Masonry Magazine June 2008 Page. 34
AUTOCLAVED AERATED CONCRETE
Using
Autoclaved
Aerated
Concrete
Correctly
By Richard E. Klingner
Units of Autoclaved Aerated Concrete (AAC) are most commonly laid using thin-bed mortar and can be used for bearing-wall masonry. Design provisions for AAC masonry are given in the MSJC Code, and construction requirements are given in the Masonry Standards Joint Committee (MSJC) Specification. In this article, the manufacture of AAC is briefly reviewed; practical examples of AAC masonry construction are illustrated; MSJC design provisions for AAC masonry are summarized; and practical construction guidance for AAC masonry is emphasized.
AUTOCLAVED AERATED CONCRETE (AAC) IS A LIGHTWEIGHT, CONCRETE-LIKE MATERIAL WITH MANY SMALL, CLOSED INTERNAL VOIDS. Material specifications for AAC are prescribed in ASTM C1386. AAC typically weighs one-sixth to one-third as much as conventional concrete, and is about one-sixth to one-third as strong. It is suitable for bearing walls and shear walls of low-to medium-rise structures. Its thermal conductivity is one-sixth or less that of conventional concrete, making it energy efficient. Its fire rating is slightly longer than that of conventional concrete of the same thickness, making it useful in applications where fire resistance is important. Because of its internal voids, AAC has low sound transmission, making it useful acoustically.
32 Masonry
June 2008 www.masoncontractors.org
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