Bricks are classified as first-class, second class, third class, and fourth class based on their quality.
First Class Bricks
- These are thoroughly burnt and are of deep red, cherry, or copper colour.
- The surface should be smooth and rectangular, with parallel, sharp, and straight edges and square corners.
- These should be free from flaws, cracks, and stones.
- These should have uniform texture.
- The size is standard. The color of these bricks is uniform yellow or red
- No impression should be left on the brick when a scratch is made by a finger nail.
- The fractured surface of the brick should not show lumps of lime.
- A metallic or ringing sound should come when two bricks are struck against each other.
Uses: First class bricks are recommended for pointing, exposed face work in masonry structures, flooring and reinforced brick work.
Second Class Bricks : are supposed to have the same requirements as the first class ones except that
- Small cracks and distortions are permitted.
- A little higher water absorption of about 16- 20% of its dry weight is allowed.
- The crushing strength should not be less than 7.0 N/mm2.
Uses: Second class bricks are recommended for all important or unimportant hidden masonry works and centering of reinforced brick and (RCC) structures.
Third Class Bricks are underburnt. They are soft and light-coloured producing a dull sound when struck against each other. water absorption is about 25 per cent of dry weight.The shape and size are not regular. The color is soft and light red colored.It emits a dull or blunt sound when struck by another similar brick or struck by a hammer. It leaves fingernail expression when one tries to do with the thumbnail.
Uses: It is used for building temporary structures.
Fourth Class Bricks are over burnt and badly distorted in shape and size and are brittle in nature.
Uses: The ballast of such bricks is used for Foundation and floors in lime concrete and road metal.