May 9, 1997
British develop concrete that conducts electricity
By LUCY BODILLY
Airplane runways, porches and driveways that de-ice themselves are just a few of the potential uses for a new concrete product that conducts electricity.
First developed for the British military, the product was initially to build walls that would stop foreign spies trying to study the electromagnetic radiation emitted by computer equipment. Called Faraday cages, the electric current flowing through the concrete acts like an anti-bugging device, according to David Barker, financial director of Elfinco, the British company marketing the product.
The concrete is comprised of normal cement, but the aggregate is replaced by metal balls that conduct electricity. The final product has the same flow rate as traditional concrete and cures in 28 days, Barker said. To date, Elfinco has only constructed Faraday cages with the product, but is now pushing commercial uses.
Another possible use is home and commercial heating applications. The concrete heats up when the electricity passes through it and is 80 percent more efficient than traditional electric heating systems because little energy is lost during the process, Barker said. A Swedish supplier of gradient heating is exploring that use. For this use, the concrete is poured into blocks and connected using another Elfinco product, electro conductive glue. They can operate on all power supplies. The blocks connect to the power supply through metal buss bars glued to each end of the block. Temperatures up to 400 degrees Celsius are possible.
The company's glue is electrically conductive and maintains its integrity at temperatures up to 1,000 degrees Celsius. The glue could be adapted for underwater use, or to make couplings.
A more obscure use for conductive concrete is an antennae. "Most antennae are very ugly, but these look like part of the building," Barker said. "That is good from a military or architectural standpoint." The use is ideal for areas with a large network of slot antennae. Since a change in temperature is detectable, the product could also be used for a fire alarm.
The product is more expensive than traditional concrete, but could prove a cost savings in the long run. "If we replace the steel usually used in the Faraday cages with conductive concrete, the savings is about 80 percent," Barker said.
Elfinco has been ready to market the product since 1994. "We are trying to get the product licensed," said Barker. So far, companies in Europe and the U.S. have shown interest.
Elfinco officials would like to see manufacturing plants that could produce the aggregate substitute. Currently, interested parties can have the material shipped from England. Or a distributorship could be formed, with the supply coming from the main plant.
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