When thinking of concrete many think about cast in place concrete which is transported in an unhardened state (typically in a concrete truck), primarily as ready-mix, and placed in forms. This type of concrete is ideal for retaining walls and foundation walls. However, concrete has come a long way. Concrete is not just being used to build solid foundations and strong buildings but is now used in a more delicate way. This can be seen through precast and architectural concrete which show variations of visual design through form and finish.
Precast concrete wall systems can consist of a variety of shapes, and wall types. There are three basic categories: solid, sandwich and thin-shell in which precast concrete typically falls into. These can be panelized and erected in either a horizontal or vertical position and used on all types of structures including residential, commercial, institutional and industrial. Wall panels can “be designed as nonloadbearing or loadbearing, carrying floor and roof loads, as well as lateral loads”.
Solid Walls: refers to walls being made of solid concrete rather than including insulation.
Sandwich Walls: are wall panels that are cast with rigid insulation “sandwiched” between two layers of concrete. Sandwich walls can be strictly architectural, structural, or a combination of both. The insulation thickness can vary based on the desire for certain thermal capacity. This allows for a strong, insulated building with a façade that may have not been strong enough to hold the building alone.
Thin-shell: are wall panels that consist of a thin, outer layer of concrete typically ranging between 1.5 and 3 inches in thickness. This is connected to a system that is usually constructed of steel framing or studs, or sometimes concrete. This system is what connects the wall panel to the structural system of the building. It often allows interior finishes like drywall to be attached and typically holds a layer of rigid insulation between the exterior layer of concrete and the structural system. This type of precasting is generally seen in larger commercial or industrial buildings.
Architectural concrete is used for the exterior or interior finish of a building or structure. It often is cast with the integral reinforced concrete frame. Architectural concrete has become one of the most influential means of design in modern architecture. It is the only building material that can be used and processed in such a versatile manner. Many state that “through the design capabilities of the fresh concrete, virtually any shape and quality can be economically realized with the help of appropriate formwork systems and form lining”. Here are a few elements that alter the visual design of architectural concrete:
- form lining and formwork system
- concrete mix including type of cement and aggregates
- added pigments
- selection of a suitable release agent
- surface treatment (washing, sanding, polishing and sand-blasting)
- hydrophobizing impregnation, colour varnishing and coatings
Architectural concrete has been used more and more in residential homes as it provides the “industrial” look that many look for. In addition to creating a beautiful wall, architectural concrete is strong and is able to give support to your house or structure.
Concrete walls have come a long way and will continue to develop in the future. Concrete is not just a structural component but is also artistic and architectural.