AAC is made with cement, lime, water and sand. The sand is ground to a fine powder. A small amount of aluminium paste is added to the mixture. This reacts with the alkaline elements in the cement and lime causing the mixture to aerate, filling with millions if tiny finely dispersed bubbles.
When the concrete is partially cured, it is stripped from the mould, cut into blocks or panels and steam cured in an autoclave under high pressure and temperature. The result is a concrete that’s only about one fifth of the weight of conventional concrete.
Autoclaved aerated concrete was invented in Sweden in the 1920’s and Josef Hebel began commercial production in Germany in the 1940. Architects, engineers and builders quickly saw the benefits of a building material that has the density and workability of timber yet without the problems of decay, shrinkage, warping and flammability.