ISU Researchers Examine Heated Pavement


Iowa State University engineers are moving onto the second stage of testing—in a more intense real-world environment—of heated pavement, which will undergo the stress of heavy truck traffic.

The technology features electrically conductive concrete, and this latest round of testing also incorporates a concrete mix that meets highway specifications. While research began in 2015, tests started in the fall of 2016, with the installation of two 15-by-13.5-foot test slabs at the Des Moines International Airport. Halil Ceylan—an Iowa State professor of civil, construction and environmental engineering, the director of the Institute for Transportation’s Program for Sustainable Pavement Engineering and Research—is spearheading the project.

Heated Pavement at ISU

The special concrete contains 1.25 percent carbon fiber, and the fibers are 1/4-inch long and about 7 millionths of a meter across by volume, conducting electricity supplied by the electrodes. Heat comes from electrical resistance in the fibers.

In 2016, with the help of a $2.2 million grant from Federal Aviation Administration’s Center of Excellence Partnership to Enhance General Aviation Safety, Accessibility and Sustainability, the team installed the aforementioned test slabs next to the airport hangar. The slabs melted snow and ice even during the coldest periods.

This prompted a bigger test inside a busy entrance to the Iowa Department of Transportation campus: This installation featured 10 heated slabs totaling 75 feet long and 24 feet wide, featuring five different configurations of electrodes, which accounts for different diameters and shapes, as well as spacing of the stainless-steel rods and bars.

When the first load of electrically conductive concrete was poured at the Iowa DOT, a crewmember was able to use a wide levelling float across the test section’s width. Ceylan noted that this was an advantage to this kind of technology: The shovels, spreaders and other equipment used were all the same kind of equipment, except for the addition of carbon fiber to the concrete.

“The closer the electrodes are to each other, the more energy there is,” Ceylan said. “And larger electrodes are able to pump more energy.”

Next Round of Testing

In this latest round of testing, the slabs will be carrying traffic. Ceylan added: “There is a lot of heavy traffic. This will help us learn about pavement performance under heavy truck loads, as well as heating performance and the cost to heat.”

Though heated pavement technology has already resulted in four patent applications, Ceylan looks forward to what his team can learn, calling the new installation “a much richer test section than in Des Moines.”

The installation required the placement of a 7-inch base layer of standard highway concrete, then the attachment of stainless-steel electrodes to the base layer, as well as the addition of sensors and probes to the same layer. Then, finally, 3 inches of the electrically conductive concrete were placed on top. Ceylan noted that the technology would most likely be suitable for small stretches of highway, such as bridge decks that are prone to icing.

Funding assistance, a $360,000 grant, came from the Iowa Highway Research Board and the Iowa DOT.


Tagged categories: Colleges and Universities; Infrastructure; NA; North America; Program/Project Management; Research and development; Roads/Highways

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