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Dirt makes a comeback

Modern man has developed a fixation for poured concrete, a material that requires a huge amount of energy and water to produce and must be brought in from elsewhere. And, at the end of its life cyle, concrete cannot be turned into anything remotely as useful as its original purpose. But, what are the alternatives? What other building materials are local, don’t require much energy and can return safely to the earth at the end of their useful life?

The answer is right beneath your feet.

When we think about building a home or making an improvement, we generally see dirt as the waste to be hauled away after excavating, usually at great expense. But with a relatively ancient technology known today as Rammed Earth, that soil can stay on-site and become your new walls, floors and even your foundation.

The process involves mixing a combination of earth ingredients, such as clay, gravel, sand, straw, lime and cement with water, which is compacted by special machinery in a removable formwork, similar to concrete. This method produces a hardened stone-like wall that can be structural, such as a foundation, or used as exterior walls. Another practical use is for flooring, which is a beautiful alternative to smooth concrete or wood. In addition to being Earth-friendly, Rammed Earth structures are great thermal masses—they absorb heat during the day and release it at night when it is colder, which is an important aspect of passive solar design. Although some climates are preferable to others, Rammed Earth can be used anywhere, and it is especially beneficial in remote locations.

Stephen Dobson of Ramtec Pty. Ltd. (www.ramtec.com.au), an Australian contractor specializing in Rammed Earth construction, has seen Rammed Earth become an increasing trend. “It WILL rise to the forefront and become a dominant form of construction all over the world,” he says. “Sustainability will push it to the front.”

Though the Rammed Earth method is practical, it is also very labor intensive. In areas where labor costs are high, such as the USA, this method could be more costly to consumers. Dobson has a different perspective, however. “Sure, there is a lot of labor involved, but the materials cost way less, so the overall finished cost is OK.”

Another factor that can offset the cost is a do-it-yourself approach to Rammed Earth. In lieu of special machinery, it can be done by hand. “Improvisation is always possible,” says Dobson, “Tibetans pound [the earth] with wooden poles. Chinese use bamboo forms.” Non-toxic sealers such as linseed oil can be used to treat and seal the material once it has been pounded and formed.

As the importance of sustainability grows in the construction industry, this method will be a central practice for most contractors. But, despite its ancient roots, the technology still needs to be brought into today’s mainstream, Dobson says. Contractors need to invest in the technology. Architects and designers need to familiarize themselves with the construction method, as well, to educate and persuade their clients. But the true power lies with the consumer, he adds, for only they can be the ones that both demand and implement the best practices.


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