Introduction of Bricks In Construction
The bricks are obtained by moulding clay in rectangular blocks of uniform size and then by drying and burning these blocks.
Bricks are one of the oldest building material and it is extensively used at present for loading the material in construction methods because of their durability, strength, reliability, low cost, easy availability, etc.
Bricks are used for building up exterior and interior walls, partitions, piers, footings, and other loading structures.
Size and Weight of Brick In India
Bricks Dimension or Size of brick
- The standard size of bricks is 19 cm x 9 cm x 9 cm.
- Nominal size (with mortar) is 20 cm x 10 cm x 10 cm.
- The commonly adopted nominal size of traditional bricks is 23 cm x 11.4 cm x 7.8 cm.
Weight of Brick
- It is found that the weight of 1 m³ of brick earth is about 1800 kg. Hence the average weight of a brick is about 3 to 3.5 kg.
Classification of Bricks or Bricks Types
(A) On Field Practice
Clay bricks are classified as first class, second class, third class, and fourth class based on their physical and mechanical properties.
First class bricks
- These bricks are table-moulded and of standard shape and they are burnt in kilns.
- The surfaces and edges of the bricks are sharp, square, smooth, and straight.
- First-class bricks have all qualities of good bricks.
- These bricks are used for superior work of permanent nature
- Compressive strength> 10.5 N/mm²
- On allowing immersed in cold water for 24 hours, water absorption should not be more than 20% of its dry weight.
Uses: First-class bricks are recommended for pointing, exposed facework in masonry structures, flooring, and reinforced brickwork.
Second class brick
- These bricks are ground moulded and they are burnt in kilns.
- The surface of these bricks is somewhat rough and the shape is also slightly irregular.
- These bricks are commonly used at places where brickwork is to be provided with a coat of plaster.
- Water absorption of 22% of its dry weight is allowed.
- Compressive strength ≥ 7.0 N/mm².
Uses: Second-class bricks are recommended for all important or unimportant hidden masonry works and centering of reinforced brick and reinforced cement concrete (RCC) structures.
Third class bricks
- These are ground moulded and they are burnt in clamps.
- These bricks are not hard and they have a rough surface
- These bricks give a dull sound when struck together.
- They are used for unimportant and temporary structures.
- Water absorption is about 25% of its dry weight is allowed.
- These have rough surfaces with irregular or distorted edges.
Uses: For unimportant and temporary structures and at places where rainfall is not heavy.
Fourth class bricks
- These are over-burnt bricks with irregular shapes and dark colors. These bricks are used as aggregate for concrete in foundations, floors, roads, etc. because of the fact that the over-burnt bricks have a compact structure, and hence they are sometimes found to be stronger than even the first class bricks.
Uses: Used as ballast in foundations, and floors in lime concrete.
NOTE: Heavy-duty bricks have a compressive strength of more than 40 N/mm2, used in structures such as bridges, foundation buildings, etc. water absorption is limited to 5%.
(B) On Strength
- Bureau of Indian Standards, (BIS) has classified the bricks on the basis of compressive strength and given as:
|Average compressive strength
not less than (N/mm²)
- As per IS 1077-1976, common building bricks shall have a minimum strength of 35 kgf/cm² or (3.5 N/mm²).