Precast wall panels are used in a wide variety of construction projects, especially where sturdy reinforcement walls are needed. They are almost always made of concrete, but the precise design varies and the size and shape can depend on the type of panel. They are generally six to eight inches in thickness, and there are two different kinds of panels.
Concrete precast panels are made indoors in highly controlled environments, which allow manufacturers to be much more specific in terms of materials and processes. For instance, on-the-spot concrete walls must dry in the environment they are created in, subject to outside elements and moisture levels. On the factory floor, concrete dries with exact humidity controls and precise temperatures, making it stronger and more evenly cast than other versions. Once the concrete is set, it can be braced and sealed according to exact specifications before being shipped out.
The first precast wall panels were made of what is known as precast cellular concrete. The cellular tag does not refer to the chemical composition of the concrete---a common mistake---but rather to the way the concrete itself is cast. For these walls, some type of inner framework is needed to give the panel form and strength, keeping the walls intact during transport and placement. Steel beams are the most common type of framework used, but the materials can vary. When the concrete is poured, holes are deliberately formed through the panels for these steel bars to fit through, giving the concrete "cells" or spaces for the framework.
The concrete used can be either normal or custom designed, depending on the need. Often the concrete and the films used to cover it are made to be as fireproof as possible, since precast panels are often used strategically in large buildings as fire walls to protect more sensitive places from a growing fire.
Insulated and Carbon Walls
The second type of precast walls are newer versions that attempt to improve on the design by sandwiching other materials inside two concrete panels. Often, a foam insulation is used, which has similar fireproof and heat-containment abilities to concrete but is much lighter. One of the latest manufacturing processes also uses carbon fiber trusses and supports instead of steel. The carbon fiber is extremely resilient, yet is much lighter than the steel versions and offers more flexibility. These insulated and carbon-based versions cost significantly more than the solid concrete panels with traditional framework.