December 16, 2019

Researchers develop asphalt with soybean oil

Iowa State University engineering professors have developed an asphalt paving material that contains soybean oil. The substance is more environmentally friendly than traditional asphalt and costs less, according to researchers.

The engineers who worked on the project were Christopher Williams, professor of civil, construction and environmental engineering, and Eric Cochran, professor of chemical and biological engineering. Cochran said the construction of the Research Farm manufacturing the material began in 2014 and has produced over ten tons of material over the operating season.

“We start with high oleic soybean oil; there are several epoxidation facilities throughout the country that are underutilized,” Cochran said. “Epoxidized high oleic soybean oil gives those epoxidation facilities a new purpose and new potential for the companies that own them to get more value out of them. We can make soybean-based rubber that can be formulated into non-volatile organic solvents that can be handled without respirators.” Williams said the new compound is friendly to the environment and not as dangerous as its alternative, butadiene.

Crude oil refiners extract asphalt in the refining process after removing other valuable materials. The remaining asphalt is often hard and brittle so it requires lubricants and fuels extracted earlier in the process to be bought back and added to the asphalt. “One aspect of how soybean oil based rubbers are valuable is we found we can, very cost effectively, revitalize low quality hard and brittle asphalts,” Cochran said.

Williams estimates the soybean-derived biopolymer based asphalt is $3,000 cheaper per lane mile than traditional asphalts.

Vegetable oils could bring many advantages to roadbuilding. Already in 2004 Dura Vermeer used rapeseed oil to partially replace fossil bitumen. The new asphalt Ecopave XL claims to reduce energy cost by lowering the working temperature from 160-170ºC to 125ºC and since degeneration occurs much slower compared to the conventional fossil bitumen based asphalt the lifespan is longer. So replacement becomes necessary after a much longer period.

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Last modified: December 18, 2019