Cold, December weather often freezes sidewalks and damages asphalt on paths and streets.

Christopher Williams, associate professor of civil, construction and environmental engineering, is head of a project that is testing bio-oil on asphalt in order to improve hot and cold weather performance of pavements. Williams has been working on the project for four years.

“We fractionate the bio-oil in five or six different fractions,” Williams said. “Those different fractions have different compositions.”

Williams and a research group have been working to test their data.

“We produced asphalt that we heated up in a high temperature,” Williams said.

The asphalt goes through a treatment process to ensure no water is in the asphalt once it is made.

“Two fractions that come out of the bio-oil are put through a heat treatment, which dries out the water,” Williams said. “Then blend it in with asphalt or we can take a polyethylene, which stabilizes and provides low-temperature cracking.”

An alternative to the heat treatment process is to use petroleum as a replacement for the asphalt. These studies have been conducted in a lab to see if they are able to replace asphalt.

Petroleum is another alternative. It can be used either as a partial replacement or a full replacement for the asphalt, Williams said.

Williams and his group will receive a sub-award through the Power Fund Project. Avello Bioenergy Inc. who Williams is working with, received a $2.5 million grant to develop bioasphalt as well as other bioproducts.

The current price of asphalt is about $400 per ton, or 2,000 pounds.

“Bio-asphalt can be produced at a lesser price,” Williams said. “Asphalt comes from crude petroleum. If we as a country want to be more energy dependent, it means we’re going to have less asphalt available.”

In the United States, 90 percent of paved roads utilize asphalt.

“Asphalt is a maintenance application for sealing cracks and making more quality roadways,” Williams said.

Since asphalt is what helps build our roadways, it, of course, is an important element of creating a way for transportation services, which are heavily dependent on roadway systems.

“Around 65 to 68 percent of our [gross domestic product] relies on our transportation systems,” Williams said. “Vast majority is highway-based.”

Williams hopes to use bio-asphalt material as a way to create more jobs as well as a way for paving a way to a cleaner environment.

“It helps create a cleaner environment, and we become less dependent on foreign energy sources like petroleum,” Williams said.