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Morgan Sanger at the Research in the Rotunda event
April 30, 2018

Rethinking resurfacing: Students dig into alternative approach

Written By: Peter Jurich

Geological engineering undergraduates Morgan Sanger, Renee Olley and Tyler Klink are trying to make modern construction methods more sustainable and beneficial to the earth.

They conduct research through the Recycled Materials Resource Center and are focusing on the environmental benefits of cold-in-place recycling, a method of highway resurfacing.

“It’s an alternative method that’s been around for more than a decade and is used for its recognized economic benefits,” Sanger explains. “Conventionally, the asphalt highway is reconstructed with a method called mill-and-overlay, where they mill the existing roadway, haul it to an asphalt plant, bring in new material and then lay that material down. Cold-in-place recycling does the milling, but instead of hauling it away, you mix it with something else at the site and lay it back down.”

As a result, road builders use fewer new materials and spend less on transporting materials to a job site.

Although the method sounds like a win-win, its environmental benefit has not yet been quantified, says Sanger. In comparing the cold-in-place technique with the traditional mill-and-overlay process, the students found the former saves 20 percent in energy consumption, water consumption and carbon dioxide emissions.

“We compared the different stages of each method and found that the cold-in-place recycling was much more environmentally friendly, because even though you do use more energy to do the onsite mixing and crushing, this is only a small percentage of the energy you would use in mining and transporting and all this extra virgin aggregate,” says Olley.

Cold-in-place recycling also cuts in half the cost of the mill-and-overlay process.

The student researchers worked with the Wisconsin Department of Transportation to collect data from 68 miles of roadwork. Their advisors, Grainger Institute for Engineering Assistant Director for New Technology Directions Angela Pakes and Civil and Environmental Engineering Professor Emeritus Tuncer Edil, presented the results in January 2018 at the annual Transportation Research Board Conference in Washington, D.C.

Sanger, Olley and Klink also took part in the 15th annual Research in the Rotunda event in April 2018 at the Wisconsin State Capitol, allowing them to share their work with state legislators, officials and others.

Based on their research, the three students developed a curriculum and, in spring 2017, taught an engineering class called “Eva the Engineer” to middle school girls. In the program, sixth- through eighth-grade girls had a chance to learn about engineering concepts like concrete mixtures, waste management and water treatment.

“It was a chance to develop lesson plans that I never experienced in middle school myself,” Klink says. “It was more in-depth, I felt, than a normal science class.”