Most people don’t think a lot about roads or other asphalt surfaces they use. They’re just thinking about getting to work, school, or home or parking their car.
When Haifang Wen looks at a road, however, he sees a whole life cycle.
“My research group is working toward sustainable infrastructure. Recycled roadway, sidewalk, shingles, buildings, cooking oil, and steel slag can all work together in a system to build renewable roadways,” said Wen, who is a professor in the Department of Civil and Environmental Engineering.
Wen is the director of the Washington Center for Asphalt Technology, a partnership between the Washington State Department of Transportation, the Washington Asphalt Paving Association, and WSU.
Two major projects Wen is leading evaluate the effectiveness of recycled asphalt taken from old roadways and shingles. Currently, about 100 million tons of roadway and 11 million tons of shingles are sent to landfills every year. With Wen’s research, the asphalt in those materials is extracted and mixed with traditional asphalt. Using this method can reduce waste and the use of crude oil that currently makes up asphalt.
While the asphalt from those shingles and roads would be mixed with traditional asphalt, Wen is also doing research on the development of bioasphalt, a material made of cooking oil left over in McDonald’s and other restaurants’ deep fat fryers.
“Traditional asphalt is made from crude oil, which is expensive and environmentally harmful. Cooking oil is one-third the price of crude oil,” Wen said. Plus, cooking oil is a harmful waste product, so finding a use for it also benefits the environment.
Asphalt is not the only material that makes up a roadway, however. The thick substance must be heated and mixed with aggregate in order to harden into the material we drive and walk over.
Samples of roadway used for testing.
“Asphalt now has to be heated to 300 degrees Fahrenheit in order to combine with the aggregate. At that temperature the asphalt produces a toxic blue smoke,” Wen said.
So he is working with a team on new technology to develop a warm mix asphalt, one that only has to be heated to 200 or 230 degrees. The warm mix gives off fewer fumes, meaning it saves energy and the health of the people who work with it.
Wen’s team is also testing alternative aggregate materials, such as recycled side- walks and steel slag from mills and recycled buildings. Using those materials would reduce the environmental impacts of resource extraction from mountains and quarries.
In a lab in the basement of Sloan, Wen and his research team test the different forms of asphalt and aggregate, comparing them to traditional roadways.
“So far, most of our samples perform as well as samples of traditional road,” Wen said.
As his research moves forward, he will begin testing the materials on actual roadways, and eventually create samples that are made entirely of recycled materials.
These research projects are funded by and in collaboration with a variety of organizations, including the National Cooperative Highway Research Program, National Science Foundation, King County, Washington State Department of Transportation, Idaho Transportation Department, University Transportation Center, and U.S. Department of Transportation.