InTrans / Apr 02, 2020

Heated pavement tests advancing

On a frigid February morning in 2019, pavement slabs on the Iowa Department of Transportation (DOT) campus began to heat up, and soon steam started to rise. Everything was going exactly as Halil Ceylan had expected.

Ceylan, the director of the Program for Sustainable Pavement Engineering and Research (PROSPER), has been researching the potential and the practicalities of electrically conductive heated pavements since 2013.

The tests have scaled up from laboratory slabs in 2015 to two, 15-by-13.5-foot test slabs at the Des Moines International Airport in 2016, to the newly poured 10 heated slabs totaling 75 feet long and 24 feet wide at the Iowa DOT campus. Read more about the project here.

While the slabs at the Iowa DOT were poured in late 2018, Ceylan tested their success a few months later when the Iowa winter was in full chill. As he looked at the ice melting on the concrete, Ceylan said it was no surprise that the new and smarter system was already working well.

Unlike the earlier airport test slabs, which were located to avoid most airport traffic, the new test slabs carry traffic and feature a concrete mix that meets highway specifications.

“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,” Ceylan said. “This is a much richer test section than in Des Moines. It’s more complex. We’ll learn a lot more here.”

Ceylan’s initial project was the first for the Federal Aviation Administration’s Partnership to Enhance General Aviation Safety, Accessibility, and Sustainability (PEGASAS). His current project is sponsored by the Iowa DOT and Iowa Highway Research Board and is expected to continue through spring 2020.

The primary objective of the current research is to do a full-scale field demonstration of the electrically conductive concrete technology and its efficient deicing benefits for Iowa city and county roadways and state highways. Expected benefits from this research include the following:

  • A cost-effective methodology for producing electrically conductive concrete for Iowa pavement snow and ice removal applications
  • An understanding of electrically conductive concrete at different scales (cement paste, mortar, and concrete) and their properties
  • Detailed insights into the challenges and issues faced during the full-scale construction of electrically conductive concrete

Though the concrete can be poured and constructed using typical paving equipment, the process is slightly more complicated than building a typical roadway.

The Iowa State engineers have developed the special concrete containing 1.25 percent carbon fiber by volume. The tiny fibers—just a quarter inch long and about 7 millionths of a meter across—conduct the electricity supplied by the electrodes, but there’s some electrical resistance in the fibers, and that creates heat throughout the pavement. The technology has already produced four patent applications.