Friday, January 31, 2014

For a better concrete, mix sand with bacteria and urea?

Concrete is the second most consumed substance on Earth, after water. It’s primary ingredient, cement, accounts for about 5 percent of the world’s carbon dioxide emissions. From bricks made with leftover brewery grains to concrete modeled after ancient Roman breakwaters, researchers have been looking hard for less energy-intensive alternatives.

And now urea. For his thesis project at University of Edinburgh, Peter Trimble wanted to see if it was possible to grow our building material instead of using intensive heat, Wired reports. “I thought, Is there an equivalent material that’s more environmentally friendly but structurally comparable out there?” he says. Turns out, all you need is some sand, bacteria, calcium chloride and a decent amount of urea.

Trimble’s design replaces the energy intensive methods with the low energy biological processes of “microbial manufacture.” He calls the method Dupe, and he's created a little stool capable of holding all his weight.

Pack sand (right on the beach) into a cast of a stool.
Then, pump a liquid mixture of Bacillus pasteurii, calcium chloride, and urea into that sand-filled mold.
The bacteria cements the sand particles together. When urea and calcium chloride come into contact with the bacteria, they form a bond (a biological cementation), creating a sandstone-like biomaterial.

More @