Post tensioning represents one of the best methods by which concrete can be reinforced during the construction phase. Unfortunately, many people fail to capitalize on this highly effective strategy--simply because they don't understand it well enough. If you would like to boost your knowledge of contemporary concrete installation techniques, read on. This article will introduce you to the world of post tensioned concrete.
The purpose of post tensioning is to improve the structural integrity of a concrete surface, thereby ensuring that it lives up to its full lifespan. At the heart of a post tensioning system are special braided metal cables known as tendons. These tendons run inside of hollow plastic tubes that are put in place before the concrete is poured into the forms. After the concrete has cured, the cables are pulled taut from either end and secured against the walls of the concrete. The tension of the cables thus adds a significant measure of strength to the concrete.
As a technique of reinforcing concrete, post tensioning belongs to the broader category of techniques often referred to as prestressing. This term simply denotes the fact that the metal cables are stressed (i.e. tightened) prior to any structural load being added to the concrete. Post tensioning differs from most forms of prestressing in that the metal cables are not tightened until after the concrete has been poured. This is possible thanks to the plastic sleeves in which the cables are housed. This greatly simplifies the tensioning process, since now the hardened slab is capable of acting as an anchor for the cables.
The benefits of post tensioning don't stop there, however. Compared to both other prestressing techniques and those that utilize rebar as a reinforcing agent, post tensioning does a remarkable job of preventing so-called shrinkage cracks. Such cracks are a natural part of the curing process in most concrete slabs. Yet thanks to the incredible compression generated by post tensioning, shrinkage cracks are kept at bay almost entirely.
Not only that, but post tensioning allows builders to achieve better results with thinner foundations, thus keeping materials costs at a minimum. This is a direct result of the extra strength provided by the post tensioning cables. Post tensioning also permits foundations to be built atop soils that would otherwise be considered to risky. Such soils include those with a high percentage of clay, as well as though that are especially water logged. The internal stability of post tensioned concrete allows it withstand a much greater amount of ground shifting.