Prestressed concrete

Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It is a material that has the characteristics of high strength concrete in compression and high ductile strength steel for tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete. It is often used in commercial and residential construction as a foundation slab. Prestressing tendons (generally of high tensile strength steel cable or rods) are used to provide a clamping load which produces a compressive stress that balances the tensile stress that the concrete compression member would otherwise experience due to a bending load. Traditional reinforced concrete is based on the use of steel reinforcement bars, rebars, inside poured concrete. Prestressing can be accomplished in three ways: pre-tensioned concrete, and bonded or unbonded post-tensioned concrete.