BRICKS

COMPOSITION OF BRICK

1. SILICA -50 to 60% 

• Prevents shrinking, cracking and warping
• Impart uniform shape
• Makes the brick durable and heat resistant
• Excess silica results in making the brick brittle and weak

 2. ALUMINA -20 to 30%

• Chief ingredient
• Impart plasticity for easy molding
• Excess alumina results in making the brick shrink and wrap during drying and molding

3. LIME - up to 5%

• Prevents shrinkage of row brick
• Excess lime results in making the brick to melt and distort

4. IRON OXIDE - 5 to 6%

• Imparts red color to bricks
• Excess iron oxide results in making the brick blue or blackish
• Less iron oxide results in making the brick yellowish in color

5. MAGNESIA - small quantity

• Imparts yellow color to bricks
• Decrease shrinkage
• Excess magnesia results in decaying of brick

HARMFUL INGREDIENTS

1. ALKALIES

• It absorb moisture from air and form white crystalline substance called efflorescence

2. IRON PYRITES

3. PEBBLES

4. VEGETATION AND ORGANIC MATTER