Structural concrete, also known as reinforced concrete, is the part of the building that supports the weight of everyone and everything inside of it. This type of concrete is normally cast-in-place, meaning that they are poured, reinforced, and cured in its final position during the early phases of construction. Foundations, slabs, columns, and some types of walls can be cast on site, especially large segments that may be difficult to transport. Structural concrete contains metal reinforcements, like steel rebar or post-tension systems, that allow it to bear the entire weight of the building without failure. Most often, there are some elements of that are cast on-site and some that are precast – like stairs, footings, and support beams.