There are several types of bricks used in the masonry construction based on materials such as clay, concrete, lime, fly ash, etc.
It is important to identify the filed field identification of bricks for their properties, uses and suitability for various construction works.
A brick is an important building material that is usually available in a rectangular shape made up of clay.
They are very popular from old days to modern days due to low cost and durability.
Types of Bricks used in Masonry Construction:
Based on the manufacturing process, bricks are broadly classified into two types:
Sun-Dried or Unburned Clay Bricks:
Sun-dried or unburned clay bricks are less durable, generally used for temporary structures.
The preparation of unburned bricks consists of 3 stages process and they are preparing clay, molding and drying.
After molding, the bricks are subjected to sunlight and dried using heat from the sun.
Therefore, they are not strong and has low water resistance & low fire resistance.
These bricks are not suitable for permanent structures.
Burnt Clay Bricks:
Burned bricks are good quality bricks but also contain some poor bricks, therefore burnt bricks are classified as follows:
First Class Bricks:
First class bricks are good quality bricks as compared to other classes.
They are moulded by table-moulding and lit in large kilns, so these bricks have normal dimension, sharp edges and smooth surfaces.
They are more durable and has more strength used for permanent structures, Due to their good properties, they are expensive compared to other classes.
Second Class Bricks:
The second class bricks are moderate quality bricks and molded by the process of rolling on the ground.
These bricks are also burnt in kilns however due to ground casting, they do not have smooth surfaces and sharp edges.
The shape of bricks can be irregular as a result of disparity within the ground, it will give the perfect results in strength and durability.
Smooth plastering on a brick structure is required.
Third Class Bricks:
Third Class bricks are poor quality bricks generally used for short-term constructions such as unsaturated bricks.
These bricks are not appropriate for wet areas, they are ground-type bricks and are burnt in clamps.
A lot of these bricks has a rough surface and has inappropriate edges.
Fourth Class Bricks:
Fourth class bricks are very poor quality bricks and usually are not used as bricks within the structure.
They are crushed and used as aggregates within the manufacturing of concrete and they are obtained by over burning, because of which they become hot and brittle in nature.
Therefore, they can break easily and usually are not appropriate for development purpose.
Fly Ash Bricks:
Fly ash bricks are manufactured using fly ash and water.
These bricks have higher properties than clay bricks and are very resistant to freeze-melting cycles.
These bricks have an excessive concentration of calcium oxide which is used in cement manufacturing, thus it is also known as self-cementing brick.
Fly ash bricks are lighter therefore reducing the self-weight of the structures.
The fly ash bricks have higher fire insulation, higher strength, better joints and the same size for plaster, much less water penetration, no need to be soaked before use in masonry construction.
Concrete bricks are constructed using concrete with materials such as cement, sand, coarse aggregates and water.
These bricks might be manufactured in sizes as required.
Concrete bricks are used to construct masonry and framed buildings, fences as it provides an excellent aesthetic appearance.
These bricks have a excessive compressive strength, particularly for purposes where strength, frost resistance, acid resistance and low perforation are required.
They’re generally used in basements where chemical or water attacks are the main problem for damp proof courses.
Sand Lime or Calcium Silicate Brick:
These bricks are made from sand and lime, generally known as sand-lime bricks.
These bricks are used for many purposes such as decorative work in buildings, masonry work, etc.
Properties of brick:
The following are the properties of bricks that replicate the significance of bricks in a building:
An excellent high quality brick can have resistance against abrasion.
This property known as brick hardness which helps to provide permanent nature of brick structure.
Due to this the bricks of the property do not cause damage by cracking.
Compressive strength or crushing strength is a property of brick that represents the quantity of load carried by the brick per unit area.
According to BIS, the minimal compression strength of brick needs to be 3.5N / mm2.
The crushing strength of bricks decreases when soaked in water.
Bricks usually absorb water but have limitations.
The absorption limit percentage by weight for different classes of bricks is tabulated below.
How to check quality of bricks at construction site:
- The color of the bricks should be bright and uniform.
- They should be effectively burnt and has smooth surfaces and sharp edges.
- The thermal conductivity of the bricks should be low and soundproof.
- When we put it in the water, bricks should absorb water not more than 20% by weight.
- When we hit two bricks collectively, the ringing sound has to be delivered.
- The structure of bricks should be homogeneous and uniform.
- The bricks should not break when we dropped it from the 1-meter height.
- When we scratch with a nail, there should be no scratches on the brick.
- There should be no white deposits on the brick when we soak it in water for 24 hours.
Uses different types of bricks:
- Bricks are broadly used for various functions within the construction industry.
- Good high-quality bricks (first and second class) are used within the construction of buildings, tunnels, pitching works and many others.
- Third class and unburnt bricks are used for non-permanent structures.
- Fourth class bricks are used as a combination for making concrete.
- Bricks are also used for architectural functions to offer an aesthetic appearance to the construction.
There are various types of bricks are used in construction.
Each brick are used at different stages during the erection and completion of the structure.
They are strictly used as decided by the site engineer because each has properties consistent with its purpose.