Four hour time-lapse showing conductive concrete melting fresh snow. (Video courtesy of Chris Tuan/Lim Nguyen/University of Nebraska-Lincoln.)

Conductive concrete could be coming soon to roads and airports near you, if current testing of the material concludes successfully. 

The concrete has steel shavings and carbon added in specific amounts, about 20 percent of the mix of regular concrete, which serves to make it more conductive than normal. 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.  This minimizes the amount of concrete that needs to be heated. 

When the system detects freezing surface temperatures, it responds and raises the concrete’s surface temperature above the melting point of snow and ice.

So far, this has been spectacularly successful on a long running test.  One of the testing scenarios was on bridges, which unlike other road surfaces are notoriously quick to freeze because they're exposed to the air on both the top and bottom surfaces. 

Conductive Concrete Field Test

The Roca Spur Bridge south of Lincoln Nebraska is one hundred fifty feet long and three lanes wide.  Christopher Tuan, professor of civil engineering at the University of Nebraska-Lincoln, used his new conductive concrete to deposit a 4-inch overlay on the bridge.  The overlay is broken into 52 cross-bridge slabs, each of which can be energized individually.  In this case, the slabs are heavily instrumented for the study.

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 40F, and power is cut off at temperatures over 55F.  The thermal mass allows carry-through between the energized periods while all the slabs are being cycled. 

In the tests, an average power density of 42W/sqft kept the ice and snow at bay during storms.  The total power consumption for the bridge is about 1000 kWhr per day during a snow storm.

The cost of the power to operate this system is only a fraction of the cost for several tons of deicing chemicals that would normally be needed to fend off a storm's icy assault.  Professor Tuan expects that his solution will be welcomed in road locations at a high risk for ice buildup, such as off-ramps, bridges, pedestrian crossings, problematic intersections and sidewalks.

Conductive Concrete Tarmacs?

This new direction in concrete development has also attracted the attention of the FAA, which has commissioned a test of the conductive concrete this winter running through March.

If the test is successful, the FAA plans to apply the concrete to a major airport's tarmac area. Tarmacs are often more problematic than the runways because they are difficult to plow owing to constant activity and geometry. 

Conductive concrete offers us much in reducing chemicals and salt pollution issues, especially when the deicing materials have to be applied near water ways.

For more information, visit the University of Nebraska-Lincoln website.