Let it snow…

Electrically conductive concrete could melt snow on roads without chemicals!

The idea is already economically feasible in driveways and sidewalks, but the idea of having open roads during a snow storm seems very attractive and challenging at the same time!

Furthermore, a snowmelt system may extend concrete’s or asphalt’s life, as there is no use of salts and chemicals which can lead to concrete corrosion or salt pollution issues (especially near waterways). Actually, it is said that this technology is more cost-effective in the long run than continual salt dumping and removal and because it extends concrete’s life, less waste is produced.

Researchers from University of Nebraska-Lincoln have created a special mix of concrete which is partially (20%) consisting of steel shavings and carbon particles, giving enough conductivity to the mix to melt ice and snow. And due to the fact that those are by-products of coal and steel industry, the cost is reduced by 60% in comparison to former trials according to Professor of civil engineering Chris Tuan. The idea is to have a regular concrete mixture provide the basic structure of an installation with the special conductive concrete forming a surface layer on top, in order to minimize the amount of concrete that needs to be heated.

 Watch Conductive concrete melt snow

A four-hour time-lapse video shows the conductive concrete melting fresh snow from its surface during a winter storm in Omaha, Nebraska, in December 2015. (CHRIS TUAN AND LIM NGUYEN, UNIVERSITY OF NEBRASKA-LINCOLN)

Federal Aviation Administration funds the research, and is planning to use this product into tarmacs, reducing weather-related delays. As weird as it may sound, the interest for de-icing via this technology is on the tarmacs which are difficult to be cleared due to constant activity and their geometry. Runways on the other hand can easily be treated with big snowplows.

Roca Spur Bridge-an applied example

The Roca Spur Bridge (south of Lincoln, Nebraska) was an ideal testing scenario, as bridges, unlike other road surfaces, are notoriously quick to freeze because they're exposed to the air on both the top and bottom surfaces. The bridge is 45m (150ft) long and three lanes wide and in 2002, Tuan and the Nebraska Department of Roads turned it into the world's first bridge to incorporate conductive concrete. The overlay is broken into 52 cross-bridge slabs, each of which can be energized individually. A controller applies power to the slabs in a sequential manner, reducing the peak power requirements. The slabs are energized with 208V when surface temperatures drop below 40^oF, and power is cut off at temperatures over 55^oF. The tests generally went well, Tuan says as the results show that a 3-day storm de-icing typically cost $250, several times less than a truckload of chemicals.

But apart from its use on bridges, airports, sidewalks, pedestrian crossings or other locations you always get ice, this technology has also another side benefit. Replacing the limestone and sand with magnetite in the blend, the mix manages to shield against electromagnetic waves. A concrete with this characteristic could be used in cellphone communication blocking in high-security buildings.

The technology seems promising, however there are still liability issues and cost hurdles to overcome. For sure it is worth it to give it a chance…