What is autoclaving? Why are some concrete masonry units autoclaved units whereas others are not?
Autoclaving is a method of curing concrete masonry units under high pressure and steam. The process of autoclaving reduces the linear shrinkage of the concrete masonry units to approximately one-half that which occurs under low-pressure steam curing. Most Type 1 concrete masonry units are autoclaved units, which generally are expensive and are not available in all areas. In most cases, designers should specify Type 2 units. Twice as many control joints should be used for a CMU wall constructed of Type 2 units as opposed to Type 1 units.