Earthbag Construction

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Earthbag walls can be linear, free-form or a perfect circle formed by the use of an architectural compass. Arched windows and doorways are built around temporary arch forms until the keystone bags are tamped into place. The finished walls then cure to durable, cementlike hardness.

Earthbag construction helps avoid wood consumption for the walls, and it also can eliminate wood for the roof frame where corbelled domes are utilized. Conventional wood roof systems consume a lot of trees. This may be sustainable for those who dwell in forested areas, but for people living in relatively treeless areas, designing corbelled earthbag domes offers an opportunity to create shelter using the Earth’s most abundant natural resource—earth itself. Why cut and haul lumber when the most common, versatile, energy-efficient, cost-effective and termite-, rot- and fire-proof construction material is available right at home

EARTHBAG STRENGTHS

Another advantage of earthbags is the tensile strength inherent in the woven-poly bags when combined with the use of four-point barbed wire. It’s sort of a double-whammy of tensile vigor not found in most other forms of earth construction. Rammed earth and even concrete need reinforcing rods to keep them from pulling apart when placed under opposing stresses. The combination of a textile casing and barbed wire builds this tensile strength into every row of an earthbag structure.

In order to use some forms of earth construction in humid environments, a percentage of cement, lime or asphalt emulsion must be added to chemically alter the composition of the earth, making it resistant to water absorption. Earthbags, on the other hand, can effectively utilize raw earth for the majority of the walls, even below ground, because the bags provide mechanical rather than chemical stabilization. The textile bag supports the raw earth even when fully saturated. This means builders can use a wider range of soil options, extending earth construction into nontraditional earth-building regions such as the Bahamas, the South Pacific and a good portion of North America.

Khalili has demonstrated the structural integrity of his raw earth (nonchemically stabilized) earthbag domes. Under static testing conditions simulating seismic, wind and snow loads, the tests surpassed 1991 Uniform Building Code requirements by 200 percent. These tests were done at the California Institute of Earth Art and Architecture (www.calearth.org) under the supervision of the International Conference of Building Officials. The earthbag system has been proven to withstand the ravages of fire, flooding, hurricanes, termites and two earthquakes with magnitudes of more than 6 and 7.

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