Fly ash Bricks | An alternative Building Material
Fly ash bricks are made by compressing Class C fly ash and water at 4000psi and then curing is carried on for 24 hours at a temperature of 66 degrees Celsius steam bath. Air entrainment agent is used to toughen the bricks.
Since the concentration of calcium oxide is very high in class C fly ash, the brick is described as self cementing.
It is considered to be a good alternative to traditional mud bricks since the method of manufacture of fly ash is energy efficient that is it helps save energy, brings about reduction of mercury pollution and plus it is cost effective.
Raw materials used for the manufacture of Fly ash Bricks:
- Fly ash – which is the primary ingredient
- Sand or Stone dust – as fine aggregate
- Lime – source of calcium carbonate which results in the bricks being called “Self-cementing bricks”.
- Gypsum – to enhance the fineness of the shape of the bricks
- Cement – to increase bonding and strength
General Characteristics of Fly ash Bricks
- The standard size of the brick is 230x110x70
- The bricks are manufactured and tested as per IS 12894-2002
- Fly ash bricks are sound, compact and uniform in shape, size and colour. Smooth rectangular faces of the bricks are accompanied with sharp and square corners.
- They are free from visible cracks, warpage, flaws and organic matter.
- Compressive strength: 7.5N/mm2 on an average
- Water absorption: <8%
Advantages of Fly ash Bricks
- They have high strength which is their primary benefit to be used for construction.
- Due to uniform size and thickness of joints, plaster consumption is minimized compared to clay bricks, thereby saving cement to the extent of 25% to 30%.
- Due to lesser water absorption, there is no dampness in walls.
- Gypsum plaster, Plaster of Paris can be applied directly without the basecoat of plaster.
- Wastage is very less as compared to clay brick.
- The bonding between the bricks is excellent since there is high concentration of calcium oxide in it.
Uses of Fly ash Bricks
Fly ash bricks are used for the construction of various types of buildings such as:
- Power plants
- High rise structures
Basically, they are used in every kind of construction that can be possibly executed with the help of traditional bricks.
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