We can use water absorption test, hardness test, shape & size, crushing strength test, soundness test, etc. to check the brick quality. In water absorption test, we dip the brick for 16 hours in water. If weight of brick after dipping in water doesn’t exceed by 20%, it can be considered as first class brick, if below 22.5% it can be considered as second class brick, if below 25% it can be considered as third class brick. In crushing test, it crushing strength should be minimum of 10 N/mm2 for first class brick, 7.5 N/mm2
for second class bricks. In hardness test, we scratch the brick with nails. It should be scratch free. In soundness test we check the metallic sound by striking two bricks with each other
