Aerated concrete is produced by the incorporation of a gas or air in a base mortar mix, it is categorised in two groups.

­Gas formed within the mass of the fresh mortar by means of a chemical reaction. These units are factory manufactured in steel moulds and autoclaved. They can be reinforced and have high thermal insulation properties. Block types include Thermalite and Celcon.

­Foamed concrete is where air is introduced to the base mix by an addition of a preformed foam. Excellent as a trench fill material, it is generally unreinforced and air cured.