CLASSIFICATION OF BRICKS

On the basis of field practice.

• Clay bricks are classified as.

• first class,

• second class,

• third class,

• fourth class.

First class bricks. 

1. These are thoroughly burnt and are of deep red, cherry or copper colour.

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. Water absorption should be 12–15% of its dry weight when immersed in cold water for 24 hours.

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

Second class bricks.

1. They are supposed to have the same requirements as the first class

ones except that.

2. Small cracks and distortions are permitted.

3. A little higher water absorption of about 16–20% of its dry weight

is allowed.

4. The crushing strength should not be less than 7.0 N/mm2.

5. Uses: Second class bricks are recommended for all important or

unimportant hidden masonry works.

Third class bricks.

• They are underburnt.

• They are soft and light-coloured.

• They are 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.

Fourth class bricks.

• They are overburnt.

• The are badly distorted in shape and size.

• They are brittle in nature.

• Uses: The ballast of such bricks is used for foundation and floors in

lime concrete and road metal.

On the basis of use bricks are classified into 3

types.

• Common bricks is a general multi

-purpose unit manufactured,

economically without special reference to appearance.

• Facing Bricks are made primarily with a view to have good

appearance, either of colour or texture or both.

• Engineering Bricks are strong, impermeable, smooth, table moulded,

hard and conform to defined limits of absorption and strength.

On the basis of finish, bricks classified into 2

types.

• Sand

– faced brick

- has textured surface manufactured by sprinkling

sand on the inner surfaces of the mould.

• Rustic bricks

- has mechanically textured finish, varying in pattern.

On the basis of burning it is classified into 3

types.

• Pale bricks are underburnt bricks obtained from outer portion of the

kiln.

• Body bricks are well burnt bricks occupying central portion of the kiln.

• Arch bricks are overburnt also known as  clinker bricks obtained from

inner portion of the kiln.