The use of bricks as a building material dates back to ancient times, and they continue to be a popular choice for constructing walls. With technological advancements and the increased availability of raw materials, a wide variety of bricks and blocks are now available in the market, which can sometimes leave buyers unsure of which one to choose for their particular project. In this article, we will provide an overview of the various types of bricks and blocks available in the Indian construction industry, including their technical specifications, advantages, and disadvantages.

CLAY Brick:

Red bricks, also known as burnt clay bricks, are a traditional type of bricks that are manufactured by molding wet clay into shape, followed by drying and firing in kilns. The bricks are graded according to their quality and strength, with high-grade bricks having fewer flaws. These bricks have the following properties:

Average strength: 30-35 kg/cm2
Water absorption: 20-25%
Density: 1600-1700 kgs/cu.m
Thermal Resistance: Low
Sound Insulation: Low
General sizes (in mm):
Length: 190/230
Height: 110
Thickness: 30/70

Red bricks have several advantages, including their wide availability throughout the country, their long history of reliable use in construction, and their versatility for aesthetic and functional purposes such as facing bricks, architectural work, exposed brickwork, and landscaping. However, they also have several disadvantages, including their contribution to erosion of topsoil and air pollution through the burning process, their uneven shape and finish, their labor-intensive production process, and the relatively high amount of waste generated on-site.

FLY ASH BRICKS:

Fly ash bricks are made by combining Fly ash, Stone Dust or Sand, Cement, and water. The mixture is then cast into molds and compacted using hydraulic press and vibration, resulting in a more precise shape and higher strength. These bricks are considered eco-friendly because they primarily use Fly ash, a byproduct from thermal power plants that is available at a low cost. The properties of Fly ash bricks are as follows:

Average strength: 50-75 kg/cm2
Water absorption: 6-12%
Density: 1500-1600 kgs/cu.m
Thermal Resistance: Moderate
Sound Insulation: Moderate
General sizes (in mm):
Length: 190/230
Height: 110
Thickness: 30/75

Fly ash bricks have several advantages, including their uniform shape and size, which reduces the need for additional cement and plastering materials. They are also environmentally friendly because they use Fly ash, a byproduct of thermal power plants that is readily available and inexpensive. In addition, they can be produced in large quantities using automatic machines. However, they also have some disadvantages, such as their smaller size (230 x 110 x 75mm), which can result in more joints in wall construction, and their smooth finish, which can reduce bonding with concrete. This can be corrected by using a cement:sand mortar of 1:4 for plastering.

CLC Light Weight Bricks:

Cellular Light Weight Concrete (CLC) Bricks, also known as Foam Concrete, are made by creating millions of bubbles in a mixture of cement, fly ash, and water using protein-based foam. These bricks can have a smooth finish produced in battery moulds or a rough finish produced by wire cutting.

Average strength: 35-50 kg/cm2
Water absorption: 6-12%
Density: 850-1000 kgs/cu.m
Thermal Resistance: High
Sound Insulation: High
General sizes (in mm):
Length: 400/600
Height: 100/150/200
Thickness: 100/150/200/225

Advantages:
Lightweight, reducing the structural load
Requires less plastering, increasing carpet area
Larger in size, reducing joint costs and enabling faster construction
Superior qualities, such as high thermal resistance, high sound insulation, and better resistance to seismic waves

Disadvantages:
Limitation in producing large quantities of bricks
Increase in strength will also increase the weight of bricks.

CONCRETE BLOCKS:

Solid Concrete Blocks are manufactured by blending Cement, Sand, Stone Chips, and water in a mixer. The wet concrete is then compacted using vibration and a hydraulic press. These blocks have multiple applications, including load-bearing and non-load bearing walls, partitions, compound walls, facing material, piers, retaining walls, garden walls, chimneys, and fireplaces.

Solid Concrete Blocks possess the following properties:

Average strength: 75-200 kg/cm2
Water absorption: 6-10%
Density: 1800-2400 kgs/cu.m
Thermal Resistance: Low
Sound Insulation: Low
General sizes (in mm): Length – 300/400, Height – 100/150/200, Thickness – 100/150/200/225 mm

The advantages of Solid Concrete Blocks include their ability to be produced at very high strength using automatic machines, making them ideal for load-bearing purposes. These blocks also have accurate dimensions and sharp edges, which enhances their versatility in various building construction and infrastructure projects.

