To know the quality of bricks following tests can be performed-
- Water Absorption test
- Crushing strength test
- Hardness test
- Shape and size
- Color test
- Soundness test
- Structure of brick
- Efflorescence Test
1. WATER ABSORPTION TEST-
This test is conducted on brick to find out the amount of moisture absorbed by brick under extreme condition. In this test a sample of dry brick are taken and weighed and immersed in fresh water at a temperature of 27'C for a period of 24 hours. After 24 hours the specimen taken out and wiped with cloth. The weight of sample in wet condition is taken, the difference in weight indicates the amount of water absorbed by brick. For a good quality brick the amount of water absorption should not exceed 20 percent of weight of dry brick.
M1- Weight of dry brick
M2- Weight of wet brick
2. CRUSHING STRENGTH TEST-
This test is done to know the load carrying capacity of brick under compression. The brick specimen immersed in water for 24 hours, remove the specimen and drain out surplus moisture at room temperature. The frog of the brick is filled with cement mortar (1:3) and stored in damp jute bag for 24 hours and immersed in clean water for 24 hours. The specimen is placed in compression testing machine and load is applied axially at the uniform rate of 14N/mm2 till failure occurs and note the maximum load at failure. For a good quality brick the crushing value should not be less than 105 kg/cm2.
3. HARDNESS TEST-
In this test a scratch is made on brick surface with the help of finger nail. If no impression is left on the surface, the brick is sufficient hard.
4. SHAPE AND SIZE TEST-
In this test 20 bricks of standard size are randomly selected and stacked along lengthwise, widthwise and heightwise. Bricks are closely inspected to check it should be of standard size and truly rectangular with sharp edges
5. COLOUR TEST-
A good quality brick should posses bright and uniform color throughout its body.
6. SOUNDNESS TEST-
In this test two bricks are taken randomly and struck with each other they should produce clear ringing sound.
7. STRUCTURE OF BRICK-
In this test a brick is broken and closely observed. It should be homogeneous, compact and free from defects such as lumps, holes etc.
8. EFFLORESCENCE TEST-
This test is used to find out the presence of soluble salts in brick. In this test a brick is immersed in fresh water for 24 hours. It is then taken out from water and allowed to dry in shade. If white and grey layer is not visible on brick surface it indicates absence of soluble salts and useful for construction. If the whitish layer visible about 10% of brick surface then the presence of alkalies is in acceptable range. If that is about 50% of surface then it is moderate. If the alkalies presence is over 50% then the is severely affected by alkalies. 