REINFORCED CONCRETE

Reinforced concrete is a composite building material that consists of concrete (a mix of cement, aggregates, and water that when hardened resembles stone) and steel rods, bars, or mesh. The material possesses the best qualities of concrete, which is able to withstand compressive (latitudinal) forces, and iron, which is able to withstand tensile (longitudinal) forces. Reinforced concrete was patented in 1867 by French gardener Joseph Monier (1823–1906), who used iron to strengthen concrete for tubs for his nursery. During the second half of the nineteenth century the material was used in the construction of bridges and buildings. In the early twentieth century concrete reinforced with steel came into widespread use. In the United States, the first building made entirely of reinforced concrete was the William E. Ward House, built in 1876, in Port Chester, New York. In 1903 Cincinnati's sixteen-story Ingalls Building (called the Transit Building after 1959) became the world's first skyscraper with a reinforced concrete framework. The success of the building project revolutionized the construction industry. Skyscrapers—many of steel-cage construction, but others built with reinforced concrete—transformed the appearance of the American city and were the country's contribution to twentieth century architecture.

Reinforced concrete was predominately used in the construction of factories. In the early 1900s, German-American architect Albert Kahn (1869–1942) expanded the Packard Motor Company plant in Detroit, Michigan, designing what became a series of factories using reinforced concrete and steel. Kahn's innovative designs enclosed large spaces, often all on one floor and with ample windows for natural lighting, ideal for manufacturing operations.

reinforced concrete. Concrete once set will take a superimposed load that compresses it, but, if used, say, as a beam, will fail if heavily loaded, because it is weak in tension. Steel, on the other hand, is strong in tension, so the two materials are combined to enable the concrete to perform well in tension as well as in compression by casting steel rods in the positions where reinforcing is necessary to improve tensile strength, especially in beams, lintels, etc. Reinforced concrete can be used to construct entire skeletal frames, floor-slabs, walls, etc., either pre-cast in a factory or in situ (on site, i.e. where it will be permanently). Also called ferro-concrete it lends itself to the creation of complex curved forms that may get their stability partly from shape, permitting its use in bridges and shell-roofs. See also prestressed concrete.

Bibliography

A. Allen (1988, 1992);
Faber & and Alsop (1976);
Marsh (1907)

re·in·forced con·crete • n. concrete in which wire mesh or steel bars are embedded to increase its tensile strength.