Precast concrete

precast concrete

Concrete cast into structural members under factory conditions and then brought to the building site. A 20th-century development, precasting increases the strength and finish durability of the member and decreases time and construction costs. Concrete cures slowly; the design strength is usually reached 28 days after initial setting. Using precast concrete eliminates the lag between the time on-site concrete is placed and the time it can carry loads. Precast concrete components include slabs, beams, columns, walls, stairways, modular boxes, and even kitchens and bathrooms with precast fixtures. See also prefabrication.

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Precast concrete

Concrete that has been cast into a form which is later incorporated into a structure. A concrete structure may be constructed by casting the concrete in place on the site, by building it of components cast elsewhere, or by a combination of the two. Concrete cast in other than its final position is called precast.

In contrast with cast-in-place concrete construction, in which columns, beams, girders, and slabs are cast integrally or bonded together by successive pours, precast concrete requires field connections to tie the structure together. These connections can be a major design problem.

Precast units can be standardized. Savings can then result from repeated reuse of forms and assembly-line production. Furthermore, high quality can be maintained because of the controls that can be kept on production under plant conditions. However, there is always the possibility that transportation, handling, and erection costs for the precast units will offset the savings. See Concrete, Prestressed concrete