Fly Ash Bricks – Advantages And Disadvantages

What Is Fly Ash Brick?

Fly ash bricks are unconventional bricks manufactured from industrial wastes such as fly ash, cement, sand/stone dust. These types of bricks are nowadays used worldwide with gaining popularity over clay bricks.

Advantages Of Fly Ash Bricks:

1. Appearance:

The appearance of fly ash bricks is very attractive due to their pleasing color like cement, uniform size, and smooth finish. Due to uniform size, mortar required for walls and plastering reduces almost by 40-50%.

Plaster of Paris (Gypsum plaster), putty can be applied directly without a baking coat of plaster. These bricks are free from cracks, wrap age, organic matter, pebbles, and nodules of free lime.

fly ash bricks

2. Strength:

The compressive strength of fly ash bricks is very high (9-10 N/mm2). Due to high strength no breakages/wastages during transport and handling. The lower thickness of joints and plaster reduces cracking in plaster.

These bricks do not cause any extra load for the design of structures and provide better earthquake resistance. It improves the strength over time and offers greater strength to the building.

3. Thermal Properties:

The thermal conductivity of fly ash bricks is 0.90 – 1.05 W/m2. They absorb less heat. The pozzolanic reaction between fly ash and lime produces less heat. It keeps your building cooler in summer, hence most suitable for Indian climates.

4. Durability:

These bricks are highly durable and less permeable. The lower permeability can efficiently reduce the effect of efflorescence on bricks.

These bricks are less porous, absorb less water, and reduce dampness on the walls. It is also highly resistant to attack by mild acid, water, and sulfate.

5. Sound Insulation:

Construction with these bricks provides decent sound insulation to the building.

6. Fire Resistance:

These bricks are highly fire-resistant compared to normal clay bricks.

7. Sustainability:

Fly ash bricks are environmentally friendly as they are made of waste materials that come from the combustion of coal in thermal power plants.

There is no pollution or environmental damage, considered as a white category product.

8. Buildability:

These bricks have easy workability and absorb less water. Unlike clay bricks, they do not require soaking in water for 24 hours. The sprinkling of water before use is enough.

The construction technique is same as clay brick construction and does not require any extra training for the masons.

9. Availability:

These bricks are generally available closer to the thermal power plants. However, finding dealers in all major cities and towns wouldn’t be a problem.

10. Cost:

The same number of fly ash bricks will cover more areas than clay bricks. Consumption of mortar is also low. Requires less labour. The cost is approximately 30% lower than clay bricks.

11. Applicability:

Due to its lightweight, these bricks are suitable for multi-storey structures. Less weight means less stress on the building.

These bricks can be used in load-bearing external walls in low/mid structures, non-load bearing internal walls in low/mid structures, and non-load bearing internal or external walls in highrise buildings.

Disadvantages Of Fly Ash Bricks:

1. Not all fly ash is suitable for construction, those are produced in power plants usually compatible with concrete, while others may need beneficiation.

It is very important to use only high-quality fly ash to prevent negative effects on the structure.

2. If not made properly, it has no strength and is not suitable for construction. Poor quality bricks have negative impact on concrete. It can increase permeability, resulting in damages to the structure.

3. Bonding with concrete is lower due to the smooth finish.

4. Limitation in size. Only modular size bricks can be produced. The larger size will have more breakages.

5. It is only suitable for subtropical areas, or where the climate is warm because these bricks do not absorb heat. But in winter season it is not helpful.

Fly Ash Bricks Uses:

Fly ash bricks are used in

  • Multistorey structures.
  • High-rise buildings.
  • House construction.
  • Factories.
  • Warehouses.
  • Power plants.

Fly Ash Bricks Vs Red Bricks:

Fly Ash BricksRed Bricks
These bricks are made in moulds hence are always of uniform shape.Red bricks are uneven shapes and sizes as they are hand made.
Uniform colour with pleasing appearance.Non uniform colour because the colour of these bricks depends on soil.
Plastering is not required due to smooth finish.Plastering is always required.
Lightweight.Heavier than fly ash bricks.
The compressive strength of fly ash brick is around 100 kg/cm2The compressive strength of clay brick is around 35 kg/cm2.
They can absorb more vibration than clay bricks.Cannot absorb heavy vibration.
Stronger and denser than normal red bricks.Slightly less stronger.
Less mortar requirement than clay brick constructionMortar requirement is high.
Less breakages and wastages than red clay bricks.Clay bricks are brittle material, more breakage and wastages.
Less porous, does not require soaking in water before use.Require soaking in water before use.
The cost is 30% lower than clay bricksCostly than fly ash bricks.
More environment-friendly as they are made of waste materialsNot environment friendly. But red bricks are made of clay collected from fertile land topsoil and chimney required.

So from the above comparison, it is clear that fly ash bricks have more advantages than clay bricks. You can use these bricks in any construction without any doubt.

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Also Read –

Types Of Bricks Used In Construction

How To Calculate Bricks, Cement & Sand In Brick Masonry

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