Precast concrete is a form of construction, where concrete is cast in a reusable mould or "form" which is then cured in a controlled environment, transported to the construction site and lifted into place. In contrast, standard concrete is poured into site specific forms and cured on site. Precast stone is distinguished from precast concrete by using a fine aggregate in the mixture so the final product approaches the appearance of naturally occurring rock or stone.
By producing precast concrete in a controlled environment (typically referred to as a precast plant), the precast concrete is afforded the opportunity to properly cure and be closely monitored by plant employees. Many states across the United States require a precast plant to be certified (either by APA, NPCA or PCI) for a precast producer to supply their product to a construction site sponsored by State and Federal DOTs. There are many different types of precast concrete forming systems for architectural applications, differing in size, function and cost.
Precast architectural panels are also used to clad all or part of a building facade free-standing walls used for landscaping, soundproofing and security walls. Storm water drainage, water and sewage pipes and tunnels make use of precast concrete units. The advantages of using precast concrete is the increased quality of the material, when formed in controlled conditions, and the reduced cost of constructing large forms used with concrete poured on site.
Volumetric mixers are no strangers to the precast industry as manufacturers have built mixers to serve many different markets under the all encompassing title of Pre-cast. Any industry that requires a mold for concrete will most likely have some form of a volumetric mixer found in their plant. Volumetric mixers have produced concrete in simple applications such as the ornamental industry all the way to large pre casting facilities that produced large elliptical pipe using dry cast. Other applications have included burial vaults, pre-stressed concrete beams, to on site slip form pre-casting of smoke stacks for power plants.
A big issue for this market is the ability to have pin point accuracy so that molds and forms can be poured and achieve the strength required to strip them in a specific time frame so that pre-casters can increase their production. Volumetric mixers have been hitting the mark for years on this front as numerous pre-casters have successfully used these types of mixers to increase their production, and reduce their cost.
While many pre-casters control their production through producing their own concrete many do not, and it can become a problem to have molds ready to be filled and the supplier unable to deliver at the designated time.
Strip times are delayed which in essence is a delay in production and puts the pre-caster behind schedule. The ability to produce your own concrete on demand at an affordable price is a major plus. A volumetric mixer can be an answer for many who are in the pre-cast industry.