Date: Apr 13, 2012 Source: (
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For almost 40 years, engineer David Easton has been recognized widely as the American guru of rammed earth construction.
Now he's beginning to experiment with a new development in that ancient method: rammed earth building blocks.
Traditional rammed earth involves a process of compacting five-to-ten-inch layers of moist soil, gravel, clay, and silt, with cement as a binder, and using a pneumatic tamper to pound it down in between metal or plywood forms. Built on site, the result is a wall that combines structure with finish -- an earthquake-resistant form with colors that are regional, since they're derived from the earth nearby. It requires a crew of about ten specialists to build the forms and tamp down the earth.
But his blocks, currently manufactured with equipment that he's developed, require no framework and can be trucked to a building site. They're similar in size to concrete blocks, but they're compressed, rather than steam cured. And they're more efficient.
"More people can do the work because it's easier to lay block than build a form," he says. "There are only a handful of rammed earth experts out there, but there are thousands of masons."
He likens the development of these blocks to that of experiments by Frank Lloyd Wright, Mario Botta and Will Bruder. "It's a watershed moment in the practice of building materials," he says. "It's a return to earth as a globally significant building material -- it's the sustainable thing to do. There's less embodied energy, they use waste aggregate, and also use less cement than concrete blocks."
He's already built a small, 1,200 square-foot guest house in Napa, and plans to break ground on a larger, 3,200 square foot home there next month.
The idea, he says, is to develop respect for earthen materials.
"That's why I got into it decades ago," he says. "I wanted earth to be an exemplary material."
For more on David Easton, go to http://www.rammedearthworks.com/
