Bricks are one of the most commonly used building materials in construction. They are made from clay or a mixture of clay and other materials, which are then fired in a kiln to create a solid, durable structure.
Bricks can be classified into different categories based on their quality, strength, size, and purpose. The four main classes of bricks are first-class, second-class, third-class, and fourth-class bricks.
Classification of bricks
- First class Bricks
- Second class Bricks
- Third class Bricks
- Fourth class Bricks
These classes of bricks are based on the uniformity of their size, shape, color, and strength, and are used for different purposes in construction.
First class bricks
First-class bricks are high-quality, uniform, and well-burnt bricks that are commonly used for construction purposes. They are made from high-quality clay and are molded under pressure to achieve a uniform size and shape.
The dimensions of first-class bricks are usually 190mm x 90mm x 90mm (7.5 inches x 3.5 inches x 3.5 inches), with a tolerance of ±3 mm.
They are uniform in shape and color and have smooth surfaces with sharp edges and corners.
First-class bricks have a compressive strength of at least 10.5 N/mm² and an absorption capacity of less than 15% of their dry weight.
They are durable, long-lasting, and resistant to weathering, and are therefore commonly used in building foundations, walls, and other load-bearing structures.
Second class bricks
Second-class bricks are lower-quality bricks that are commonly used for non-load-bearing walls, garden walls, and other similar purposes.
They are made from a mix of clay, sand, and other materials, and are usually less uniform in size, shape, and color than first-class bricks.
The dimensions of second-class bricks may vary more widely than first-class bricks, but they are typically similar in size, ranging from 190mm x 90mm x 90mm (7.5 inches x 3.5 inches x 3.5 inches) to 230mm x 110mm x 70mm (9 inches x 4.3 inches x 2.8 inches).
Second-class bricks have a lower compressive strength than first-class bricks, typically ranging from 3.5 N/mm² to 7.5 N/mm², and have a higher absorption capacity, typically ranging from 15% to 20% of their dry weight.
Third class bricks
Third class bricks, also known as “kachi” bricks, are the lowest quality bricks and are not suitable for use in construction projects where structural strength is required.
They are made from a mixture of clay, sand, and other materials, and are often made using traditional methods that do not involve firing in a kiln.
The dimensions of third-class bricks may vary widely, and they are usually irregular in shape and size.
They are typically smaller than first and second-class bricks and are often used for decorative purposes such as garden walls or pathways.
Third-class bricks have a low compressive strength, typically less than 2.5 N/mm², and a high absorption capacity, often exceeding 20% of their dry weight.
They are not very durable and can easily be damaged by weathering or impact.
Fourth class bricks
Fourth-class bricks are not commonly used for construction purposes and are often referred to as “reject” bricks.
They are the lowest quality bricks and are generally made from unsuitable soil or clay that does not meet the requirements for making first, second, or third-class bricks.
The dimensions of fourth-class bricks may vary widely, and they are often irregular in shape and size.
They are not uniform in color, texture, or strength and are usually discarded or used for non-structural purposes.
Fourth-class bricks have a very low compressive strength, often less than 1.5 N/mm², and a high absorption capacity, often exceeding 25% of their dry weight.
They are not durable and can easily be damaged by weathering, impact, or moisture.
A quick comparison between first-class, second-class, third-class, and fourth-class bricks
| Type of brick | Uses | Size | Compressive Strength | Absorption Capacity |
| First-class | Load-bearing structures, foundations, walls | 190mm x 90mm x 90mm (7.5″ x 3.5″ x 3.5″) | 10.5 N/mm² or higher | Less than 15% of dry weight |
| Second-class | Non-load bearing walls, garden walls | 190mm x 90mm x 90mm (7.5″ x 3.5″ x 3.5″) to 230mm x 110mm x 70mm (9″ x 4.3″ x 2.8″) | 3.5 N/mm² to 7.5 N/mm² | 15% to 20% of dry weight |
| Third-class | For decorative purposes, non-structural walls | Varies widely | Less than 2.5 N/mm² | Exceeding 20% of dry weight |
| Fourth-class | Non-structural purposes such as filling or leveling | Varies widely | Less than 1.5 N/mm² | Exceeding 25% of dry weight |
FAQ
What is the difference between first-class and second-class bricks?
First-class bricks have a higher compressive strength and lower absorption capacity than second-class bricks. They are suitable for load-bearing structures, while second-class bricks are used for non-load-bearing walls and garden walls.
Can third-class bricks be used for load-bearing structures?
No, third-class bricks are not suitable for load-bearing structures due to their low compressive strength and high absorption capacity.
How do I determine the quality of a brick?
The quality of a brick can be determined by its compressive strength, absorption capacity, and durability. The size and shape of the brick can also affect its quality.
Are all bricks the same size?
No, different classes of bricks can have different sizes and shapes. First-class and second-class bricks are typically uniform in size, while third-class and fourth-class bricks can vary widely in size and shape.
Can I use first-class bricks for non-load-bearing walls?
Yes, first-class bricks can be used for non-load-bearing walls, but they are more expensive than second-class bricks and may not be cost-effective for this purpose.
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