Properties of Bricks
The required properties of good bricks are following:
A. Color: Color should be bright and uniform.
B. Shape: Bricks should have plane faces. They should have true and sharp right angled corners.
C. Size: Bricks should have standard sizes as prescribed by codes.
D. Texture: They should possess dense, fine and uniform texture. They should not possess cavities, fissures, loose grit and unburnt lime.
E. Soundness: When struck with hammer or another brick, it should generate metallic sound.
F. Hardness: Finger scratching should not produce any notion on the brick.
G. Strength: Crushing strength of brick will not be less than from3.5 N/mm2. A field test for strength is that while dropped from a height of range 0.9 m to 1.0 mm on a hard ground, the brick will not break into pieces.
H. Water Absorption: In water after immersing the brick for 24 hours, water absorption might not be more than 20 %by weight. For class-I works this restrict is 15 %.
I. Efflorescence: Bricks should not indicate white patches when soaked in water for 24 hours and then permitted to dry in shade. White patches are due to the existence of sulphate , magnesium , calcium and potassium. They keep the masonry permanently in wet and damp conditions.
J. Thermal Conductivity: Bricks should have low thermal conductivity, so that buildings construct with them are cool in summer and warm in winter.
K. Sound Insulation: Heavier bricks are poor insulators of sound whenever light weight and hollow bricks provide good sound insulation.
L. Fire Resistance: Fire resistance of bricks is generally good. In fact bricks are utilized to encase steel columns to protect them from fire.