Brick is one of the oldest building material that continues to be a most popular and leading construction material because of being cheap, durable and easy to handle and work with. Fly Ash & Clay bricks are used for building-up exterior and interior walls, partitions, piers, footings and other load bearing structures.

Shape of a brick is rectangular and its size 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.

Dimensions of a brick are interrelated as below:

Length of brick = 2 × width of brick + thickness of mortar

Height of brick = width of brick

Size of a standard brick (also known as modular brick) should be 19 × 9 × 9 cm and 19 × 9 × 4 cm.

When placed in masonry the 19 × 9 × 9 cm brick with mortar becomes 20 × 10 × 10 cm.

Classification of Bricks
On Filed 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

1. These are thoroughly burnt.
2. The surface should be smooth and rectangular, with parallel, sharp and straight edges and square corners.
3. These should be free from flaws, cracks and stones.
4. These should have uniform texture.
5. No impression should be left on the brick when a scratch is made by a finger nail.
6. The fractured surface of the brick should not show lumps of lime.
7. A metallic or ringing sound should come when two bricks are struck against each other.
8. When immersed in water, water-absorption should be less than 20%.
9. The crushing strength of the brick should not be less than 10 N/mm2. This limit varies with different Government organizations around the country. Uses: First class bricks are recommended for pointing, exposed face work in masonry structures, flooring and reinforced brick work.

Second Class Bricks are supposed to have the same requirements as the first class ones except that
1. Small cracks and distortions are permitted.
2. A little higher water absorption of about 16–20% of its dry weight is allowed.
3. The crushing strength should not be less than 7.0 N/mm2.
Uses: Second class bricks are recommended for all important or unimportant hidden masonry works and cantering of reinforced brick and reinforced cement concrete (RCC) structures.

Second Class Bricks are under burnt. They are soft and light-coloured producing a dull sound when struck against each other. Water absorption is about 25 per cent of dry weight.
Uses : It is used for building temporary structures.

Third Class Bricks are over burnt and badly distorted in shape and size and are brittle in nature.

Uses: The ballast of such bricks is used for foundation and floors in lime concrete and road metal.

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