Difference Between Red Bricks And Fly Ash Bricks

1- Fly Ash bricks are cast in molds hence are always of uniform shape. Clay bricks are handmade causing a slight difference in their shape and size.

2- Clay bricks are more porous than Fly ash bricks.

3- Fly ash bricks are lighter in weight and less costly than Clay bricks.

4- Fly ash bricks are made of waste materials that come from the combustion of coal in thermal power plants. Clay bricks are made of clay which is collected from fertile land or the topsoil. This is the prime reason that makes Fly ash bricks more preferable to Clay bricks.

5- In all aspects fly ash bricks are better than clay bricks. They are environment-friendly because the maximum constituent is ash and fly ash bricks have greater strength as compared to red bricks.

Fly Ash Bricks Advantage
1- Due to perfect size savings in cement mortar for making
the walls and plastering by 20-40%
2- The strength of supplied lot is similar.
3- Plaster of Paris, Putty can be applied directly without a
backing coat of plaster.
4- Lower water penetration to Clay Bricks.
5- High Strength-can is used for load-bearing walls.
6- Eco-friendly using Fly Ash.

Fly Ash bricks Disadvantage
1- Bonding is lower due to smooth finish, this can be easily
corrected by using a cement: sand mortar of 1:4 and proper
curing. Also, the quality of the sand needs to be checked.

Clay Bricks Advantage

1- clay brick at high temperatures is weakly acidic, alkaline slag erosion resistance to a bit weak, but with Al2O3 content increased and enhanced. Thermal stability than the refractory brick, magnesia brick as well.
2- After the blast of acceptable quality clay dried vacuum impregnation process phosphoric acid, phosphoric acid impregnated low-temperature firing of secondary products, it can be used for masonry lining blast furnace body portion.
3- Brick from local materials, cheap, durable, as well as fire protection, thermal insulation, sound insulation, moisture absorption, etc., used in a wide range of engineering works. Waste and scrap refractory bricks can be made of concrete aggregate.

Clay Bricks Disadvantage
1- Uneven shape
2- Labour Intensive.
3- Inefficient Kilns Coal Fired -Pollution
4- Cutting of agricultural land and hills -Pollution and
against world food security.

Comparison of Red Bricks and Fly Ash Bricks

Properties	Red Bricks/Clay Bricks	Fly Ash Bricks	Remarks
Density	1600-1750 kg/m³	1700-1850 kg/m³	Higher load-bearing
Compressive strength	30-35 kg/cm²	90-100 kg/cm²	Higher load-bearing
Absorption	15-25%	10-14%	Less dampness
Dimensional stability	Very low tolerance	High tolerance	Saving in mortar up to 25%
Wastage during transit	Up to 10%	Less than 2%	Saving in cost up to 8%
Plastering	Thickness varies on both sides of the wall	Even on both sides	Saving in plaster up to 15%.