Precast panels are sections of concrete that are formed and cured in a plant or factory, then shipped out into the field for installation. They are considered an alternative to traditional poured concrete, which must be formed, mixed, and cured out on construction sites. Precast panels allow concrete work to continue year-round, with much less impact from temperature and climate conditions.
This material is used in both building and earthwork applications. It can be used architecturally, as cladding or as a trim feature, or structurally, as walls, floors, and support members. Throughout much of Europe, precast panels are used in a technique known as double wall construction. Here, a precast panel is placed on either side of a steel support beam, allowing builders to quickly and efficiently erect a structure. These panels are also used as retaining walls or to support the stability of the soil when installing underground piping and equipment.
There are numerous benefits to using precast panels instead of poured concrete. Because the panels are produced in a controlled environment, they are of a much higher quality and smoother appearance than field-finished concrete. Once they have been formed in the factory, they can withstand extreme cold or heat, and will not suffer any damage due to precipitation. It is also much faster to erect precast panels than to build large concrete forms and wait for the concrete to set. Finally, the quicker installation times and elimination of form building often makes precast the more economical of the two.
Precast panels are constructed by individual precast plants. The material is poured into reusable molds or forms, then is cured, treated with a finish texture or sealer, and shipped to consumers. For some applications, the panels will be pre-formed to accommodate doors, windows, or other features, making installation of these items easier. The panels may also be pre-stressed, or subject to compression and other engineering techniques that make the product stronger. It may also be reinforced using wire mesh or rebar, which is necessary for certain structural applications.
There are no regulations or licensing programs in place that require certification of plants that manufacture precast panels. There are however, several voluntary certification bodies that will certify the products of a plant for quality, structural integrity, and strength. Most architects and engineers require that precast panels used on a job come from a certified plant, which reduces the risk of product failure. In the US, certification is done by the National Precast Concrete Association (NPCA)or the Architectural Precast Association(APA).