Autoclaved Aerated Concrete (AAC) has been utilized as a building material throughout the world for many years. It was developed during the early 1920s at the Technical College in Stockholm, Sweden. Since then, it has been used in the construction of commercial, industrial, institutional and residential structures throughout the world.
Autoclave Aerated Bricks is light weight building material with high insulating value which can be manufactured by using 60-75% Fly Ash by weight. Fly Ash with Carbon content up to 12% may be used in the mix there by allowing high volume use of fly ash from sources that do not meet ready mix concrete specification.
India at present produces around 120 Million Tons of Ash per annum. The power requirement of the country is rapidly increasing with increase in growth of the industrial sectors. India depends on Thermal power as its main source (around 80% of power produced is thermal power); as a result the quantity of Ash produced shall also increase. Indian coal on an average has 35 % Ash and this is one of the prime factors which shall lead to increased ash production and hence, Ash utilization problems for the country. Out of the total ash produced, Fly ash contributes to a small percentage, majority being Pond ash and bottom ash.
Autoclaved Aerated concrete (AAC), or otherwise known as Autoclave Cellular Concrete (ACC) is a lightweight, precast building material and provides structure, insulation, fire and mold resistance in a single material. AAC products include blocks, wall panels, floor and roof panels, and lintels.
It has since been refined into a high thermally insulating concrete-based material used for construction both internally and externally. Besides insulating capability, one of AAC's advantages in construction is its quick and easy installation since the material can be routed, sanded and cut to size on site using standard carbon steel band saws, hand saws and drills.
Even though regular cement mortar can be used, 98% of the buildings erected with AAC materials use thin bed mortar, which comes to deployment in a thickness of ⅛ inch. This varies on national building codes and creates solid and compact building members. AAC material can be coated with a stucco compound or plaster against the elements. Siding materials such as brick or vinyl siding can also be used to cover the outside of AAC materials.