What is Prestressed Concrete?

Prestressing is a technique of introducing stresses of a predetermined magnitude into a structural precast concrete product to improve its behavior. This technique is usually found in precast concrete beams, spandrels, columns, single and double tees, wall panels, segmental bridge units, I-beam girders, and others. Prestressed, precast concrete products are typically crack-free under working loads and, as a result, look better and are more watertight, providing better corrosion protection for the reinforcing steel in the precast concrete piece. Concrete is cast around steel tendons—cables or bars—while they are under tension. The concrete bonds to the tendons as it cures, and when the tension is released it is transferred to the concrete as compression by static friction. Many projects find that prestressed, precast concrete provides the lowest overall cost, considering production and lifetime maintenance.