However, Solid Concrete Blocks also have some disadvantages. They have low thermal resistance, which results in more heat being transferred indoors. Additionally, they are heavy and can be difficult to handle.

HOLLOW BLOCKS:

Hollow Blocks are made using the same raw materials and manufacturing process as Solid Concrete Blocks, but the mold has partitions to create a hollow space inside the block. These blocks have approximately 25% void in volume and are typically used for non-load bearing partition walls.

Hollow Blocks possess the following properties:

Average strength: 35-45 kg/cm2
Water absorption: 8-10%
Density: 1100-1500 kgs/cu.m
Thermal Resistance: Moderate
Sound Insulation: Moderate
General sizes (in mm): Length – 300/400, Height – 100/150/200, Thickness – 100/150/200/225 mm

The advantages of Hollow Blocks include their lightweight nature which reduces the structural load, and the use of larger size blocks reduces the number of joints in the work, thereby saving mortar. These blocks also have good insulating properties against sound, heat, and dampness.

However, Hollow Blocks also have some disadvantages. Their bearing capacity is lower than that of Solid Concrete Blocks because the total mass of wall decoration materials is reduced, thereby reducing their load-bearing capacity. It is also risky to hang heavy objects on such walls.

FAL-G Bricks:

FaL-G blocks are a mixture of Flyash, Lime, Gypsum, water, and sand (optional) that can be used as a construction material. When the mixture is hydrated, the fly ash reacts with lime at ordinary temperatures and forms a compound that has cementitious properties. The reaction between lime and fly ash produces calcium silicate hydrates, which are responsible for the development of strength in the form of bricks and blocks. Cement can also be used in the absence of lime.

These blocks possess the following properties:

Average strength: 50-100 kg/cm2
Water absorption: 8-12%
Density: 1400-1600 kgs/cu.m
Thermal Resistance: Moderate
Sound Insulation: Moderate
General sizes (in mm): Length – 300/400, Height – 100/150/200, Thickness – 100/150/200/225 mm

The advantages of FaL-G blocks include being eco-friendly, as fly-ash is the major ingredient, and using larger size blocks reduces the number of joints in the work, thereby saving mortar.

However, there are some disadvantages to using FaL-G blocks. The smooth finish of the surface can lead to difficulty in bonding with the plaster.

AAC Light Weight Bricks:

Autoclaved Aerated Concrete (AAC) bricks are a kind of lightweight bricks that are produced by combining fly-ash, gypsum, lime, cement, water, and Aluminium powder. The mixture is poured into a mold, and the aluminum powder reacts with lime and fly-ash resulting in the formation of millions of bubbles. These bubbles cause the concrete to expand, doubling its volume. After that, the aerated concrete is cut into blocks and cured for 8-12 hours using steam and pressure in autoclaves.

Average strength: 30-50 kg/cm2
Water absorption: 8-12%
Density: 650-750 kgs/cu.m
Thermal Resistance: High
Sound Insulation: High
General sizes (in mm):
Length: 400/500/600
Height: 150/200/250
Thickness: 100/150/200/225 mm

Advantages:
Reduces the dead load of the building, helping to lower project costs
Has superior heat, sound, and seismic resistance
Larger size blocks lead to faster masonry work
Due to their lightweight, the blocks can be handled easily

Disadvantages:
Requires special jointing paste and high precautions during wall construction
High water absorption can lead to cracks in the wall due to dry shrinkage
Brittle nature requires careful handling to avoid breakage
The blocks cannot be used for load-bearing, and fitting cabinets and wall hangings require longer, thinner screws.

Conclusion:

When choosing the right bricks and blocks for construction in India, there are several options available, including clay, fly ash, CLC, concrete, and hollow blocks. Each type of brick has its own set of advantages and disadvantages. Red clay bricks have a long history of reliable use in construction, but their production process is labor-intensive and contributes to environmental pollution. Fly ash bricks are Eco-friendly, uniform in shape and size, and can be produced in large quantities using automatic machines. However, they have a smaller size and smooth finish, which can reduce bonding with concrete. CLC lightweight bricks are lightweight, require less plastering, and have superior qualities such as high thermal resistance and sound insulation, but there are limitations in producing large quantities. Solid concrete blocks are ideal for load-bearing purposes, have sharp edges and accurate dimensions, but are heavy and have low thermal resistance. Hollow blocks are similar to solid concrete blocks but have a hollow space inside, reducing their weight and increasing their insulation properties. It is important to consider the specific needs and requirements of the project before choosing the right type of brick or block.