![]() This led to a surge in the popularity of CMUs in the United States. In 1900, Harmon Palmer patented the first commercially successful concrete block machine. Concrete masonry units were first invented in England in the 1850s and were later introduced to the United States in the late 1800s. The webs or fins are created by pouring concrete into the mold and then removing the excess concrete before the concrete cures. The concrete is typically made with Portland cement, water, sand, and gravel. CMUs are made by pouring concrete into a mold and then curing the concrete. ![]() CMUs are available in a variety of sizes and shapes with the most common size being 8 inches by 8 inches by 16 inches. CMUs are used in a variety of construction projects, including walls, foundations, and columns. They are typically hollow, with webs or fins that provide strength and help to reduce weight. The result will be a structure having the strength and durability of masonry with a popular, attractive stucco finish.Concrete masonry units (CMUs), also known as concrete blocks, are rectangular blocks made of concrete. With the right planning and preparation in the construction of the concrete masonry base, the final step is to follow the requirements of ASTM C 926, the Standard Specification for Application of Portland Cement Plaster, and the guidelines given in PCA's Portland Cement Plaster (Stucco) Manual EB049 in applying the plaster. A dash bond coat is a slurry mixture rich in cement, usually one part cement to no more than two parts sand, that is literally dashed against the wall using a brush, trowel, paddle, or machine. If open textured masonry units are not available or the condition of the masonry surface is questionable, apply a dash bond coat of a non-re-emulsifiable bonding agent to masonry surfaces prior to application of the basecoat. However, avoid saturating the masonry either by excessive spraying or by exposure of uncovered masonry walls or units to rain. Prior to application of the basecoat, uniformly pre-moisten concrete masonry surfaces to aid in curing of the plaster. Plaster is applied to concrete masonry surfaces in two or three coats, consisting of basecoat(s) and a finish coat. Because plaster and concrete masonry undergo similar volume changes, place control joints in the plaster only in locations that coincide with control joints in the concrete masonry. Cut all mortar joints flush, rather than tooling or sponge floating them. ![]() To enhance that inherent compatibility, select open-textured concrete masonry units that promote mechanical keying between the plaster and the base masonry wall. Traditional portland cement stucco should not be confused with the Exterior Insulation Finish Systems (EIFS) which are sometimes called "synthetic stuccos."Ĭoncrete masonry provides an excellent base for direct application of portland cement plaster. The term "stucco" is widely used to describe material applied to exterior surfaces. Portland cement plaster and portland cement stucco are the same material. The serviceability of traditional portland cement plaster has been proof-tested through long use in extreme environments such as the cold temperatures of Alaska and Canada, the hot temperatures of the humid Gulf States, and the dry Southwestern States. Portland cement plaster is a versatile, durable facing material that can be applied to either exterior or interior surfaces of a structure. ![]()
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