Basic Concepts for Civil Engineers for Interview and Campus preparation- Bricks

Stones

• Stones are geologically classified as Ingenious, Sedimentation and Metamorphic rocks.
• Chemically they are classified as Siliceous, Argillaceous(Clay or alumina), Calcareous stones
• Physically they are classified as Stratified and Un-stratified rocks. 

Bricks
The composition of Bricks are

• Alumina 20-30%
• Silica 50-60%
• Magnesium, manganese, lime, sodium.

Excess alumina in bricks may cause cracks and warp on drying.
Excess silica in bricks may cause brittle and weak.
Excess lime causes melting and distortion during burning process of bricks.
Presence of Alkaline salts causes efflorescence in Bricks
Classification of Bricks

• First class bricks – 20% of water absorption only when bricks are immersed in water for 24 hours and compression strength of 10.5 MN/sq.m.
• Second class bricks – 22% of water absorption only when bricks are immersed in water for 24 hours.
• Third class bricks – 25% of water absorption only when bricks are immersed in water for 24 hours and not properly burnt.
• Jhuma Bricks- Over burnt, Bluish or dark colour and irregular shape.

Size

Nominal size of Bricks are 19x9x9 cms

CPWD India – 23x11.5x7.5 cms.

Notes:

• The specific Gravity of bricks is 2-2.1
• In 1 cubic metre volume around 550 bricks are used