Classification of Bricks Based on Quality
Based on quality, Bricks are of the following kinds:
1. First Class Brick: The size is standard. The color of these bricks is uniform yellow or red. It is well burnt, regular texture, uniform shape. The absorption capacity is less than 10%, crushing strength is, 280kg/cm2 (mean) where it is 245 kg/cm2 (minimum). It doesn’t have efflorescence. It emits a metallic sound when struck by another similar brick or struck by a hammer. It is hard enough to resist any fingernail expression on the brick surface if one tries to do with a thumbnail. It is free from pebbles, gravels or organic matters. It is generally used-
o in a building of long durability, say 100 years
o for building exposes to a corrosive environment;
o for making coarse aggregates of concrete.
2. Second Class Brick: The size is standard, color is uniform yellow or red. It is well burnt, slightly over burnt is acceptable. It has a regular shape; efflorescence is not appreciable. The absorption capacity is more than 10% but less than 15%. Crushing strength is 175kg/cm2(mean) where the minimum is 154 kg/cm2. It emits a metallic sound when struck by another similar brick or struck by a hammer. It is hard enough to resist any fingernail expression on the brick surface if one tries to do with a thumbnail. It is used for the construction of one-storied buildings, temporary shed when intended durability is not more than 15 years.
3. Third Class Brick: The shape and size are not regular. The color is soft and light red colored. It is under burnt, slightly over burnt is acceptable. It has extensive efflorescence. The texture is non-uniform. The absorption capacity is more than 15% but less than 20%. The crushing strength is 140kg/cm2(mean) where the minimum crushing strength is 105kg/cm2. It emits a dull or blunt sound when struck by another similar brick or struck by a hammer. It leaves fingernail expression when one tries to do with the thumbnail.
