Bricks Manufacturing: Burning

 Bricks are burned at high temperature to gain the strength, durability, density and red color appearance.All the water is removed at the temperature of 650 degrees but they are burnt at an temperature of about 1100 degrees because the fusing of sand and lime takes place at this temperature and chemical bonding takes between these materials after the temperature is cooled down resulting in the hard and dense mass. Bricks are not burnt above this temperature because it will result in the melting of the bricks and will result in a distorted shape and a very hard mass when cooled which will not be workable while brickwork. Bricks can be burnt using the following methods:

(a) Clamp Burning

(b) Kiln Burning

(a)Clamp Burning:

Clamp is a temporary structure generally constructed over the ground with a height of about 4 to 6 m. It is employed when the demand of the bricks is lower scale and when it is not a monsoon season. This is generally trapezoidal in plan whose shorter edge among the parallel sides is below the ground and then the surface raising constantly at about 15 degrees to reach the other parallel edge over the ground.A vertical brick and mud wall is constructed at the lower edge to support the stack of the brick. First layer of fuel is laid as the bottom most layer with the coal, wood and other locally available material like cow dung and husk.Another layer of about 4 to 5 rows of bricks is laid and then again a fuel layer is laid over it. The thickness of the fuel layer goes on with the height of the clamp.

After these alternate layers of the bricks and fuel the top surface is covered with the mud so as to preserve the heat.Fire is ignited at the bottom, once fire is started it is kept under fire by itself for one or two months and same time period is needed for the cooling of the bricks.

Disadvantages of Clamp burning:

1. Bricks at the bottom are over-burnt while at the top are under-burnt.

2. Bricks loose their shape, and reason may be their descending downward once the fuel layer is burnt.

3. This method cannotemploy for the manufacturing of large number of bricks and it is costly in terms of fuel because large amount of heat is wasted.

4. It cannot be employed in monsoon season.