Classification Of Bricks | Bricks | Construction Materials | By Ashutosh Nautiyal

Classification Of Bricks 

Classification Of Bricks

Classification of bricks is done on various bases which are as follows:-

Based on Field Practice

First Class Bricks

• They are thoroughly burnt.

• They are of deep red, cherry or copper colour.

• They should have a uniform texture.

• They should be free from flaws, cracks and stones.

• Their surface should be smooth and rectangular.

• They should have parallel, sharp and straight edges and square corners.

• The fractured surface of the brick should not show lumps of lime.

• When the scratch is made by a fingernail, no impression should be left on the brick.

• When two first-class bricks are struck against each other, a metallic or ringing sound should be heard.

• When immersed in cold water for 24 hours, water absorption should be 12-15 % of the brick's dry weight.

• The crushing strength should not be less than 10 N/mm2. This limit varies with different Government organizations around the country.

• Uses:- In pointing, exposed face work in masonry structures, flooring and reinforced brickwork.

Second Class Bricks

• They are supposed to have the characteristics as that of first-class bricks(mentioned above)except for these three characteristics which are as follows:-

• They can have small cracks and distortion.

• They can have a higher water absorption of about 16-20% of the brick's dry weight.

• Their crushing strength should not be less than 7 N/mm2.

• Uses:- In all important or unimportant masonry works and centring of reinforced brick and reinforced cement concrete(RCC) structures.

Third Class Bricks

• They are underburnt.

• They are soft and light-coloured.

• When two third-class bricks are struck against each other, a dull sound is heard.

• They have water absorption of about 25 % of the brick's dry weight.

• Uses:- In building temporary structures.

Fourth Class Bricks

• They are overburnt.

• They are badly distorted in shape and size.

• They are brittle in nature.

• Uses:- Their ballast is used in foundation and floors in lime concrete and road metal. 

Based on Use

Common Brick 

• It is a general multi-purpose unit manufactured economically.

• It is manufactured without special reference to the appearance.

• These bricks may vary greatly in strength and durability.

• Uses:- In filling, backing and in walls where appearance is of no importance.

Facing Brick

• It has a good appearance either of colour or texture or both.

• These bricks are durable under severe exposure.

• Uses:- In fronts of building walls where appearance is of importance.

Engineering Brick

• These bricks are strong, impermeable, smooth, table moulded and hard.

• These bricks conform to defined limits of absorption and strength.

• Uses:- In all load-bearing structures.

Based on Finish 

Sand-faced Brick

• It has a textured surface manufactured by sprinkling sand on the inner surfaces of the mould.

Rustic Brick

• It has a mechanically textured finish which varies in the pattern.

Based on Manufacture 

Hand-made

• These bricks are hand moulded.

Machine-made

• Machine-made bricks are further divided into three types of bricks:-

• Wire-cut Bricks:- Bricks cut from clay extruded in a column and cut off into brick sizes by wires.

• Pressed Bricks:- Bricks are manufactured from plastic or semi-dry clay and pressed into moulds.

• Moulded Bricks:-Bricks are moulded by machines imitating hand mixing.

Based on Burning 

Pale Bricks 

• These are underburnt bricks obtained from the outer portion of the kiln.

Body Bricks 

• These are well-burnt bricks obtained from the central portion of the kiln.

Arch Bricks 

• These are overburnt bricks obtained from the inner portion of the kiln.

Based on Types 

Solid 

• These bricks can have small holes which don't exceed 25 % of the volume of the brick.

• These bricks can have frogs which don't exceed 20 % of the volume of the brick.

Perforated

• These bricks can have small holes which don't exceed 20 % of the volume of the brick.

Hollow

• These bricks can have holes(which need not be small) which exceed 25 % of the volume of the brick.

Cellular

• These bricks have holes(closed at one end) which exceed 20 % of the volume.

Based On Strength

• The Bureau of Indian Standards has classified the bricks on the basis of compressive strength which is as follows:-

 

Image From Book By S.K. Duggal

Each class of bricks mentioned above is further divided into subclasses A and B based on tolerances and shape.

Image From Book By S.K. Duggal

• Subclass-A bricks should have smooth rectangular faces with sharp corners and uniform colour.

• Subclass-B bricks can have slightly distorted and round edges.

*Self Typed

*Source- Internet, Books and Self-Analysis