Components of a Precast Concrete Fence
Written by GJ Stott
A Precast Concrete Fence can be better understood by first defining its components.
What does precast mean?
The word “precast” simply means that concrete is “hardened before positioning; poured into a cast of the required shape and allowed to harden before being taken out and put into position” according to MSN’s Encarta Dictionary. Simply put, a precast concrete fence is formed before it is installed.
What is Concrete?
Again, the dictionary defines concrete as “artificial engineering material made from a mixture of cement, water, fine and coarse aggregates, and a small amount of air. The two major components of concrete are a cement paste and inert materials. The cement paste consists of portland cement, water, and some air either in the form of naturally entrapped air voids or minute, intentionally entrained air bubbles. The inert materials are usually composed of fine a material such as sand, and coarse aggregate.” Cement and concrete are often confused with one another. As you can see, cement is used in the making of concrete.
Precast Concrete Combination
The two components (precast and concrete) combined in a fence forming system create a product known as a precast concrete fence or wall. The fencing is precast, meaning that it can be manufactured somewhere besides it’s final position, typically an offsite forming facility, sometimes onsite and then transferred into its final position, unlike a common block wall or brick wall which is constructed in place.
Development of the Precast Concrete Technique
There are many kinds of precast concrete fence products available in the marketplace. Initially, one of the most commonly used items was precast concrete stone columns. These are usually found in older areas of the United States and abroad had wire strung between a series of posts to create the concrete fencing. As interest in using concrete as fencing materials increased, the first uses were plain concrete segmental panels that were installed by being stacked between concrete posts at various lengths. These panels were produced in a pan mold and were not textured. The precast concrete fence posts were poured with a slot on either side similar to an I-beam. The industry progressed to a point where the bottom of the pan mold was textured, and the open side of the panel was trowel or broom finished, resulting in a textured or molded finish on one side only.
In the early 1980’s developments were made to the precast concrete forms which produced the segmental stackable fence panels poured vertically thereby creating an equal textured finish on both sides. The post forms also duplicated the same texture as the panels and a more aesthetically pleasing product entered the market.
Precast concrete fence products today are available in a variety of different textures and sizes, from smaller modular systems using one foot by five foot panels that stack one on top of another between five inch concrete posts to larger systems with panels greater than twenty feet long and fence panels greater than twenty feet high. Most of the larger systems continue to be poured in a horizontal position, but there are now full panel systems greatly improved from the old modular systems with large one piece sections that are being cast vertically, providing a molded textured finish on both sides of the concrete fencing.
AFTEC’s Precast Concrete System
The industry has grown rapidly with new developments continuously occurring. One such example is known as Combo-Cast™, a system whereby the precast concrete fence column and wall panel are cast as one integral unit instead of separately. This type of precast concrete wall manufacturing provides many efficiencies cutting down labor in production, handling and installation. The forming systems are also designed to enable the textured wall form liners to be interchanged so that a variety of finishes can be produced from a single form.
As the development of precast concrete fence technology expands so are the components that are used to produce the precast concrete products with new and innovative additives to concrete and reinforcement materials becoming rapidly available to this ever changing industry.