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Paving the way with soy

A biopolymer using high-oleic soybean oil could soon be replacing petroleum-based products in asphalt.

Lynn Betts

November 27, 2019

9 Slides

Iowa State University research engineers have good news for soybean growers: a soy oil polymer for asphalt paving.

After nine years of development, the ISU research team is closing in on commercializing a high-oleic soy oil polymer that can replace petroleum-based polymers in asphalt paving. The bio-based binding agent is an economical, efficient and sustainable option for asphalt pavers with the potential to open a new — and  large — market for soybean growers.

High-oleic soy oil produces a polymer that’s very elastic, like a rubber band, research team leaders Christopher Williams and Eric Cochran told an audience at a paving demonstration near Ames in mid-November.

“It’s less likely to crack in cold climates, and that’s a real performance advantage over petroleum-based polymers,” Williams said. “We expect asphalt using this polymer binding to last well over 20 years. It’s been tested by transportation departments in 30 states with more than 4 million truck loadings, and we’re confident it’s high quality. Along with that, this technology could save $3,000 per lane mile of paving. That’s a very conservative estimate.”

Seeing is believing

A parking lot was paved with asphalt containing soy oil polymer to demonstrate its elasticity and how easily it handles. The biopolymer allowed nearly 25% recycled asphalt pavement to be used in the project without performance trade-offs, leading to major cost savings. The lot is just a few steps from the pilot polymer plant built in 2015 at the ISU BioCentury Research Farm that was used to perfect the process of producing a polymer that’s not too thick or too thin, and to ramp up the process for commercial production and de-risk the use of the product.

Bill Rosener, executive vice president of the Asphalt Paving Association of Iowa, says asphalt is 95% aggregate and 5% asphalt cement, which glues the rock and sand together. “The new biopolymer is a substantial alternative to using highly volatile and expensive chemicals that have been used in the past to create the polymers in the cement,” he said.

“We know we have a high-quality product, but people need to see it to believe it,” Cochran said. Demonstrations have already been conducted in Brainerd, Minn., and Grimes, Iowa. On deck are demos in Alabama and Texas this winter and then next spring in South Dakota, Nebraska, Indiana and Missouri.

Enormous potential

About 300 million tons of asphalt are applied each year in the U.S., so the market potential for soy polymer is significant.

Rolland Schnell has been involved with the soy oil polymer project for nine years. The soybean producer from Newton in central Iowa was on the Iowa Soybean Association board at the time ISA approved funding for the project. “I’ve been waiting for this day for a long time,” Schnell said. “My philosophy is to look at the big picture, down the road, and my goal has been to see high oleic as the commodity soybean. It’s use for asphalt paving fits in; there’s a potential for selling a large volume of high-oleic soy oil for this.”

“We get pretty excited about what our beans can do and where they end up particularly when it fills a market need and brings profit opportunities to farmers across the country,” said Gregg Fujan, a Nebraska farmer who serves on the United Soybean Board. “We see this use of soy oil as one more piece of the puzzle to increasing the demand for soybeans. Export markets are important, but if we can use more products domestically, we can have a more consistent market and don’t have to worry so much about the political issues involved in export markets. This is a big step forward.” Fujan is looking forward to having an asphalt paving demonstration in Nebraska.

High on high-oleic beans

“Tested time and again, high-oleic soybean oil outperforms other natural oils,” Fujan said. “It’s an economical and sustainable choice for all sorts of products and applications in everything from paints to plastics to turf, including asphalt. But the market has to be there before farmers will grow high-oleic beans. We hope to find yet another satisfied customer in asphalt pavers as we bring another soy product to the market.”

Fujan knows firsthand that some of the profit reaped by end-users of high-oleic soy oil are passed along to the farmer. “High-oleic soybeans bring an average 50-cent premium on the bushel. I grew high-oleic beans on 250 acres and got a 45-cent premium,” Fujan said. “I’ll grow more next year if contracts are offered again.”

High-oleic soybeans are now grown in 13 states throughout the U.S. soybean belt. The acreage had grown to about 650,000 acres in 2017, after being launched commercially in 2012. The soybean industry’s goal for high-oleic soybeans is 16 million planted acres.

“It’s our mission to innovate beyond the bushel and add value to U.S. soy,” Fujan said. “USB’s farmer-leaders and staff work hard every day to provide opportunities like this one through building strategic partnerships, funding innovative research and anything and everything else you can think of that drives demand and preference for U.S. soybeans.”

The paving project has been a collaborative effort by the ISU research team, United Soybean Board, Iowa Soybean Association, Asphalt Paving Association and other partners. Industrial, non-biodiesel uses made up more than 7% of the domestic demand for U.S. soybean oil in the 2016-17 marketing year; use in asphalt paving may well increase that percentage in a few years.

Schnell says soy oil polymers bring a new advantage to himself and other growers. “This polymer could be used in our state, across the country, and who knows, maybe across the world. It’s a perfect example of using soybean checkoff funds to add value to our soybean products. Soybeans not only help feed and fuel the world, but now we can help pave it, too.”

Betts writes from Johnston, Iowa.


Scaling up polymer production

After seeing a nationwide shortage in SBS, the primary polymer for asphalt, Seneca Petroleum began working with ISU researchers to develop a biopolymer alternative. Argo Genesis Chemical LLC, a sister company to Seneca, built a $5.3 million Bio-Polymer Processing Facility in 2015 at the ISU BioCentury Research Farm and turned it over to ISU to ramp up biopolymer production.

ISU engineers Christopher Williams and Eric Cochran led the way in researching and developing the chemical process to convert soybean oil into thermoplastics. A $250,000 investment from the Iowa Soybean Association and the United Soybean Board was leveraged to $13 million from private, state and federal funds to scale up the processes and turn the highly elastic polymers into commercial products. Cochran says asphalt paving is only the first use of the polymer; the research team is looking at other applications.

Watch the video of the recent paving demonstration at the ISU BioCentury Research Farm using the new high-oleic soy oil product as a binder for asphalt.


About the Author(s)

Lynn Betts

Lynn Betts writes from Johnston, Iowa. He is a frequent contributor to Wallaces Farmer.

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