What Does Post-tensioned Concrete Mean?
Post-tensioned concrete is a type of prestressed concrete where the concrete is strengthened via an arrangement of reinforcement held in tension. Steel cables, called post-tensioning tendons, are placed in plastic sleeves and positioned inside the concrete formwork before the concrete is poured. Once the concrete is poured and gained sufficient strength, the cables are pulled at either end (tensioned) and anchored on the outer edges of the concrete. The steel cables, like any steel object, may be subject to corrosion.
Corrosionpedia Explains Post-tensioned Concrete
Post-tensioned concrete is so called since the tendons are tensioned after the surrounding concrete has been cast (but before the concrete structure is subjected to service loads). Unlike conventional reinforced concrete, where the steel reinforcement bonds with the surrounding concrete, the post-tensioned tendons are not in direct contact with the concrete. Rather, the tendons are encapsulated in a protective sleeve that is cast into the concrete.
The large forces required to tension the tendons are transferred to the concrete, resulting in the application of a permanent compression in the concrete element upon anchorage. This constant compression increases the concrete’s flexural and shear strength, thus giving post-tensioned concrete several advantages over standard reinforced concrete, including:
- The ability to span longer distances
- Better resistance to shrinkage cracking
- The ability to be used on softer and more expansive soils
- Construction with fewer joints