Brick are classified into three groups on the basis of their water absorption and strength. First Class Brick They have the compressive strength of 10 N/mm2. The water absorption should not be more than 15% of the self weight within 24 hours of immersion in water.The shape are proper and size are upto the standard. Second Class Brick They have the compressive strength of 7.5 N/mm2. The water absorption should not be more than 20% of the self weight within […]