Autoclaved aerated concrete

Autoclaved aerated concrete, or AAC, is concrete that has been manufactured to contain lots of closed air pockets. Lightweight and fairly energy efficient, it is produced by adding a foaming agent to concrete in a mould, then wire-cutting blocks or panels from the resulting ‘cake’ and ‘cooking’ them with steam (autoclaving).

In Europe AAC has a long history of development, having been in use for more than 70 years. It has a moderate embodied energy content and performs well as thermal and sound insulation, due to the aerated structure of the material and its unique combination of thermal insulation and thermal mass. It is light, does not burn, is an excellent fire barrier, and is able to support quite large loads. It is relatively easy to work with and can be cut and shaped with hand tools including woodworking tools.

AAC relatively easy to work with, and can be cut and shaped with hand tools including woodworking tools.

Blocks are made to very exacting dimensions and are usually laid in thin-bed mortar that is applied with a toothed trowel, although more conventional thick-bed mortar can be used. Wall panels are storey height, reinforced and mechanically fixed. AAC can also be used in panel form for floor and roof construction. It has a long life and does not produce toxic gases after it has been put in place.