Classification of bricks based on properties

Classification of bricks based on their physical and mechanical properties

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.
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.
Water absorption should be 12–15% of its dry weight when immersed in cold water for24 hours.
The crushing strength of the brick should not be less than 10 N/mm2.
This limit varies with different Government organizations around the country.