What is post-tensioning?
Post-tensioning is the method of achieving pre-stressing after the concrete has hardened, thus taking advantage of concrete’s inherent compressive strength. Concrete is exceptionally strong in compression, but generally weak when subjected to tension forces or forces that pull it apart. This tension can result in cracking which can lead to large deflections that can cause distress in the building’s structure. The application of an external force into the concrete makes the foundation less likely to crack.
Why are post-tension foundations beneficial?
In many parts of the country, builders are faced with expansive soil conditions. Engineers must design foundation systems that are able to withstand larger soil induced shrink/swell movements, while at the same time maintaining an economic solution. These expansive soil conditions have increased the complexity of designs and have driven the need for economical post tension foundation solutions.
All concrete trends to crack as it cures. These are referred to as shrinkage (RTS) cracks. Although they are not usually detrimental to the performance of the foundation, they can be unsightly.
What is the value?
For homeowner and contractor, the value is knowing that their project is built on an engineered foundation that can resist the stresses of soil expansion while minimizing unsightly cracking. They will appreciate that post tensioning reinforcement costs about the same as traditional rebar reinforcing steel, but with a shorter installation time and reduced field labor costs, resulting in a more economical overall solution while providing superior performance.