Concrete possibilities | Economist.com

Concrete possibilities | Economist.com:

"(M)aterials scientists have long known that they can tweak the basic concrete recipe to create any number of desired effects. For example, adding chemicals that encourage the trapping of tiny air bubbles makes concrete more durable, because it gives water room to expand into when it freezes, thereby avoiding tiny cracks. In the late 1990s researchers began to experiment with another additive—small amounts of electrically conductive steel or carbon fibres. Even though the fibres make up less than 1% of the concrete by volume, they have a large effect: the resulting concrete gains the ability to conduct electricity."

There are important applications for the conducting concrete.

In Housing

"Grancrete, a company based in Mechanicsville, Virginia, has been working on a new type of ceramic, cement-like material for making quick, durable and cheap “spray-on” housing for the billion or so people in the world who lack it. Grancrete, as its invention is known, has its origins in a material invented to encapsulate nuclear waste. Its developers soon realised, though, that its real potential lay in housing people, rather than plutonium.

" small local team can be trained to mix and to apply the grancrete, which is made from a mixture of sand and a special binding agent. The team uses a hose to spray a thin coating onto a simple frame. Because grancrete binds to many surfaces, the frame can be made from wood, metal, or even polystyrene or woven matting. When it hardens, 20 minutes later, the grancrete structure is twice as strong as traditional concrete, and it is durable, fire-resistant, waterproof and non-toxic—more than can be said for most of the poor's housing. Salt does not corrode it, so it is suitable for use in coastal areas and its insulating properties mean that it can be used both in hot and cold climates. It should also be strong enough to withstand hurricane-force winds.

"Jim Paul, Grancrete's chairman, reckons that a team of two can build a simple house in two days. All in all, he estimates that low-cost housing can be made for $12 to $15 per square foot. Grancrete opened its first full-scale production plant this summer. So far, it has performed proof-of-concept demonstrations in Venezuela and Panama, and is preparing for more in Mexico, Canada, Argentina and America."