Manufacturing of Precast Concrete A mold is used to make precast concrete off-site. That is the primary distinction between precast concrete and site-cast concrete, which is poured directly into its final destination. Precast concrete is poured into a wooden or steel mold, which is reinforced with wire mesh or rebar. The cured product can then be removed from the mold and finished as desired. Precast panels are square or rectangular blocks of concrete that are manufactured in a factory and then shipped to the building site for installation. These panels are used instead of conventional cast-in-place concrete because they are more durable, easier to maintain, and less expensive to ship over large distances. Precast panels also require much less time and labor at the job site. The mold itself determines how the finished product will look. For example, if you were to use a mold made of glass, the resulting panel would be clear and could function as window glass or patio tile. If you used a mold made of metal, the panel would have a metallic finish that could be any number of things including decorative, functional (for example, to reduce noise pollution), or both. The most common type of mold is one made of fiberglass, but molds made of steel or plastic can also be used. Molds are needed on two opposite sides of the panel so that when the concrete has set, it cannot push out through the openings where the molds were located.