Definition - What does Prestressed Concrete mean?
Prestressed concrete is concrete that is placed under a compressive load to give it specific advantages over other forms of concrete. The main purpose is to eliminate the tensile stresses than can occur on a concrete beam, thus making it less likely to fail in service.
Corrosionpedia explains Prestressed Concrete
While concrete handles compressive stresses very well, tensile stress can very easily cause concrete to fail. Prestressed concrete uses compressive forces to eliminate the tensile stresses being applied on a concrete structure such as a beam. These compressive forces allow prestressed concrete structures to be lighter and to be used for longer time spans than conventional concrete structures.
In order for concrete to be prestressed, some object or force applies a compressive load to the concrete, typically by a structural metal. This metal can be stretched before the concrete pouring process or it can be compressed afterwards. The prestressed concrete that has its structural metal form stretched before pouring is allowed to dry until the concrete reaches a satisfactory strength. Once it has reached this level of strength, the forces that are used to stretch the metal structure are released and the structure shrinks back to its original size. This return to its original form creates the compressive stresses necessary to create prestressed concrete.
The compressive stresses can also be added without stretching the metal form prior to concrete pouring. To perform this technique, the concrete is poured into the form, allowed to harden, and then steel tendons are stretched across the form and anchored, creating the compressive stress required to create prestressed concrete.