Characteristics of good bricks

While selecting bricks for important engineering works following qualities are considered necessary:
1. Appearance:
 It should be rad in color, regular rectangular faces with sharp and well-defined edges. A good brick should be free from all flaws such as cracks, grits, and nodules of lime, etc.
2.Strength:
  It should be strong enough to take the loads coming over it. Generally, a good brick should not brick when made to fall on another brick from a height of 1.25 m.
3.Soundness:
  When two bricks are struck together it should give a metallic ringing sound.
4.Hardness:
   A good brick should be sufficient hard. When scratched with a thumb-nail, no mark should be left on the surface of the brick.
5.Durability:
   It should be durable enough to stand the weather effects like rains, temperature variations, and frost action, etc.















6.Structure:
   It should have a uniform compact and fine structure when broken.
7. Porosity:
    It should be less porous and should not absorb more than 20% of water by weight when immersed in water for 24 hours.
8.Efflorescence:
   Alkaline salts should be minimum possible in a good brick which may cause decay of the bricks.
9.Resistance to fire:
   A good brick should also have enough resistance to fire. Ordinarily, a good brick can resist temperature up to 1200°c. But in case of the lining of furnaces fire brick are used.