Research Highlights

Pod to Pavement

Checkoff investments further soy-based polymer research and testing

By Bethany Baratta, Iowa Soybean Association senior writer

Researchers at Iowa State University (ISU) spent about eight years researching how soybean oil could replace petroleum as a binding agent in creating asphalt. Now, thanks to years of research and investments from the Iowa Soybean Association (ISA) and the United Soybean Board (USB), the product is a part of highways and parking lots in Iowa and in other states. 

With additional demonstration projects in queue, the pod-to-pavement project could be spread even wider. 

“A two-lane highway would use about 70 bushels of soybeans per mile if it all works out,” says ISA District 2 Director Casey Schlichting of Clear Lake. 

The product is part of demonstration projects after years of research at ISU’s Bio-Polymer Processing Facility at the BioCentury Research Farm.  

To go from very small quantities in tiny, half-liter bottles to 12, 50-gallon drums and eventually tanker trucks that deliver the product to be used in highway projects, is a good feeling, say Austin Hohmann and Paul Ledtje. They oversee the bio-based polymer processing facility and asphalt lab. Their team helped formulate the right mix of polymers to make the product just right — not too thin, not too thick.  

Investments pay off 

Rolland Schnell was serving on the ISA board of directors when ISA and USB each pledged $125,000 for bio- based polymer research at ISU. Now, more than $13 million in private, state and federal funds have been leveraged to bring bio-based polymers to market. 

The investments seem to be paying off, says Schnell, who farms near Newton. 

“It has the potential of using a significant amount of soybean oil. If we can further utilize soybean oil here at home, it’s not only good for us as farmers, but also for livestock farmers as it lessens the price of soybean meal,” Schnell says.  

Bio-based polymer is a good alternative to petroleum-based products, says Chris Williams, director of the Asphalt Materials and Pavements Program at ISU. 

“When you’re dealing with the supply chain, people like to have some pricing stability. Soy has a lot lower price volatility than crude petroleum,” Williams says. 

Petroleum-based polymers cost between $2 and $4 per pound and contain butadiene, which is largely imported from Asia. Soy-based alternatives cost around $1 per pound and are grown and sourced domestically.  

Scaling up production as other states adopt the product lessens the cost and makes the soy-based polymer an attractive choice to companies like Bituminous Materials and Supply. 

The company’s plant in Tama was one of the first to include the soy polymer in a recent blending project for Grimes Asphalt. After polymers were mixed at the plant in Tama, the binding product was trucked to Grimes Paving and offloaded into an asphalt tank. The asphalt was then used in a demo project on a highway near the Southeast Polk High School.  

The polymer product was sufficient for Rod Boldt, the plant manager at Bituminous Materials and Supply in Tama who oversaw the mixing of the polymers.  

Boldt says typically polymers are pelletized and require a high heat treatment before the product can be added to asphalt. In this case, 12, 50-gallon barrels were transferred into a tanker truck to mix with other polymers. 

 “If this will work for a polymer, it would be a good deal,” he says. “If we can run it through this way (liquid), that saves us time and money.” 

Another demonstration project used the polymer blend as part of a resurfacing project at ISU’s BioCentury Research Farm. 

More projects are slated for Missouri and Alabama yet this year, as weather will allow. Other projects are on track for Minnesota, Montana, Nebraska, South Dakota and Texas in 2020. 

Williams says demonstration projects are another step toward commercializing the product. 

“We would like to start seeing some commercial sales next year,” he says. “But demo projects are important for getting the knowledge out there on the projects and de-risking the technologies to go to the commercialization phase.”  

It’s another step forward for ISU researchers who have dedicated years to the project, like Hohmann, whose work on the chemistry side of the project propelled it to the demonstration phase. 

“The first time this went into asphalt I had tears running down my face,” Hohmann says.  

Farmers are equally excited about the project and its future to create demand for their soybeans. 

“It’s good to see a product come to fruition, which first comes out of your fields,” Schlichting says.  

ISA Communications Specialist Lauren Houska contributed to this story. 

Published: Jan 1, 1970