AAC is also known as Autoclaved Aerated concrete. It is lightweight concrete. AAC Blocks have been widely using across the world. AAC Blocks are made by mixing Portland cement, lime, fly ash, water, and aluminum powder; the final mixture is poured into moulds. The reaction between aluminum and lime causes microscopic hydrogen bubbles to form lower-density concrete by expanding it. After evaporation of the hydrogen and initial setting, aerated concrete is cut into required sizes and cured by steam-curing in a pressurized chamber (an autoclave) or low pressurized steam chambers. The result is a non-toxic, high strength, lightweight, airtight material that can be used for all walling applications. AAC Blocks are green building material that generates no pollutants or hazardous waste during the manufacturing process.