Better Performance & 25% Lower Paving Costs

Soy’s success in construction and paving won the American Chemical Society (ACS) 2021 Cooperative Research Award in Polymer Science and Engineering. ACS honored the Iowa State University (ISU) research on April 15 and featured a lecture “Putting soy-based thermoplastics to work in the construction industry.”

During its spring meeting, ACS recognized Iowa State University Professors Eric Cochran and R. Christopher Williams and their industrial partner Donald Sjogren of Seneca Petroleum Company. The United Soybean Board as well as the Iowa Soybean Association contributed to the research and the debut of the cost-effective asphalt biobased polymer in 2019. ISU has demonstrated it in multiple municipalities.

“The soy-based polymer improves performance while it also promotes environmental stewardship—not only because it’s biobased, but also because you’re able to reuse more recycled asphalt content when you’re producing these roads,” says Cochran. “Importantly, it is cost competitive with asphalt paving materials that depend on foreign oil instead of U.S.-grown soybeans.”

“It’s been tested by transportation departments in 30 states with more than four million truck loadings, and we’re confident it’s high quality,” adds Williams.  “Along with that, this technology could reduce paving costs by 25%. That’s a very conservative estimate.”

After nine years of development, the ISU research team is about to launch a commercial process for a high-oleic soy oil polymer that can replace petroleum-based polymers in asphalt paving. They found the biobased binding agent is an economical, efficient, and sustainable alternative to highly volatile and expensive chemicals currently used in asphalt pavers with the potential to open a new, large market for soybean growers.

Each mile of a typical four-lane highway would use the equivalent oil from approximately 1,500 bushels of high-oleic soybeans and an additional 1,500 bushels of commodity beans, calculates Cochran.

The high-oleic soybean oil polymer, known as (polyacrylated epoxidized high oleic soybean oil), or PAEHOSO, is a rubbery polymer that provides crack and rut resistance in pavements formulated with high-recycled content and other low-cost asphalt sources. PAEHOSO can be produced in soy-based rejuvenating oils that further aid in the rehabilitation of recycled pavements.

The polymer/oil cement, known as “BioMAG,” is manufactured at nearly 100% atom efficiency without the need for organic solvent or polymer finishing steps. To date, the research group has produced 50 tons of BioMAG and used it in demonstration paving projects in several states throughout the U.S. The first full-scale commercial batch is planned for production this spring.

“BioMAG has proven itself in the field over and over as a contractor-friendly means to sustainable heavily trafficked pavements with high recycled content,” Cochran said. He reported demonstrations have already been conducted in Opelika, Ala., Janesville, Wis., St. Joseph, MO, Brainerd, Minn., Indianapolis, Ind., Chicago, Ill, Shutesbury, Mass., and Grimes, Iowa. Additional demonstrations are planned in Alabama, Texas, South Dakota, Nebraska, Indiana, and Missouri.

USB has also supported a three-year product evaluation at the National Center for Asphalt Technology at Auburn University in Alabama.

As an additional benefit from these processes, a substance known as polyacrylated glycerol (PAG) can be manufactured from crude glycerol as a water-soluble adhesive that displaces polymeric diphenylmethane diisocyanate, a chemical substance, in wood composite. The team has shown that PAG adhesives can be spray-applied in the same equipment currently used throughout the industry to yield formaldehyde-free fiberboards with reduced PMDI content.

Collaboration continues to scale PAG manufacturing to the multi-ton level to enable full production runs at commercial mills in 2021. The researchers report about 400 million tons of asphalt are applied each year in the U.S., so the market potential for the newly created soy polymer is significant.

Cochran says asphalt paving is only the first use of the polymer; the research team is looking at other applications like preservation treatments for pavements and shingles, compostable impact modifiers, coatings, and adhesives.

The ACS Cooperative Research Award in Polymer Science & Engineering was established in 1992 and is presented annually.