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Autoclaved Aerated Concrete (A.A.G.)

A lightweight form of concrete manufactured from sand, cement, recycled material, lime, gypsum and an aerating agent, aluminium paste. Used in pre-cast products such as building blocks and panels.

Auotclave

A chamber in which various cement based products are subject to an environment of high pressure steam to speed up the hardening and curing. Typically the design strength can be achieved in 24 hours or less.

Recognised as being highly thermally and acoustically efficient products made with AAC are gaining awards for being "Eco friendly". They are getting popular with major construction companies and owner builders alike because of their ease of use and labour saving potential.

Something like 80% of the total product comprises air voids and you can imagine that quite large pieces can be handled safely by one person.

The Portland cement, sand, lime, gypsum and lesser material is mixed as a slurry with powdered aluminum. This reacts with the cement and lime to produce hydrogen bubbles which increase the volume by about five times.

This is done in large long forms and when the material is set, it is removed from the forms, cut to the desired shapes and cured in an autoclave.

Hebel in Australia list the following uses of Autoclaved Aerated Concrete.

• Wall Systems. Panels that fix to framed walls as exterior strength, impact resistance and insulation. Large blocks, typically 250 wide for external walls and 100 wide for internal built like traditional brick walls or concrete blockwork these blocks are glued together with the manufacturer's adhesive.
• Floor Systems. Various panel sizes and thicknesses form the basis of solid floors when they are screwed or glued to timber or steel floor joists.
• Fence systems Lightweight panels that provide quick easy to build fences.

The DIY find these AAC products particularly inviting because they can be cut to shape with ordinary hand saws and other cutting tools.

One last point is that houses using these products rate well in bush fire prone areas and the fact or their good fire safety rating is a plus for all homeowners wherever the location

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