Iowa State researchers develop soybean oil-infused asphalt


Design by Maria Albers

Two Iowa State engineer professors, Christopher Williams and Eric Cochran, worked on a paving project of a parking lot adjacent to the BioCentury Research Farm. The lot was paved with asphalt created from newly developed soybean-derived biopolymers.

Quinn Vandenberg

Two Iowa State engineering professors presented their work in developing biopolymers from soybean oil for asphalt production Monday at an open house.

The open house was hosted at Iowa State’s BioCentury Research Farm after a paving with the soy project took place. A half acre parking lot adjacent to the Research Farm was paved with asphalt created from newly developed soybean-derived biopolymers.

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.

Those who attended the open house included Williams, Cochran, representatives from the Iowa Soybean Association, United Soybean Board, Asphalt Paving Association of Iowa and the Iowa State University Research Foundation.

Cochran said in early 2013 the team met with Iowa Soybean Association and reported they could manufacture new rubber with soybean oil. This led to additional research into the chemistry of new high oleic soybeans.

“We very quickly discovered that there were really important advantages to that changing of the oil chemistry that enables [us] to make a soybean-based rubber with greater elastic properties and really able to improve the performance of asphalt pavements,” Cochran said.

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.

Several areas were considered for commercial applications of the new product and asphalt modification provided them with the most potential, according to Cochran.

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.

Asphalt containing soybean-derived biopolymers can also increase the recycling factor of traditional asphalts by at least two, Cochran said.

“In 2017 there were 300 million tons of asphalt pavements placed throughout the United States,” Cochran said. “And about 60 million tons of that paving opportunity was biopolymer-modified pavement requiring about 350 million pounds of biopolymer.”

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

Research from the open house presentation reported one pound of the soybean-derived biopolymers costs $0.92 per pound compared to the previously used styrene-butadiene product at $1.05 per pound.

The new product has to undergo testing to ensure it is not a risk to the government, Williams said. Part of this involves a test track where the Department of Transportation for 30 different states participates in research, testing the performance of the biopolymers.

“We’re not asking people to modify their process — modify their equipment — to handle this material, and that’s really important,” Williams said.

Williams visited the test track three weeks prior to the event and said it had four million truck loadings already on the test section.

“It’s performing exceptionally well; there’s no signs of cracking,” Williams said. “When we design roadways in Iowa, high volume roads are anything above three million [equivalent single axle load], so we’ve already exceeded that barrier of performance.”

Williams said in the near future the track will undergo testing to find its performance under loads approaching that of I-35’s traffic over a twenty year period in a much shorter time.

Rolland Schnell, member of the Iowa Soybean Association and farmer from Newton, Iowa, spoke at the open house event and highlighted the product’s benefits to soybean farmers.

“I believe that our soybean product is unique,” Schnell said. “We not only feed and fuel, but now we pave the whole world. Investing in new uses, like the soy based asphalt, gives my soybeans more value and increases the demand which is critical at this time.”

Schnell addressed soybean farmers directly and said this project is a perfect example of how money from United Soybean Board’s check off dollars are used to fund research that increases the value of their product.

Williams said check off dollars are a tax placed on the sale of soybeans that goes into a fund managed by the United States Department of Agriculture. The money pays for marketing, advertising and research into future uses of the product, which financed a large portion of the project.

David Sanders, Greenwood Department chair and professor of civil, construction and environmental engineering, opened the presentation at the open house. Sanders spoke on the impact of the product’s research to the university.

“I think one of the things that we pride ourselves on at Iowa State is the merger of fundamental research and applied research and how we can impact the communities around us,” Sanders said. “This [Research Farm] that [Williams] and [Cochran] have been working on is definitely a great example of that.”

Sanders said the Research Farm was commissioned in 2015 and is now capable of producing approximately one ton of product per day.

Williams and Cochran both said they were thankful for the team they had throughout the development process in their presentations at the open house.

“There have been so many times where we didn’t understand how we were going to get through the next barrier,” Cochran said. “Unrelenting optimism and ‘cannot fail’ attitude has been what’s carried us through all this.”

Williams said several staff members of the project had previously worked on it as students, forgoing potentially more money in other careers to see the technology develop.

“Between our two groups there’s been at least ten Ph.D. students that have touched this project in one way or another, [and] in the order of 50 to 60 undergrads over the last eight years,” Cochran said.

Cochran said the majority of undergraduates working with him on the project are pursuing degrees in chemical engineering with some in chemistry and material science and engineering. Williams primarily works with civil engineering students.

Along with the test track in Opelika, Alabama, and parking lot at the BioCentury Research Farm, the soybean-derived biopolymer asphalt has also been used near Southeast Polk High School.

The asphalt is planned to be used in states such as South Dakota, Nebraska and Missouri, according to Williams.

“We have to convince a contractor that it’s interesting,” Cochran said. “We’ve got to convince a supplier of asphalt that it’s interesting and the Department of Transportation. It’s a lot of coordination.”