According to physical requirements bricks are classified as:1) First-class bricks
2) Second class bricks
3) Third class bricks
4) Fourth class bricks

1) First-class bricks:

 

The qualities of first-class bricks are:

• First-class bricks are table moulded, well and uniformly burnt, deep red or copper coloured.

 

• bricks are burnt in kilns

 

• Size is exactly 190×90×90mm

 

• The edges are square and sharp

 

• These bricks have a Uniform texture

 

• The crushing strength should be about 10N/mm2

 

• Water absorption should not be more than 20% after 24 hours of immersion

 

• The bricks should produce a clear metallic sound when struck with each other

 

• The brick should not break when dropped from a 1-metre height.

 

Uses of first-class bricks:

• Used for superior work
• Used for reinforced brickwork
• Used for load-bearing walls.
• Used for pavements and flooring.

 

 

2)Second class bricks:

 

These bricks are ground moulded and they are burnt in kilns.

The qualities of second class bricks are:

• The brick is well burnt

 

• Water absorption is not more than 22% of its own weight after 24 hours of immersion

 

• These bricks give a clear metallic ringing sound when struck with each other

 

• These bricks should not show signs of efflorescence.

 

• The shape and size should be uniform

 

• The crushing strength should not be less than 7N/mm2

 

Uses of second class bricks:

• Used in RCC work
• Used for load-bearing walls
• These bricks are provided with a coat of plaster.

3)Third class bricks:

 

These bricks are ground moulded and are burnt in clamps. These bricks are not properly burnt.

The qualities of third class bricks are:

• These bricks are under burnt

 

• These bricks are not hard and surface what is rough

 

• They are soft and light-coloured

 

• They have many signs of efflorescence

 

• They give a dull sound when struck with each other

 

• The water absorption should not be more than 25%

 

• They have a compressive strength of 3.5N/mm2

 

• They do not have sharp edges and corners

 

• The texture is not uniform.

Uses of third class bricks:

• Used for in-important structure
• Used for construction of walls of low height
• Used in areas where rain is not heavy
• Used for temporary structures.

4) Fourth class bricks:

 

These are over burnt bricks with irregular shapes and dark colours.

Qualities of fourth class bricks:

• These bricks are a dark bluish colour
• These bricks have a compact structure