What does post-tensioning refer to in concrete construction?

Post-tensioning refers to a method in concrete construction where high-strength steel tendons are embedded within the concrete but are not initially under tension when the concrete is poured. After the concrete has cured and reached a certain strength, these tendons are then stressed, or tensioned, using hydraulic jacks. This process creates compressive forces in the concrete which helps counteract tensile stresses that may occur when the structure is subjected to loads.

This technique is crucial in increasing the load-bearing capacity and durability of concrete elements, allowing for longer spans in bridges, slabs, and other structures, while also minimizing cracking and reducing shrinkage effects. It is particularly beneficial in designs where reduced structural depth is desired.