Source: Masonry Construction
Publication date: January 1, 1999
By Michael Chusid
Abstract: The key to AAC's physical properties is its high air content--80% of its volume. Autoclaved aerated concrete is made by mixing portland cement, silica-bearing sand and water slurry with a finely powdered aluminum.Autoclaved aerated concrete block make a mason's job easier. They're lighter than conventional concrete block, soft enough to cut easily and those with recessed hand grips carved into the ends make grasping much easier. They're also larger, making them quicker to install than conventional concrete block and improving a mason's relative productivity. The per unit and overall weight reduction should reduce the risk of back injuries as well. Their solidity changes the way AAC block are laid. Since the block are precision cut, it is easy to keep a wall plumb and square as it goes up. Since AAC units are fully bedded, AAC joints distribute loads over a full block face to create a very strong joint. AAC can be cut and shaped with simple hand and power tools. This reduces the noise, dust and dust-related health risks of using high-speed diamond saws to cut conventional masonry units. One area is lacking, though. AAC is friable, water absorbent (similar to CMU) and not especially aesthetically pleasing , and therefore must be given a plaster-type finish or other protective veneer. However, the ease with which AAC can be cut and shaped helps to compensate for this shortcoming. T...
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