1. UNBURNT BRICKS:
The unburnt bricks are those bricks which are dried with the help of heat received from the sun after the process of moulding. It is also called sun dried bricks. These bricks can only be used in the construction of temporary and cheap structures. These types of bricks should not be used at place exposed to heavy rains.
2. BURNT BRICKS:
Burnt bricks are prepared by burning the brick mould in the kilns inside the factory. These are the most commonly used bricks for construction works. They are classified into following four categories.
(i) First Class Bricks:-
They are made from good quality earth, free from saline deposits. These bricks are table moulded and of standard shape and they are burnt in kilns. The surface and edges of bricks are sharp, square, smooth and straight. These bricks are mainly used for face worked structure or used for superior work. They should be of good color and free from flaw, cracks, chips and stones. Its compressive strength shall not be less than 140kg/cm2 and they shall not absorbed water more than 20 percent when immersed in water for 24 hours.
(ii) Second Class Bricks:-
The second class bricks are ground moulded and also burnt in kilns. The surface of these bricks are slightly rough and irregular. These bricks may have hair cracks and their edges may not be sharp and uniform. Its compressive strength shall not be less than 70kg/cm2 and they shall not absorbed water more than 22 percent when soaked in water for 24 hours. These bricks are commonly used at a place where brick work is to be provided with a coat of plaster.
(iii) Third Class Bricks:-
The third class bricks are ground moulded and burnt in clamps. These bricks are not so hard and they have rough surface with irregular and blunt edges. On striking together, they produce a dull thud sound. Its compressive strength lies between 35-70kg/cm2 and water absorption between 22-25 percent. They are mostly used in ordinary type construction and at a place where rainfall is not heavy.
(vi) Fourth Class Bricks:-
These are over burnt bricks with irregular shape and dark color. They are quite strong in compressive strength generally above 150kg/cm2 and low in porosity and absorption. These bricks are used as aggregate for concrete in foundation, brick floors, surkhi, roads etc.
The unburnt bricks are those bricks which are dried with the help of heat received from the sun after the process of moulding. It is also called sun dried bricks. These bricks can only be used in the construction of temporary and cheap structures. These types of bricks should not be used at place exposed to heavy rains. 2. BURNT BRICKS:
Burnt bricks are prepared by burning the brick mould in the kilns inside the factory. These are the most commonly used bricks for construction works. They are classified into following four categories.(i) First Class Bricks:-
They are made from good quality earth, free from saline deposits. These bricks are table moulded and of standard shape and they are burnt in kilns. The surface and edges of bricks are sharp, square, smooth and straight. These bricks are mainly used for face worked structure or used for superior work. They should be of good color and free from flaw, cracks, chips and stones. Its compressive strength shall not be less than 140kg/cm2 and they shall not absorbed water more than 20 percent when immersed in water for 24 hours.
(ii) Second Class Bricks:-
The second class bricks are ground moulded and also burnt in kilns. The surface of these bricks are slightly rough and irregular. These bricks may have hair cracks and their edges may not be sharp and uniform. Its compressive strength shall not be less than 70kg/cm2 and they shall not absorbed water more than 22 percent when soaked in water for 24 hours. These bricks are commonly used at a place where brick work is to be provided with a coat of plaster.
(iii) Third Class Bricks:-
The third class bricks are ground moulded and burnt in clamps. These bricks are not so hard and they have rough surface with irregular and blunt edges. On striking together, they produce a dull thud sound. Its compressive strength lies between 35-70kg/cm2 and water absorption between 22-25 percent. They are mostly used in ordinary type construction and at a place where rainfall is not heavy.
(vi) Fourth Class Bricks:-
These are over burnt bricks with irregular shape and dark color. They are quite strong in compressive strength generally above 150kg/cm2 and low in porosity and absorption. These bricks are used as aggregate for concrete in foundation, brick floors, surkhi, roads etc.
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