Brick Classification: Types, Uses, and Properties

What Is Classification of Bricks?

Many types of brick available in the market. All bricks are a different purpose and different place used, so us classification bricks as below. Bricks are classified in two ways, traditionally or according to the IS classification system.

Traditionally there are four classes – first, second, third, and kiln rejected. First class bricks are well burnt with an even surface and ringing sound, water absorption under 20%, and compressive strength over 10.5 N/mm2.

Classification of Bricks

Based on Shape
Based on Quality
Based on Their Using
Based on Raw Materials
Based on Building Process
Based on Manufacturing Method
Bricks Based on Weather-resisting Capability

#1. Classification of Bricks:Based on Shape

Squint Brick.
Splay Brick.
Coping Bricks.
Bull-Nose Bricks.
Cownose Brick.
Perforated Bricks.
Hollow Bricks.

1. Squint Brick:

They are cut at a corner at an angle of more than 90 degrees. They are required to shape the outer or inner corner in a wall.

2. Splay Brick:

They have a level or part, width-wise, length, or in both directions. The individual shapes are grouped under gleaming bricks, which are also made for use indoors and windows, vents, and plinths.

3. Coping Bricks:

They are used for coping on the walls to give them a good appearance and can also be used for easy drainage of water. When a coping is to be provided to a wall, a particular shape may be desired. Chuffed, half-round, and saddleback bricks are some common imitating bricks.

4. Bull-Nose Bricks:

These bricks have rounded corners and are usually preferred in buildings from an architectural point of view. They are mostly used in the construction of steps, sills, and capping walls. It is a standard brick with one edge rounded.

5. Cownose Brick:

It is similar to the bullnose, but it has both sides rounded to one side. It can also be called double bullnose bricks. They have the same use as bullnose, but they only give additional roundness.

6. Perforated Bricks:

These bricks have hollow holes, produced by pushing iron bars within the bricks. The purpose of producing these holes is to reduce the overall weight of the brick, thus minimizing the self-weight of the structure. However, these bricks do transmit sound and are also not suitable to be used in the hydraulic structures.

7. Hollow Bricks:

These bricks are used for insulation purposes. They are strong against distributed loads; however, they may easily fail against concentrated loads. They are different from perforated brick as a number of holes in the hollow brick are less, but the size of holes is bigger as compared to those in perforated bricks.

#2. Classification of Bricks: Based on Quality

First Class Bricks.
Second Class Bricks.
Third Class Bricks.
Fourth Class Bricks.

1. First Class Bricks:

These are the high-quality bricks, having a uniform shape. Color and texture. They have sharp edges. They are sound and well burnt. If scratched with a nail, they leave no mark. Moreover, if struck against each other, a clear metallic sound is produced. They are free from efflorescence, cracks, and other flaws. The crushing strength of these bricks is approximately 105 kg/cm².

The water absorption after 24 hours in the water is no more than 10- 15 percent by mass of the brick. Owing to the highest quality, they are used in load-bearing walls and pavements.

2. Second Class Bricks:

Although sound and well burnt, the second class bricks have certain irregularities in shape and texture. Like first class bricks, they are also free from cracks, considerable efflorescence, and flaws.

The water absorption after 24 hours in the water is about 20 percent by mass of the brick. They are also used in load-bearing walls but of moderate capacity, usually in single-story buildings. However, they are widely used in partition walls. Moreover, they are preferred as brick ballast in foundations and floorings.

3. Third Class Bricks:

Slightly under burnt bricks are termed as third-class They are not uniform in shape and size. Their crushing strength is about 30 kg/cm²far below than that of first-class bricks.

The water absorption is about 25 percent by mass of the brick after 24 hours of submersion in water. They produce a dull sound when struck against each other. Though they have poor strength and texture, yet they are highly economical and can be used in the construction of temporary and rural structures.

4. Fourth Class Bricks:

They are slightly over burnt thus have very low strength and are not recommended for application in major construction works. However. They can be used in flooring, and inferior construction works.

#3. Classification of Bricks: Based on Their Using

Common Bricks.
Engineering Bricks.

1. Common Bricks:

These bricks are the most common bricks used. They don’t have any special features or requirements. They have low resistance, low quality, low compressive strength. They are usually used on the interior walls.

2. Engineering Bricks:

Engineering bricks are bricks manufactured at extremely high temperatures, forming a dense and strong brick, allowing the brick to limit strength and water absorption. Engineering bricks offer excellent load bearing capacity damp-proof characteristics and chemical resisting properties.

#4. Classification of Bricks: Based on Raw Materials

Common Burnt Clay Bricks.
Sand Lime Bricks.
Fly Ash Clay Bricks.
Concrete Bricks.
Firebrick.

1. Common Burnt Clay Bricks :

Common burnt clay bricks are formed by pressing in molds. Then these bricks are dried and fired in a kiln. Common burnt clay bricks are used in general work with no special attractive appearances. When these bricks are used in walls, they require plastering or rendering.

2. Sand Lime Bricks :

Sand-lime bricks are made by mixing sand, fly ash and lime followed by a chemical process during wet mixing. The mix is then molded under pressure forming the brick. These bricks can offer advantages over clay bricks such as their color appearance is grey instead of the regular reddish color.

