Research Highlights

Soy is paving the way for better roads

By Carol Brown, USB database communications

Sometimes a research project goes in a different direction than scientists expect. Researchers in North Dakota literally found that out the hard way.

A project that explored how well a soy-based agent reduced dust on gravel roads turned into something bigger. And it could mean wins for both the soybean and transportation industries.

“In the summer of 2017, we did a gravel road test using a soy-based material as a dust-control agent,” said Jim Bahr, lead project investigator. “After about six weeks, the gravel surface became firm and black and looked like a paved road.”

The road they had selected for the test had reclaimed asphalt pavement, or RAP, mixed in with the gravel, Bahr said. They had applied about 1,000 gallons of the soy-based dust control agent onto the gravel road, which interacted with the RAP to harden the surface after several weeks.

The researchers are pursuing the future of this unforeseen, positive side effect.

Re-use, recycle

Bahr said RAP is used often on gravel roads to stabilize the surface. He and his fellow researchers are tapping into the enormous stockpile of RAP to find new uses for it. In doing so, they’re also creating a new use for soybean oil.

Bahr is a senior research engineer at North Dakota State University (NDSU) Office for Research and Creative Activity. He partnered with Dr. Ying Huang, who studies asphalt in the NDSU civil engineering department. She manages the lab for testing asphalt properties.

In the lab, they’ve concocted mixtures of RAP with the soy dust control agent to create a new road material. It takes the right recipe of soy oil and recycled asphalt to be strong for traffic, but also pliable enough for surface application and to withstand hot and cold weather conditions. Bahr said traditional asphalt becomes hard and brittle as it ages. Blending the soy-based material with the old asphalt softens it up and allows the RAP to re-establish its binder properties.

New uses for soybeans

By using the soy-based dust control agent with the ground-up recycled pavement, a stable road surface could be possible — and a new use for soybean oil is created.

“This helps to expand the markets for soybeans in the United States,” said Kendall Nichols, research director for the North Dakota Soybean Council (NCSC), the major funder for this project. “This material has great potential for road dust control and RAP rejuvenation, both of which are large U.S. markets.”

If the soy-based material replaced just 10 percent of the road treatments for dust control and 5 percent of the yearly RAP generated in the country, it is estimated to use about 50 million soybean bushels annually, Nichols said. Creating new markets for soybeans within the United States helps to improve the grain’s value.

Next steps

The soy-based agent could be used for either road dust control or asphalt, making it a versatile product. Bahr’s next step is to road-test the rejuvenated asphalt material in North Dakota. He’s looking to get others involved including the state Department of Transportation, which has expressed interest.

“I’d like to test the asphalt on sections of roads,” Bahr said. “Maybe it will work as a road surface or maybe it will be better as an underlayment and have asphalt put on top of it.”

Bahr’s vision also goes beyond the state’s borders.

“I’d like to conduct dust control road tests throughout the upper Midwest,” he said. “Gravel is made with local materials, which varies with geology. I want to see how the soy-based agent interacts with the different gravels found across the Midwestern states.”

Using a soy-based product on both paved and gravel roads has great potential for the transportation industry as well as for agriculture. Someday, soybean farmers could enjoy the fruits of their labor on the roads they travel daily.

Published: Nov 25, 2019