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Concrete Foundation Walls

There are numerous varieties of insulated concrete foundation walls, including Insulated Concrete Forms, and Precast Foundation Walls. Each offers unique advantages. When using concrete, it is often beneficial to use Concrete Admixtures, which can impact the concrete's workability, curing temperature range, set time, or color.

Insulated Concrete Forms

Insulated concrete forms (ICFs) are rigid plastic foam forms that hold concrete in place during curing and remain in place to serve as thermal insulation for concrete walls. The foam blocks or planks are lightweight and result in durable, energy-efficient construction. Because of their benefits¾including sound attenuation, impact resistance, and high R-value¾ICFs are desirable in above-grade applications as well as foundations.

[IMAGE: Insulated Concrete Form Picture]

ICFs allow trade contractors to construct concrete walls without a significant investment in reusable wood and metal forms. Because ICFs fit together easily and remain in place after concrete is poured, they can simplify and speed construction. ICFs increase the temperature range for pouring concrete to below freezing (freezing inhibits proper curing) by insulating the concrete until it is fully cured. ICFs can also result in stronger walls than standard cast-in-place concrete due to more constant, predictable cure during all seasons.

The three basic types of ICFs are hollow foam blocks, foam planks held together with plastic ties, and 4 x 8 panels with integral foam or plastic ties.

Precast Concrete Foundation Panels

Precast concrete foundation panels are cast and cured in a controlled factory environment. Built in the factory and installed on site in a fraction of the time of poured foundations, precast concrete panels help avoid weather delays. A typical panelized foundation can be erected in four to five hours, usually by bolting the panels together on site, without need of a concrete pour. The precast panels often come with rigid insulation already installed and furring strips pre-attached to the stud face to further simplify site construction.

Manufacturers are able to produce mixes that harden to 5,000 psi, which is stronger than concrete block or concrete walls formed and cast in the field. Panels range in size from 2-12 feet in width and 8-12 feet in height. They are typically installed by a crane, which lifts the panels into place on top of 4-6 inches of compacted stone.

Concrete Admixtures

[IMAGE: Precast Concrete Foundation Panel Installation]

Admixtures are materials that can be added to concrete either before or during its mixing to alter its properties, such as workability, curing temperature range, set time, or color.

Admixtures do not include cement, aggregate, or water. Some admixtures have been in use for a very long time, such as calcium chloride, which assists with cold-weather setting. Other admixtures are more recent and represent an area of expanding possibilities for increased performance. Not all admixtures are economical to employ on every project. Also, some characteristics of concrete, such as low moisture absorption, can be achieved simply by consistently adhering to high-quality concreting practices.

Based on their functions, admixtures can be classified into the following five major categories:

Other important admixtures that do not fit into these categories assist with bonding, shrinkage reduction, damp proofing, and coloring.

Cement substitutes, like fly ash and slag, can improve the quality of the concrete make it more environmentally friendly by substituting waste products for cement. Fly ash, slag cement, and silica fume are waste byproducts from power plants, steel mills, and other manufacturing facilities. Concrete substitutes also make good environmental sense because producing Portland cement generates significant greenhouse gasses.

Content updated on 8/4/2006

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