A power plant waste material called fly ash is utilised in concrete as a partial replacement for cement. In particular, masonry units that are used to erect structures are constructed using fly ash bricks as a building material. They serve as a high-quality, reasonably-priced building material.
For construction projects, fly ash bricks are utilised as an alternative to burnt clay bricks. Basic materials like fly ash, sand or stone, and regular Portland cement are used to make fly ash bricks. Compressive strength, water absorption, and efflorescence tests are among the tests done on fly ash bricks.
A fly ash brick may withstand more than 100 freeze-thaw cycles if it is compressed at a pressure of 28 MPa, cured for 24 hours in a steam bath at 66°C, and stiffened with an air-entrainment agent.
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See also: Types of bricks: Clay, concrete, fly ash bricks
The brick is considered to be “self-cementing” since class C fly ash contains a significant amount of calcium oxide. Fly ash brick production uses less energy, emits less mercury into the atmosphere, and frequently costs 20% less than traditional clay brick production. Environmentally friendly hydraulic pressure devices are used to make fly ash brick. They have a compressive strength greater than 40 Mpa and are 28% lighter than regular clay bricks. They are affordable, do not require plaster, and can save expensive building expenses and soil erosion.
Fly ash bricks: Primary constituents
The primary components of fly ash brick are fly ash, stone dust/sand, lime, gypsum and bonding agent. The mixture is carefully formulated to yield bricks with improved strength, consistency, and homogeneity.
| Raw materials | Specification |
| Fly ash | 50-70% |
| Sand | 15-20% |
| Lime and gypsum | 15-20% |
| Cement | 05-08% |
Fly ash bricks: Properties
Fly ash bricks have the following characteristics:
- Appearance: The bricks are smooth and have a suitable cement colour, so they don’t require plastering for building projects.
- Thermal conductivity: They provide intense light reflection without absorbing heat.
- Sound insulation: The level of sound insulation is sufficient.
- Resistance to fire and vermin: They have a good fire resistance and they are unaffected by vermin assaults.
- Durability and moisture absorption: These blocks have a moisture absorption rate of 6-12%, which lowers the humidity of the walls while maintaining a high level of durability.
- Toxicity and stability: Fly ash has the potential to be a useful construction material since it becomes a non-toxic product when combined with lime.
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Fly ash bricks: Advantages
The benefits of using fly ash bricks in construction include the following:
- Fly ash bricks are a lighter material than clay bricks, making them ideal for multi-story structures since less weight implies less stress on the structure, which ensures safety.
- Fly ash bricks are more suited to Indian weather since they absorb less heat than regular bricks, keeping your structure cool even in the summer.
- Less mortar is used during construction as a result of its even and consistent shape. Plastering can also be avoided if utilised for the godowns or the compound wall.
- There is no need for a background coat of plaster before applying plaster of Paris.
- Fly ash bricks have a higher compressive strength than regular bricks, resulting in less transportation waste.
- Fly ash bricks are less porous than burnt clay bricks, which means they absorb less water during building. Fly ash bricks help you save money on water during construction and even maintain the structural integrity of your structure during wet seasons.
Fly ash bricks: Drawbacks
The drawbacks of fly ash bricks include the following:
- Not all fly ash bricks are suitable for building. Some, which are often produced in power plants similarly to concrete, may require beneficiation. To minimise damaging effects on the building, it is vital to exclusively utilise high-quality fly ash.
- If bricks are not properly prepared, they lack strength and are unfit for use in construction. Concrete suffers when built with low-quality bricks. It can make a structure more permeable, leading to structural damage.
- The brick’s flat surface prevents a strong bond from forming with the concrete.
- Bricks only in modular sizes are able to be produced. More breaks will occur with larger block sizes.
- Fly ash bricks are only appropriate for subtropical regions or places with warm climates since they do not absorb heat. However, it is useless in the cold.
Fly ash bricks: Uses
- Fly ash bricks are typically utilised in load-bearing external walls of small to medium-sized buildings.
- Burnt clay bricks, one of the most essential building materials acquired for the construction of homes and structures, are often substituted by fly ash bricks. The traditional burnt clay bricks can be replaced with fly ash construction bricks in practically all situations where burnt clay bricks are ineffective for brick masonry operations.
- Bricks made from fly ash are used to create high-rise buildings, industries, warehouses, and structures with several stories.
Fly ash bricks vs red bricks
| Red bricks | Fly ash bricks |
| Not the same colour since the kind of soil and quality control used during manufacture determine the colour of the brick. | The colour of fly ash brick is comparable to bricks made under controlled settings using the equipment. |
| Since they are typically built by hand, clay bricks are not all created equally. | Due to the use of equipment in manufacture, the product is uniform in shape and has a smooth surface. |
| Plastering is required because the surface finish is not smooth or straight. | Plastering is not usually necessary because of the flat surface and thin seams. |
| The weight of clay bricks is heavier. | Fly ash is the main component of fly ash brick; hence it is lighter. |
| These bricks are less permeable than clay bricks. | Almost no pores exist in fly ash bricks. |
| Clay brick is more expensive than fly ash brick. | These bricks cost about 30% less than clay bricks. |
| Continued usage of clay bricks in the building sector will result in a significant loss of rich topsoil. | This was created utilising the leftovers from a thermal power plant which protects the ecosystem from contamination that already exists. |
FAQs
What size is a fly ash brick?
The shape of fly ash bricks is cuboidal. A cuboid has three dimensions: length, width, and height. Therefore, the fly ash brick measures 4 inches by 4 inches by 8 inches.
How much does a fly ash brick weigh?
Fly ash bricks weigh between 2-3 kg each.
How much does a fly ash brick cost?
A fly ash brick costs around Rs 6 per piece.
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Write to our Editor-in-Chief Jhumur Ghosh at jhumur.ghosh1@housing.com |