What is bricks and its classification and properties.
* introduction:- in this topic we know what is bricks and its classification and properties .bricks are one of the oldest material and it can be extensively used in civil work at present because it has high strength durability and easy available in all present location, it is manufactured by moulding of burnt clay or concrete block by mixture of sand and lime or of Portland cement but in this topic I will discuss about only clay red brick and what is bricks and its classification and properties.
* uses of bricks:- bricks are used for building up of exterior and interior wall partition, footing, pavement making, retaining wall formation along hilly area and other load bearing structure.
* size of bricks:– there are two type size of brick in India one is modular brick and second is standard Indian size brick .
1)size of modular brick is about 190-90-90 mm and
2)Indian size bricks are 230 -115 -75 mm.
* purpose of indent :- in top face of middle part Indian red clay burnt brick have indent like structure called as frog structure. it is about 1.2 CM Deep and provided in the brick size. that frog should be 100-40 -10 mm .purpose of providing frog is to keep holding for cement mortar and gaining its strength.
*Classification of bricks:-
A) according to field practice red clay bricks are classified into 5 class
1) first class bricks
2)second class bricks
3)third class bricks
4)fourth class bricks
5) special type of bricks
B) BIS (Bureau of Indian standard) bricks are classified according to their strength.
1) first class bricks:–
●these bricks are table moulded and burnt in kilns or high rise chimney
●it is burnt in Chimney are of deep red ,Cherry or copper colour
●its surface should be a smooth rectangular with parallel side sharp and straight edge with square corner
●and it should be free from cracks and stone
●it has uniform texture
●and water absorption capacity is about 15 to 17% of its dry weight when immersed in water for 24 hour is allowed
●it has metallic ringing sound come when to bricks are a struck against each other
●and no impression should be left on the brick when scratched is made by our fingernail
● and crushing strength is about 10 N/mm2
* uses of first class bricks:
it has all importance bricks work, it should be used for exposed face of masonry structure like flooring and reinforced brickwork.
2) second class bricks:
◆these bricks is ground moulded and burnt in kilns or Chimney
◆these have small cracks
◆and water absorption capacity is little higher than first class bricks it has about 18 to 20% of dry weight of bricks when immersed in water for 24 hour
◆and crushing strength is more and equal to 7 N/mm2
* uses second class bricks :-
it should be used for unimportant hidden masonry work and centring of reinforced brick
3) third class bricks:-
◆these bricks are grounded moulded and burnt in clamps
●these bricks are soft and red yellow coloured
◆ it produce dull sound when struck one against other
◆ it has higher water absorption capacity about 20 to 25% of its dry weight when it is immersed in water for 24 hour
◆these have rough surface of a regular size
*uses of 3rd class bricks :- it should be used for temporary masonry structure.
4)4rth class bricks:-
this bricks are over burnt and badly disorted in shape and size and come in the reddish black colour ,these bricks are used for filling of ground area for floor.
5) special type of bricks:-
the burnt clay bricks having strength more than 40 Newton/mm2 are known as heavy break and it can be used for heavy structural like Dam Bridge foundation for industrial building and factory it has only 5% water absorbing capacity.
B) BIS ( Bureau of Indian standard )bricks are classified in different category according to their comprehensive strength.
1) class 35 :-it has compressive strength about 35 Newton/mm2
2) class 30 :-it has comprehensive strength about 30 Newton /mm2
3)class 25 :-it has comprehensive strength about 25 Newton/mm2
4)class 20:- it has comprehensive strength 20 Newton /mm2
5)class 17.5 :-it has compressive strength 17.5 Newton/mm2
6)class 15 :-it has comprehensive strength 15 Newton/mm2
7)class 12.5:- it has comprehensive strength 12.5 Newton/mm2
8)class 10 :-it has comprehensive strength about 10 Newton/mm2
9)class 7.5 :-it has compressive strength 7.5 Newton/mm2
* properties of good bricks:–
◆Bricks should be free from stone grit and organic material
◆ it should have uniform shape size with rectangular with sharp edge and Square corner
◆water absorbing capacity should be low
◆bricks should be Red copper colour
◆it should be produce metallic sound when struck against one another
◆no impression is made on bricks by finger nail
◆It has good comprehensive strength
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