RECOMMENDATIONS

Carefully estimate quantities of concrete required on the jobsite; that help to reduce waste and save raw materials and energy.

Utilize concrete's qualities such as fire resistance, thermal mass, and longevity.

Consider precast systems to reduce job site operation and minimize the amount of waste. Modularity simplifies precast production.

Specify fly ash because it is a recycled product that substitutes a portion of a cement, using fly ash environmental impacts are minimize.

Specify recycled aggregate: reduce the amount of material going to the landfill and the mining operations.

FOUNDATIONS:

Ways to reduce the amount of concrete:

- Monolithic foundations minimize the need for concrete because foundation footings need only be 12" deep in most cases. Slabs eliminate the need for floor framing material, as well.

- Frost-protected shallow foundations reduce the amount of concrete used by avoiding deep footings.It uses foundation perimeter insulation that captures heat from the building to prevent frost heaving beneath the structure.

- Canadian Thin Wall technology, which utilized poured concrete walls that are 6" thick instead of the standard 8"

- Fly ash can be used as a pozzolan replacement for 15% to 35% of the cement in the concrete mix by weight, depending on the type of fly ash and the application. Fly ash can also provide part of the fine aggregate needed in the concrete, or act as the binder in concrete masonry units. Fly ash adds strength and durability to the final concrete product.

Simple slab foundations are the most cost-effective option. Using precast concrete panel foundations, saves nearly 75% of the concrete in a typical poured foundation. The only problem with the precast is the transportation. (5)

Typical foundation concrete contains about 15% Portland cement. The Portland cement is produced by cooking limestone, silica and clay in an energy intensive process that is frequently powered by burning hazardous wastes or tires.

- To improve the thermal efficiency of the concrete use autoclaves concrete (ACC); this improves the thermal resistance of an 8" wall up to five times that of concrete alone.

-Use formwork that can be reused or use integrated forming systems that can stay in place as insulation for the finished wall.

 COMMENTS

Require from the contractors to incorporate waste minimization and pollution prevention actions. Minimize off-cutting by careful and precise dimensioning of materials.

Concrete is a rock-like mass with remarkable strength and durability that has been used as an architectural material for almost 2000 years since the Roman times.

Lightweight interlocking foam blocks or panels can be used as permanent concrete form. This require less concrete than ordinary poured foundation. The post and beam systems in particular consume far less concrete. (3) It is important that foam forms are properly braced during pours to avoid concrete leakage.

- Foam forms are derived from petroleum, and foam insulations require a great deal of energy of manufacture. At the present these systems are not able to use recycled foam in their manufacture.

- The bond formed by the foam and concrete fill could make the materials difficult to separate for recycling when the building is demolished or remodeled, although unused scrap from the construction site can often be recycled.

Concrete structural systems still represent a small percentage of the residential market in the US, but offer a viable alternatives to wood framing.

 SOME DATA

Worldwide cement production totaled 1.25 billion tons in 1991, according to the U.S. Bureau of Mines. (5)

The average American home uses nearly 14 tons of concrete in its construction (majority for foundations and slab) (3)

According to the AIA , fuels burned during the manufacture of cement produce approximately 8% of all carbon dioxide emissions worldwide.