Autoclaved aerated concrete. AAC is a structural, insulating building material made of a combination of cement, lime, gypsum, and a siliceous material such as flyash from coal burning utilities. The percentage of flyash use can be as high as 75%. Therefore AAC contributes to the elimination of the flyash disposal problem. Although comparable to concrete in strength , AAC weighs approximately 75% less and can be worked like wood.
Autoclaved Aerated Concrete Exceptionally lightweight precast concrete with high thermal qualities and fire resistence. Suitable for cutting with ordinary hand tools. Mix design is composed of portland cement, sand or siliceous material, lime, gypsum, finely powdered aluminum, and water. Initial mix is a combination of portland cement, sand, lime and gypsum to produce a slurry. Finely powdered aluminum mixed into a paste is added prior to placement into large, rail-like forms. The finely powdered aluminum reacts with the alkaline components of the cement and lime to produce hydrogen gas, which increases the volume approximately five times producing a uniformly, dispersed cellular structure. Units are cut to required shape. Units are placed in an autoclave, an enclosed pressurized chamber, and steam cured at 3500 F. Approximately 80% of the ultimate volume consists of air voids.