 1/5 of theie own wt of water when immerged in water
for 24 hours (15 to 20% dry wt.).
5. The compressive strength of bricks should be in the range of 5.000 to 8.000 psi.
6. The percentage of soluble salts (sulphates of calcium, magnesium, sodium and potassium) should not exceed 2.5% in burnt bricks, because the presence of excess soluble salts causes efflorescence.
7. They
should be neither overburnt or underburnt.
8.They
weight should be generally 6 lbs per brick and the weight per cu ft should not
be less than 125-lbs.
9.they should
have low thermal conductivity as it is desirable than the buildings built of
them should be cool in summer and warm in winter.
10.They
should be non –lnflammable and incombustible.
Field
Tests of Bricks:The
following are the test that are generally performed in the field to determine
the quality of good bricks:
1.Take a
brick and try to make mark on the surface by nil.if you can make it. It is not.
a good brick. If not. it is very hard and compact.
2.Take a
brick and strike it with a hammer. If it gives
clear ringing or metallic sound.
It is a good brick. if not a bad one.
3 . Take two brick and form a tee (T) and drop from a height
of on a more or less solid surface .if they break they are not good bricks. If
they remain unbroken . they are good bricks.
Size of Bricks:
| Standard | Metric (mm) | Imperial (inches) |
|---|---|---|
 Australia | 230 mm × 110 mm × 76 mm | 9.1 in × 4.3 in × 3.0 in |
 Denmark | 228 × 108 × 54 | 9.0 × 4.3 × 2.1 |
 Germany | 240 × 115 × 71 | 9.4 × 4.5 × 2.8 |
 India | 228 × 107 × 69 | 9.0 × 4.2 × 2.7 |
 Romania | 240 × 115 × 63 | 9.4 × 4.5 × 2.5 |
 Russia | 250 × 120 × 65 | 9.8 × 4.7 × 2.6 |
 South Africa | 222 × 106 × 73 | 8.7 × 4.2 × 2.9 |
 Sweden | 250 × 120 × 62 | 9.8 × 4.7 × 2.4 |
 United Kingdom | 215 × 102.5 × 65 | 81⁄2 × 4 × 21⁄2 |
 United States | 194 × 92 × 57 | 7.6 × 3.6 × 2.2 |
Classification of Bricks:
1.First
Class B ricks: They should be of uniform size and colour. thoroughly and
evenly burnt. They should ring clearly
when struck. With a hammer or another brick. They should be well shaped with
even surfaces and without cracks. rainspots or flaws of any kind. They should
not absorb more than one sixth of their weight of water when wet in water for
24 hours.
2.Second Class Bricks: These bricks must possess the hardness and colour of first
class bricks but are slightly irregular in shape, size or rough on the surface.
3.Third
Class Bricks:These
are bricks which are not sufficiently all-burnt sufficiently and of uniform
shape and size for use in un- important constructions.
4. First Class Bats:These are broken
bricks of the same quality as first and second class brick.
5. Second Class Bats : These are
broken bricks of the quality as third class bricks,
6.Picked Jhama Bricks : These bricks are uniformly vitrified
throughout. But must be of good shape. heavy and of selected quality .They must not be spongy.
7. Jhama Bricks: These are well- burnt
bricks but not quite so well shaped as picked jhama bricks. They must not be
spongy and must be free from cinders and projecting lumes and of fairly good
shape.
8.Jhama Bats: These are broken bricks
of the classes picked jhama and jhama bricks.
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