The advantages of using fly ash brick are, the bricks carries good compressive strength, provide better thermal insulation than red clay bricks, cheaper compared to clay bricks and are environment friendly That is the sole reason we discontinued use of these bricks.Fly ash brick (FAB) is a building material, specifically masonry units, containing class C or class F fly ash and water. Compressed at 28 MPa (272 atm) and cured for 24 hours in a 66 °C steam bath, then toughened with an air entrainment agent, the bricks last for more than 100 freeze-thaw cycles.Fly ash is used as a supplementary cementitious material (SCM) in the production of portland cement concrete. A supplementary cementitious material, when used in conjunction with portland cement, contributes to the properties of the hardened concrete through hydraulic or pozzolanic activity, or both.Coal fly ash are lightweight particles captured in exhaust gas by electrostatic precipitators and bag houses of coal-fired power plants. Fly ash is very fine with cement like properties and has long been used as an additive in cement, though not without some controversy.The reduction in water leads to improved strength. Because some fly ash contains larger or less reactive particles than portland cement, significant hydration can continue for six months or longer, leading to much higher ultimate strength than concrete without fly ash.An ash pond is an engineered structure for the disposal of bottom ash and fly ash. The wet disposal of ash into ash ponds is the most common ash disposal method, but other methods include dry disposal in landfills. Dry-handled ash is often recycled into useful building materials.Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys. One of the most beneficial uses for silica fume is in concrete. Because of its chemical and physical properties, it is a very reactive pozzolan. Concrete containing silica fume can have very high strength and can be very durable.