Bricks

 One of the oldest building material brick continues to be the most popular and leading construction material because of being cheap, durable and easy to handle and work with. Clay bricks are used for building-up exterior and interior walls, partitions, piers, footings, pavement and other load-bearing structures.

A brick is rectangular in shape and of the size that can be conveniently handled with one hand. Brick may be made of burnt clay or mixture of sand and lime or of Portland cement concrete. Clay bricks are commonly used since these are economical and easily available.

clay is plastic earth, is constituted largely of sand an alumina and may contain various quantities of chalk, iron oxide, magnesia, alumina etc.

Brick plays a very important role in the field of civil engineering construction. Bricks are used as an alternative of stones in construction purpose. Here some main uses of construction brick are given below.

  • Construction of walls of any size
  • Construction of floors
  • Construction of arches and cornices
  • Construction of brick retaining wall
  • Making Khoa (Broken bricks of required size) use as an aggregate in concrete
  • Manufacture of surki (powdered bricks) to be used in lime plaster and lime concrete.
Characteristics of good bricks

It is always desirable to use the best quality brick in constructions. Therefore, the Characteristics of a good brick must be investigated. Generally, good bricks possess the following properties-

  • Bricks should be uniform in colour, size and shape. The standard size of brick should be maintained.
  • They should be sound and compact.
  • They should be free from cracks and other flaws such as air bubbles, stone nodules etc. with sharp and square edges.
  • Bricks should be table moulded, well burnt in kilns, Copper coloured free from cracks.
  • Bricks should give clear ringing when it struck with each other.
  • Bricks, when broken, should show a bright homogeneous and compact structure free from voids.
  • Bricks should not absorb more than 20% of their own weight of water when immersed in water for 24 hours (15% to 20% of dry weight).
  • Bricks should be sufficiently hard. No impression should be left on the brick surface when it is scratched with the finger nail.
  • Bricks should not break when dropped flat on the hard ground from a height of about one meter.
  • The compressive strength of bricks should be in the range of 15 to 35 MPa.
  • Salt attack hampers the durability of brick. The presence of excess soluble salts in brick also causes efflorescence. The percentage of soluble salts (sulphates of calcium, magnesium, sodium and potassium) should not exceed 2.5% in brunt bricks.
  • Bricks when soaked in water for 24 hr. should not show a deposit of white salt when allowed to dry in shade.
  • Brick should not change in volume when wetted.
  • Bricks should neither overburnt nor under-brunt.
  • The thermal conductivity of bricks should be low as it is desirable that the building built with them should be cool in summer and warm in winter.
  • Bricks should be soundproof.
  • Bricks should be non-inflammable and incombustible.
  • Bricks should be free from lime pitting.


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