Environmentally Secure Concrete Houses

Addressing the Need for Permanent Shelter in Hawaii

Options For Residential Construction in Hawaii

© 1993 John August

Thatched palm and bamboo structures have been in use in the Pacific region and elsewhere for thousands of years. As a renewable resource these structures flourished due to availability of materials and ease of construction. On the downside, wind, rain, rot, fire, and bugs quickly degenerate these structures. And the realities of a 20th century lifestyle in Hawaii - with incumbent electronic accoutrements and creature comforts - create a questionable need to continue building in this vein.

Lumber, once a plentiful and inexpensive resource, is rising in cost and decreasing in availability. Deforestation is not only a source of environmental imbalance, but is extremely short sighted in its economy. Besides that, wood is subject to the same decay scenario as palm and bamboo.

Steel can be a cost effective alternative to wood, but the industry which produces it is highly polluting. And although strong and durable, it can be extremely vulnerable to salt and water. Framing systems using steel still resort to wood sheathing and the use of gypsum, both materials with limited lifespans.

Plastics can be excellent insulators but as of yet have extremely limited structural applications. Their major drawback is toxicity with heat, not to mention high fire risk.

The last option is concrete. Although strong and durable, it is heavy, dense, hard to work with, and usually more costly. A common major complaint about concrete is it being cold and damp. However, a new hybrid called Lightweight Composite concrete shows excellent promise as a building medium.

Most concrete produced is in the density range of 150 pounds per cubic foot (pcf). Lightweight structural concrete begins at weights below 120 pcf. All concrete must achieve specific strengths depending on its application. For example, a roof may require less strength than a footing. The reduced density provides more insulation, while a denser footing can bear a greater deadload.

For tropical seaside residences this means a more even temperature gradient inside the dwelling throughout the day instead of roofs (especially metal and composition roofs) acting as radiant heaters as the sun beats down on them. And inversely, those Hawaiian homes at higher elevations with cooler climates will use less fuel for heat.

Lightweight composite concrete is made with a variety of lightweight and normal aggregates, synthetic fiber reinforcement, and preformed foam. This foam has the appearance and texture of aerosol shaving cream and is injected into the concrete mix, much like adding egg whites to a cake. With one exception. The bubbles don't break down when you mix them in. For further information see the section on Lightweight Composite concrete.



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