What is AAC? AAC stands for Autoclaved Aerated Concrete. It is also known as Aerated Cellular Concrete or Aircrete. This precast foam concrete in the form of blocks or panels are used as wall, floor, or roofs. It is made with fine aggregates, cement, and an expansion agent that causes the fresh mixture to rise like bread dough. In the factory where it is made, the raw materials are blended, molded and cut into precisely dimensioned units. It is cured in the autoclaved and then ready for uses as building construction materials instead of bricks. Cured blocks or panels of autoclaved aerated concrete are joined with thin bed mortar as done in brick masonry work. This type of concrete contains 80 percent air. This lightweight material offers excellent sound and thermal insulation, and like all cement-based materials, is strong and fire-resistant.