From Phys.org
De-icing concrete could improve roadway safety, guard against corporate espionage
…By replacing the limestone and sand typically used in concrete with a mineral called magnetite, Tuan has shown that the mixture can also shield against electromagnetic waves. The electromagnetic spectrum includes the radiofrequency waves transmitted and received by cellphones, which Tuan said could make the concrete mixture useful to those concerned about becoming targets of industrial espionage.
Using the magnetite-embedded concrete, Tuan and his colleagues have built a small structure in their laboratory that demonstrates the material’s shielding capabilities.
“We invite parties that are interested in the technology to go in there and try to use their cellphones,” said Tuan, who has patented his design through NUtech Ventures. “And they always receive a no-service message.”
A slab of conductive concrete demonstrates its de-icing capability outside the Peter Kiewit Institute in Omaha during a winter storm in December 2015. The concrete carries just enough current to melt ice while remaining safe to the touch.
…A 200-square-foot slab of seemingly ordinary concrete sits just outside the Peter Kiewit Institute as snowflakes begin parachuting toward Omaha on a frigid afternoon in late December.
The snow accumulates on the grass surrounding the slab and initially clings to the concrete, too. But as the minutes pass and the snow begins melting from only its surface, the slab reveals its secret: Like razors, stoves and guitars before it, this concrete has gone electric.
Its designer, UNL professor of civil engineering Chris Tuan, has added a pinch of steel shavings and a dash of carbon particles to a recipe that has literally been set in concrete for centuries. Though the newest ingredients constitute just 20 percent of Tuan’s otherwise standard concrete mixture, they conduct enough electricity to melt ice and snow in the worst winter storms while remaining safe to the touch…