1. Fly ash 60%
2. Sand / Stone dust 30%
3. Ordinary Portland cement/(Lime + Gypsum) 10%
The total formula of material 100%
The strength of fly ash brick produced with the above configurations ranges between 7.5 MPa and 10 MPa. The Fly ash bricks are tougher and lighter than clay bricks.
The fly ash bricks have main ingredients such as fly ash, water, quicklime or lime sludge, cement, aluminum powder, and gypsum. Auto craving raises the hardness of the block by stimulating quick curing of the cement. Gypsum conducts as a long-term strength gainer.
Utilizing the fly ash bricks in the buildings decreases the dead load, permitting one to save around 30 to 35% of structural steel, and concrete.
Commercial processes fall into two sectors; the lime route, and the cement (Ordinary Portland Cement) path where the latter is utilized as a source of lime.
In the lime path, the configuration is fly ash (50%), slaked lime (30%), and anhydrous gypsum (20%), to which 3 to 4 times of stone dust, sand, or any inert filling material can be added. In the cement route, the composition is fly ash (76%), Ordinary Portland cement (20%), and anhydrite (4%), to which 3 to 4 times of filling material can be added.