101 Basics of Autoclaved Aerated Concrete

AAC is made from fine aggregates, cement, and an expansion agent, which causes the fresh mixture to rise like bread dough. In fact, this type of concrete is composed of 80% air. The material is molded and cut into precisely dimensioned units in the factory where it is manufactured.

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Thin bed mortar is used to join cured autoclaved aerated concrete blocks or panels. Walls, floors, and roofs can all be built with components. The lightweight material provides excellent sound and thermal insulation, and it is strong and fire resistant, as are all cement-based materials. AAC requires some type of applied finish to be durable, such as polymer-modified stucco, natural or manufactured stone, or siding. Find out more about autoclaved aerated concrete malaysia here.


  • For walls, floors, and roofs, autoclaved aerated concrete combines insulation and structural capability in a single material. Its lightweight and cellular properties make it easy to cut, shave, and shape; it readily accepts nails and screws; and it can be routed to create chases for electrical conduits and smaller-diameter plumbing runs. This gives it design and construction flexibility, as well as the ability to make simple changes in the field.
  • Dimensional stability and durability. AAC is a cement-based material that is resistant to water, rot, mold, mildew, and insects. The units are precisely shaped and have tight tolerances.
  • The fire resistance of the eight inch thick AAC is excellent, with a four-hour rating (actual performance exceeds that and meets test requirements for up to eight hours). It will not burn or emit toxic fumes because it is noncombustible.
  • Because of their light weight, AAC has R-values comparable to conventional frame walls, but they have more thermal mass, provide air tightness, and, as previously stated, are not combustible. When used as interior partition walls, the light weight also provides a high level of sound reduction for privacy, both from outside noises and from other rooms.
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However, the material has some limitations. It is not as common as most concrete products, but it can be shipped anywhere. Its light weight is advantageous if it must be shipped. Because it has a lower strength than most concrete products or systems, it is usually reinforced in load-bearing applications. Because the material is porous and will deteriorate if left exposed, it also requires a protective finish.


There are both blocks and panels available. Blocks are stacked similarly to traditional masonry, but with a thin-bed mortar, and panels span full-story heights. Within the wall section, grouted, reinforced cells and beams are placed for structural purposes. (A cylindrical core between two adjacent panels can be formed by concave depressions along vertical edges.) A vertical cell is typically placed at corners, on either side of openings, and at 6- to 8-foot spacings along a wall. Because AAC weighs about 37 pounds per cubic foot (pcf), blocks can be placed by hand, but panels, due to their size, usually necessitate the use of a small crane or other piece of equipment. 

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U-shaped bond beam or lintel blocks are available in 8, 10, and 12 inch thicknesses.

Some manufacturers sell tongue and groove blocks, which connect to adjacent units without the use of mortar at the vertical edges.

Cored blocks are available for the construction of vertical reinforced grout cells.

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