FLY ASH BRICK

Fly ash brick are those bricks in which we used fly ash,lime or cement as raw material,by adding moderate gypsum and aggregates,after the mixture get prepared then we pressed in moulding, then through high temperature or normal pressure curing or natural curing methods.

Fly ash are divided into two categories,first one is autoclave fly ash brick and the second one is steam cured fly ash brick.In autoclaved fly ash bricks,they are cured at high temperature and pressure saturated vapors in autoclave. But in Steam cured fly ash bricks are cured in steam but under normal pressure conditions.

These both are similar in raw materials and forming,only different in curing methods,but they have very different final properties.
Autoclaved fly ash bricks are cured in saturated steam in more than 174.5˚C and 0.8Mpa pressure conditions,the inner active ingredients are reacted with each other sufficiently,thus the bricks could own high strength and stable properties.

But the steam cured fly ash brick in which the normal pressure condition will cause flaws happened on the walls during the construction.
The autoclaved fly ash brick usually have very high compressive strength, it could reach up to 15-20Mpa,at least reach 10Mpa, it can endures 15times continuous freeze-thaw cycles request.
Otherwise,fly ash is a hydrated material which has potential activity,the hydration reaction could happen again in damp environment during application,thus the inner structure of the bricks could become more and more compact,benefit for the strength improvement again.

FLY ASH BRICKS ADVANTAGES

1.Same number of Fly Ash Bricks will cover more area than clay bricks.

2. Fly Ash Bricks are High Fire Insulation.

3. Due to high strength of Fly Ash Bricks, practically no breakage occurs during transport of Fly Ash Bricks &use.

4.Due to uniform size of Fly Ash Bricks mortar required for joints and plaster requirement will be less up to 50%.

5.Lower water penetration so the seepage of water through bricks is considerably reduced.

6.In Fly Ash Bricks no need to backing coat of lime plaster, Gypsum plaster can be directly applied.

7.These Fly Ash Bricks do not require soaking in water for 24 hours. Sprinkling of water before using is sufficient.

AUTHOR:

JYOTI NARWAL

(Assistant Professor Civil Engineering Department Geeta Engineering College Panipat)