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Need a Building? Just Add Water

As an emergency shelter alternative to tents, which provide poor protection, and prefabricated buildings that are expensive to transport, two engineers working on their master’s degrees at the Royal College of Art in London have come up with a “building in a bag.” Erecting the “Concrete Canvas” structure entails adding water to a sack of cement-impregnated fabric and inflating it with air. The volume of the sack controls the water-to-cement ratio, eliminating the need for water measurement. The Nissen hut-shaped shelter is dry and ready to use in about 12 hours. The inventors said they thought of the approach after hearing about inflatable structures that are built around broken gas pipes to carry out repairs. “This gave us the idea of making a giant concrete eggshell for a shelter, using inflation to optimize the structure for a compressive load,” said co-inventor Peter Brewin. “Eggs are entirely compressive structures with enormous strength for a very thin wall.” A bag weighing about 500 pounds inflates into a structure with 172 square feet and would cost about $7,700. Full-scale production of the shelter is being planned. (www.wired.com)
Wired News (3/15/05); Rowan Hooper