- Associated Press - Sunday, February 7, 2016

OMAHA, Neb. (AP) - Imagine if battling slick and dangerous road conditions caused by snowstorms could be as easy as flipping a switch.

Chris Tuan, a professor of civil engineering for the University of Nebraska at the Peter Kiewit Institute, has been perfecting an electrically semiconductive concrete over the past 20 years.

The mixture includes a 20 percent mix of steel fibers, shavings and carbon added to a traditional concrete mix. Steel reinforcing bars serve as the conductor, and once electricity is added, the concrete heats to 35 to 40 degrees - just enough to melt the ice and snow.

In a demonstration outside the Peter Kiewit Institute, Tuan threw a handful of snow on a small area of fenced-in concrete. Within about 90 seconds, it melted.

Mitchell Kowalewski, Tuan’s graduate research assistant, sees myriad future benefits.

“You’re no longer having the city people out to de-ice it, you’re no longer having to shovel it, and in industrial applications, you can use this on loading dock areas so you’re no longer having injury on the job,” Kowalewski said. “It’ll decongest and make areas safer.”

Tuan said the concrete is likely too expensive to be universally applied. But his hope is that accident-prone roads - bridges, interstate exit ramps and intersections - will eventually all be paved with the mix. He also envisions an Internet-connected system that can monitor weather conditions and turn on automatically prior to a winter storm.

For now, the concrete can’t be used in public spaces. Anything exposed and electrified above 48 volts - much less than the 208 volts used in Tuan’s concrete - is considered high voltage and is not allowed. Federal law will have to be rewritten to change that.

Although the concrete is more expensive - about $180 more per cubic yard than regular concrete - he said the long-term benefits pay off.

“You have to compare apple with apple,” Tuan told the Omaha World-Herald (https://bit.ly/1UNXmZ1 ). “Compare $300 versus $120 - $300 you have a de-icing function, and $120 you don’t have anything, and you have to spray salt or de-icing chemicals and that degrades your concrete.”

Tuan said traditional concrete needs to be replaced every five years or so. Without chemical use, the electric concrete lasts much longer, with fewer potholes. His concrete is also maintenance-free, because the power cords and conductive rods are encased in the concrete and not exposed to the elements.

This concept is different from the hydraulic system often used for residential driveways, Tuan said. Traditionally, heating fluids, such as antifreeze or warm water, are pumped through pipes embedded in the concrete, a method Tuan said is expensive and wastes more energy.

The Federal Aviation Administration is monitoring Tuan’s work and is considering integrating the technology into airport tarmacs.

However, he said the FAA isn’t interested in runways; those can be cleared in a matter of minutes with plows. The concrete would be used in the fenced-off luggage and food-loading areas near planes, which are often the cause of flight delays.

The method itself is safe, Tuan said, but each project would require individual specifications to ensure safety. He said conductivity, the spacing of the electrodes and the size and thickness of the slab of concrete are all factors to consider. In warmer weather, the electricity would simply be shut off, the concrete back to normal until the next snowfall.

The de-icing concrete has already been tested in the real world. In 2003, Tuan installed 52 slabs of the concrete onto the 150-foot Roca spur bridge 15 miles south of Lincoln. The five-year test showed the method was workable. Melting snow on the bridge cost about $250 per major snowstorm.

In 2013 Tuan also implemented his concrete on ramps in China. He recently installed a private driveway in Regency using the legally allowed 48-volt limit, which is less energy efficient.

“If the government or if insurance agencies approve this technology, then everybody can use it,” Tuan said. “But right now, it’s almost cost prohibitive.”


Information from: Omaha World-Herald, https://www.omaha.com



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