Post-tensioning is a way to reinforce concrete. This can be completed as the structure is being construction or after it is functional. Pre-stressed concrete means the material has been subject to compression before being placed. It strengthens the concrete to improve the performance of existing structures.
Metal tendons, typically made of steel, are used to support concrete and can be used in between layers of concrete, or as bracing once the structure is functional. These tendons can consist of single wires, multiple stands of wire, or threaded bars. Reinforcing the concrete as it is being poured is standard in many applications.
Bridges are an ideal example of how tendons are used during construction. Anyone who has been stuck in traffic on the highway due to bridge work sees this in action. The bottom layer of concrete is poured, wires or bars are placed on top of that, and another layer of concrete is poured. This continues until the project is completed.
The purpose is to allow the bridge to withstand tons of weight at once. A flat bed trailer that is transporting heavy equipment, rush hour traffic, and the weight of ice and snow all has to be supported by the bridge. Concrete alone would not be strong enough to support all that weight. The risk of a collapse is all but eliminated with the use of threaded bars.
Foundations and floors are reinforced to stand up to the pressure of multiple floors. Hospitals, office buildings, parking garages, and apartment complexes are a few examples of buildings that require reinforced concrete. Tall structures are especially vulnerable to weight and pressure because gravity is also a factor. Flooding, earthquakes, lighting, and accidents can compromise the building and render it unsafe.
Concrete is a porous material that is susceptible to damage over time. Corrosive agents, salty sea spray and chlorides, sand and salt on highways, thermal changes, and the effects of pollution will result in damage to the concrete. Post-tensioned concrete restoration services are then required to enhance structural integrity and ensure safety. Experienced engineers and technical professionals use advanced technology to develop custom solutions for restoration projects.