Precast concrete refers to concrete elements/units that are made in a factory and transported to site where they are joined to form a complete structure or part of a structure. Units range in size from bricks and blocks up to bridge beams. The sizes of large units are limited by the requirements for transport and lifting/handling on site.
Precast concrete is used for a wide range of important structural applications. Structural precast items would normally be either prestressed or reinforced. The factory type production for precast concrete lends itself to the use of prestressing. The use of prestressing produces more slender, and hence lighter, components than would be the case for reinforced components.
Precast structural concrete has a much better inherent fire resistance than structural steelwork and does not require secondary fire protection measures.