Bricks are of two sizes ;
- Modular bricks : 19cm *9cm * 9cm (actual size )
- Non modular size : 20 cm* 10 cm* 10 cm ( commonly used; size of bricks with mortar )
- When two bricks are striked against each other it Should produce clear ringing sound. This brick is known to have sufficient soundness and without crack.
- When a brick is dropped from certain height of 1m on a levelled surface it shouldn’t be broken down in to pieces which depicts the toughness of the brick.
- When a scratch is made on the surface of the brick ; any impression on the nail shouldn’t be produced.
- Minimum strength of the brick used in construction work should be 3.5 N/mm^2
- A first class brick should have water absorption is less than 20% otherwise it will absorb water from mortar causes crack in it.
- A good quality brick should be of high temperature resistance. According to this properties;
- Heavy duty brick : 1450°C – 1650°C
- Medium duty brick : 1000°C – 1400°C
- Low duty brick : 850°C .
The bricks may contain harmful ingredients like alkalies, excess magnesia and excess lime. To know these values we have to do lab tests.