What is a Concrete Masonry Unit?

The common cement block is known in the concrete industry as a concrete masonry unit. Usually the unit designation is abbreviated to CMU. The typical concrete masonry unit is a rectangular block manufactured of Portland cement and an aggregate, most often sand or filtered gravel. This process produces a high density concrete block. Concrete masonry units may be actual high-density concrete blocks, or they may be lower density cinder blocks, manufactured with an aggregate of fly or bottom ash. Additionally, there are clinker blocks, manufactured with aggregates of smelting wastes, usually coal, coke, slag, or grit. Aerated concrete may be used in the manufacture of very strong, yet relatively lightweight concrete masonry units. However, the prohibitive cost makes the use of aerated CMU's fairly rare. The most common concrete masonry unit is considered to be 8 inches by 8 inches by 16 inches (20 cm by 20 cm by 41 cm). Actually, all CMU’s are 3/8 of an inch (1cm) smaller all the way aroun ... more