The way to treat concrete is called Prestressed, it reinforces the strength and it’s resistance to tension and erosion. The concrete is naturally weak to tension if not prestressed, the more weight place on it, the more cracks begin to form and the weaker it will become. Using the series of steel cables and rods to compress the concrete that is pre-stressing. The concrete that is compressed will become stronger on its tension resistance. The concrete that treated pre-stressing can match to the pressure treated wood.
By exposing the concrete to a certain test, the structure of it makes stronger and more durable. It also reinforced with steel bars called rebar for more strength to its load-bearing capabilities. The concrete is generally able to withstand cracks if it pre-stress and is more cost effective for reinforcing large slabs of concrete. Within the concrete has a lesser number of joints so it cuts down on maintenance costs during the overall life of the building. The three ways to pre-stress the concrete is through pre-tension, bond post-tension, and un-bond post-tension.
After concrete first pours out it cast over tense bars. When the bars are already under maximum tension, it bonds to the bars and is compress when the tension release. If the concrete already as compressed as possible it does not need any compress more. So if any extra tension gives on the concrete it transferred back to the steel bars inside. Usually, the pre-tension concrete is prefabricated it takes amazingly strong anchors to stretch the metal bars inside the concrete. Basically, the pre-tension concrete only yields a small section of the concrete at a time.
Bonded Post-tensioned Concrete
Bonded post-tension is a type of concrete that compressed after it pouring out, not during the casting process. The concrete during casting is poured out around ducts made of steel or aluminum. Where the concrete is expected the ducts are placed in that area to experience tension. When it is finished that is a series of rods are passed through the ducts before the concrete. Once the concrete is hardened is then now allowed to set. Then using the hydraulic jack to create pressure on the concrete and stretch the bars inside. The ducts are sealed with grout after the bars are stretched and the jacks are removed. To avoid water from seeping in and causing rust or corrosion. In this case, it rigid and reinforced the concrete.
All of the entire slab of concrete, not only the tension rods, inside, absorbs fluctuations due to temperature. The pre-stressed concrete in this method can be made on a larger scale. Usually, used for the foundation slab for buildings and in parking garages. The bridges before were also made out of this type of concrete, recently, researchers have found that the ductwork can sometimes be sealed improperly. That leads to corrosion and in severe cases the bridges collapse.
Un-bonded Post-tensioned Concrete
Similarly, this type of concrete is the same as the bonded version, nonetheless, the rods inside are grease and provide flexibility. The cable that inside the concrete can be individually adjusted after the concrete has already set and the need for grouting inside the ductwork is eliminated.