If you've ever been part of a construction project
However, that is slowly beginning to change. Cement is still the preferred material in construction, but the focus is slowly veering away from on-site cement pouring to pre-cast concrete. This is because pre-cast concrete is made in plants under controlled conditions and has to meet high quality standards compared with cement that is merely poured on-site. Now, what makes pre-cast concrete so special?
In a nutshell, pre-cast concrete is wet cement poured into existing molds at the factory. The concrete blocks are then shipped to the construction site and installed. This way, the contractor or project manager can be sure that the blocks are all strong and identical, which are characteristics that are hard to achieve during on-site cement pouring.
During on-site cement pouring, a temporary mold is made, used, and then disposed of. However, in pre-cast concrete plants, there are molds that are used again and again. This ensures that all of the blocks that came out of the same mold are identical both in size and shape. Pre-cast concrete plants use wood and steel molds; steel is commonly used for larger projects because of its strength and reusability.
Depending on the type of building that the pre-cast concrete blocks are going to be used for, the plants use different techniques. To cast concrete molds for low-rise buildings, plants typically place a steel mesh in the middle of the block to reinforce it. For bigger, high-rise buildings, iron bars are placed in the middle of the block to make it even stronger.
Concrete always has two archenemies: water and air. Water and air pockets that form inside the concrete when casting concrete molds can expand when temperatures change. This will cause damage to the blocks, which is dangerous if the blocks are part of a building's foundation. Pre-cast blocks avoid this by taking measures to make sure that no water or air pockets form during casting.
Pre-cast concrete isn't limited to building foundations, however. If you talk to companies that offer concrete solutions, they would tell you of pre-cast concrete's other uses in projects like storm cellars, sewers, landscaping, decorative items, and more. The thickness of pre-cast concrete can also be adjusted depending on its use. For more information, you can visit wisegeek.com/what-is-precast-concrete.htm.