Their shape is uniform and presents a smoother finish that doesn’t require plastering. These bricks offer excellent strength as a load-bearing member.

3. Fly Ash Clay Bricks:

Fly ash clay bricks are manufactured with clay and fly ash, at about 1,000 degrees C. Some studies have shown that these bricks tend to fail poor produce pop-outs, when bricks come into contact with moisture and water, causing the bricks to expand.

4. Concrete Bricks:

It is made of concrete. It is the least used bricks. It has low compression strength and is of low quality. These bricks are used above and below the damp proof course.

These bricks are used can be used for facades, fences, and internal brick-works because of their sound reductions and heat resistance qualities. It is also called mortar brick. It can be of different colors if the pigment is added during manufacturing. It should not be used below ground.

5. Firebrick:

It is also known as refractory bricks. It is manufactured from a specially designed earth. After burning, it can withstand very high temperatures without affecting its shape, size, and strength. It is used for the lining of chimney and furnaces where the usual temperature is expected to be very high.

#5. Classification of Bricks: Based on Building Process

Unburnt Bricks.
Burnt Bricks.

1. Unburnt Bricks:

Unburn or sun-dried with the help of heat received from the sun after the process of molding. These bricks can only be used in the construction of temporary and cheap structures. Such bricks should not be used in places exposed to heavy rains.

2. Burnt Bricks:

Burnt bricks are made by burning them in the kiln. First-class, Second Class, Third Class bricks are burnt bricks.

#6. Classification of Bricks: Based on Manufacturing Method

Ground-Moulded Bricks.
Table-Moulded Bricks.
Machine-Moulded Bricks

1. Ground-Molded Bricks :

The ground is first made level and fine sand is sprinkled over it. Mould is dipped in water and placed over the ground to fill the clay. Extra clay is removed by wooden or metal strike after the mold is filled forced mold is then lifted up and raw brick is left on the ground.

Mould is then dipped in water every time lower faces of ground molded bricks are rough and it is not possible to place the frog on such bricks. Ground molded bricks of better quality and with frogs on their surface are made by using a pair of pallet boards and a wooden block.

2. Table-Molded Bricks:

Molding is done on a table of size lm x 2m with the help of hands, molds and various tools.

3. Machine-Moulded Bricks:

The molding of bricks is carried out with the help of a machine. This method results in better shape and a high production rate. This approach is used when a larger number of bricks are required in a very limited time span.

#7. Classification of Bricks: Based on Weather-Resisting Capability

No Weather Grade.
Moderate Weather Grade.
Severe Weather Grade.

1. No Weather Grade:

These bricks do not have any weather resisting capabilities and used on the inside walls.

2. Moderate Weather Grade:

These types of bricks are used in tropical countries. They can withstand any high temperature.

3. Severe Weather Grade:

These types of bricks are used in the countries which are covered in snow most of the time of year. These bricks are resistant to any kind of freeze-thaw actions.

Frequently Asked Questions (Faqs) You Can Include in Your Article on Brick Classification:

What Are the Different Types of Bricks Based on Their Shape?

Squint Brick, Splay Brick, Coping Bricks, Bull-Nose Bricks, Cownose Brick, Perforated Bricks, Hollow Bricks.

How Are Bricks Classified Based on Quality?

First Class Bricks, Second Class Bricks, Third Class Bricks, Fourth Class Bricks.

What Are Common Uses of Different Classes of Bricks?

First Class Bricks: Used in load-bearing walls and pavements.
Second Class Bricks: Used in single-story buildings, partition walls, and foundations.
Third Class Bricks: Used in temporary and rural structures.
Fourth Class Bricks: Used in flooring and inferior construction works.

What Are Engineering Bricks, and Where Are They Used?

Engineering bricks are high-strength bricks used for load-bearing purposes, offering excellent damp-proof and chemical-resisting properties. They are used in areas requiring high durability and strength.

How Are Bricks Classified Based on Raw Materials?

Common Burnt Clay Bricks, Sand Lime Bricks, Fly Ash Clay Bricks, Concrete Bricks, Firebricks.

What Is the Difference Between Burnt and Unburnt Bricks?

Burnt bricks are fired in a kiln, offering higher strength and durability suitable for permanent structures. Unburnt bricks are sun-dried and used in temporary constructions due to their lower durability.

What Are the Advantages of Machine-Moulded Bricks Over Ground-Moulded Bricks?

Machine-moulded bricks have better shape consistency and a higher production rate compared to ground-moulded bricks, which are hand-moulded.

Which Types of Bricks Are Suitable for Severe Weather Conditions?

Bricks classified as Severe Weather Grade are suitable for regions with extreme weather conditions such as heavy rains or snow.

What Are the Properties of Firebricks, and Where Are They Used?

Firebricks, or refractory bricks, can withstand very high temperatures without losing their shape or strength. They are used in lining chimneys and furnaces.

How Can One Identify First-Class Bricks Based on Their Characteristics?

First-class bricks are well burnt with sharp edges, uniform color, and texture. They produce a clear metallic sound when struck and have low water absorption and high compressive strength.