What is a concrete masonry unit?
A concrete masonry unit (CMU) is a rectangular block made of concrete which is also referred to as a cement block or concrete block. When construction is referred to as “CBS construction” or a “concrete block structure,” it means that concrete masonry units were used to build exterior walls and interior support walls. CBS construction is found in n both residential and commercial building construction.
Concrete masonry units provide considerable strength, also making the units ideal for structural foundations to support wood frame buildings. Concrete footings are installed in excavations marking the building’s footprint or perimeter and a mason then builds the foundation and wall on that footprint.
A mason lines the concrete masonry units in layers or courses of overlapping concrete blocks. Each layer of block is known as a “wythe,” and the mason stacks the masonry units vertically, joining them with concrete mortar. The concrete masonry units are designed with core holes in which steel reinforcing bars known as “rebar,” are inserted vertically for stability. A concrete mixture is then poured into the core holes to provide greater stability and strength.
One important consideration for CBS construction is the inclusion of “weep holes.” The holes are placed in various sections of the concrete masonry construction, allowing any water that may accumulate inside the block walls to “weep” from the building. The weep holes also serve to equalize air pressure on both sides of the wall.
A typical concrete masonry unit is 8x8x16 inches in size. Although concrete masonry units are called cinder blocks, a cinder block actually contains an aggregate of cinders or fly ash, making cinder blocks slightly less strong than the concrete blocks.
Concrete <a href="http://products.construction.com/SearchResults/Top/unit%20masonry">unit masonry</a> is used for walls for buildings. However, other uses for concrete masonry units include retaining walls, chimneys, fireplaces, and firesafe enclosures of stairwells, elevator shafts, and storage vaults. If you are interested in even more information, check out the McGraw-Hill Sweets Network, my employer. They have a list of products, manufacturers and detailed information, even CAD info. It’s amazing.
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
