Engineers have experimented for years with making road infrastructure more sustainable, such as by using recycled tire rubber and crushed glass as filler. Tech developments also have allowed asphalt to be recycled and repurposed. Now, University of Nebraska-Lincoln engineers are studying the effectiveness of using corn and soybean oil, instead of petroleum oil, in recycled asphalt pavement, or RAP. 

RAP materials removed from roadways traditionally are combined with some new materials and a recycling agent to create hot mix asphalt. Hamzeh Haghshenas Fatmehsari, research assistant professor of civil and environmental engineering, knew that using corn and soybean oil instead of crude oil is feasible for short-term asphalt recycling. His research team is trying to prove the long-term performance of RAP containing these oils.

The researchers hope to increase RAP content in Nebraska roadways both for environmental purposes and cost-effectiveness. Already, from 2008 to 2019, the Nebraska Department of Transportation used an average of 39% RAP in its asphalt road paving mixes, which saved about $34 million annually. 

This research could validate a new market for soybean and corn oils. The feedstocks for these oils are grown locally in abundance.

“We are finding ways to increase demand for our soybean oil while supporting a method that decreases our environmental impact and benefits taxpayers and those that utilize and drive on asphalt pavements,” Nathan Dorn, a farmer and chair of the Nebraska Soybean Board’s research committee, said in a news release.