U.S. Soy ℠ is replacing petroleum in American infrastructure

Last summer, a train of heavy equipment crawled along 8.6 miles of County Road C14 in northeast Iowa. One machine stripped off the top four inches of a road first built in the 1960s. The next ground up that old pavement and blended it with a fresh binder. A paver laid the recycled mix back down, and a pair of rollers pressed it smooth. The road that came out was rebuilt almost entirely from itself, and the ingredient that made the recycling work was soybean oil. 

That stretch of County Road C14 was one piece of a 24-mile demonstration across Fayette and Clayton counties and the town of Volga, the largest field trial yet of what Iowa State University (ISU) researchers call soy asphalt. Soybean oil replaced the petroleum in the recycling emulsion, in the hot-mix asphalt and in the rejuvenator sprayed across the finished surface. The county engineers who oversaw the work reported clean, even pavement and a surface that drained and dried quickly through the first season. 

County Road C14 is an example of a shift underway across the country. For decades, the story of soybean oil has been told in the kitchen and the fuel tank. About 45 percent of U.S. soybean oil goes into food and roughly half into fuel, leaving industrial uses as the smallest share.1 That share is where some of the most interesting growth is happening, and increasingly it runs right under the tires of every American driver. Soybean oil is now an active ingredient in the materials that build and maintain roads, rejuvenating aging asphalt, protecting concrete from the inside out, and brightening the lines that keep traffic in its lane. In each case, soy is displacing a petroleum-based product, and in each case the performance argument is built on science. 

“High-oleic soybean oil is proving to be an important replacement for petroleum, not just in recycled asphalt but in many other industrial uses,” says Robb Ewoldt, a farmer leader from Iowa. “It’s grown right here in the Midwest, and as a renewable resource, it’s outperforming the petroleum products it replaces. That’s a win for soybean farmers and for every driver on the road.” 

Bringing old asphalt back to life
Asphalt hardens and cracks as it ages because oxygen breaks down its binder. At the molecular level, oxidation causes compounds called asphaltenes to clump together, which leaves the pavement stiff and brittle. A soy-based rejuvenator goes after that problem directly. The fatty acids in soybean oil penetrate the aged binder and break up the asphaltene clusters, restoring the balance the binder had when it was new. 

Researchers at ISU developed the technology with support from the Soy Checkoff, including the United Soybean Board and the Iowa Soybean Association. Lab work showed the soy rejuvenator could reduce the size of asphaltene particles by about 30 percent.2 The bigger payoff for road crews is recycling. Because the soy additive restores aged binder, contractors can pack far more reclaimed asphalt pavement into a new mix, which is exactly what the Iowa demonstration put on display. Crews recycled the existing road in place rather than hauling it off and trucking in all-new material. An earlier Indiana project pushed recycled content to 40 percent, well above the 20 to 25 percent that is typical, without giving up performance. 

“Asphalt hardens over time because those asphaltene molecules build up and stiffen the binder. Our chemistry goes after that hardening effect directly, and that’s what lets crews recycle so much of the old pavement instead of hauling it off and trucking in new material,” said Christopher Williams, professor of civil, construction and environmental engineering at ISU. 

Protecting concrete from within
Salt is hard on concrete. Every winter, road crews spread chloride deicers that soak into bridge decks and pavement joints, where they corrode reinforcing steel and trigger reactions that crack the concrete from the inside. Most products fight this by laying a thin film on the surface, and that film tends to wear away in two to three years. 

PoreShield™ takes a different approach. Made from soybeans as a soy methyl ester, it soaks deep into the pore network of the concrete and stays there as a fluid, water-repellent barrier. Because it works from within rather than on top, it keeps blocking moisture and chloride long after a surface treatment would have failed. PoreShield was developed at Purdue University in partnership with the Indiana Department of Transportation, the Indiana Soybean Alliance, USB and it is now sold by Crafco.3 

“Crafco is a large company with a global footprint that uses locally sourced products whenever possible,” Barry Alexander, USB director from Kentucky, says. “They’re a great fit for U.S. Soy.  It’s also a good way for the public to see that farmers produce more than food – we produce solutions.” 

The independent results are notable. A study sponsored by the Wisconsin Department of Transportation found PoreShield extended the service life of concrete pavement joints by 5.4 to 9 times compared with untreated concrete, and a Drexel University study found it cut the formation of a damaging salt compound, calcium oxychloride, by more than 90 percent.4 State transportation departments from Indiana and Iowa to Texas, Oregon and Nebraska have put it on real roads and bridges. 

Brighter lines, lower emissions
The painted lines on a highway take a beating from tires, weather and sun, and they have to dry quickly so traffic can keep moving. Conventional marking paint leans on petroleum solvents that evaporate into the air as it cures. A soy-based alternative replaces much of that petroleum with a binder made from soybean oil. 

BioStripe®, made by Aexcel Corporation, was the first soy alkyd traffic paint and uses the oil from more than 420 pounds of soybeans in every 100 gallons.5 It carries lower volatile organic compounds, applies with the same equipment crews already own, and its makers report it dries harder and resists dirt better than solvent-based paint, which keeps lines visible longer between repaintings. 

What it adds up to
Consider what one project required. The 24-mile Iowa demonstration put an estimated 12,000 to 15,000 bushels of soybeans into the ground and, by its engineers’ accounting, displaced roughly 40,000 barrels of crude oil.6 Now set that against the size of the whole system. The United States has more than 2.7 million miles of paved road, and about 94 percent of that surface is asphalt.7 Every one of those miles is maintained on a cycle, repaved, resealed and restriped year after year. Industrial uses account for only about 5 percent of soybean oil demand today, which leaves real room to grow as more of that maintenance work shifts to soy. 

That is the kind of demand farmers can count on. It does not hinge on a single export market or a single buyer, and it builds steadily as states and contractors adopt products that perform. Every gallon of soy rejuvenator, every bridge deck treated with a soy protectant, and every mile of soy-based striping turns bushels into a market that did not exist a decade ago. 

“Soybean farmers have been incredibly supportive and patient with us as we worked through the challenge of taking this from a laboratory concept to something you can actually walk on. The Soy Checkoff ℠, down to the state associations, is what made that possible,” said Eric Cochran, professor of chemical and biological engineering at ISU. 

This is farmer-funded research finding its way into the highways Americans drive on every day. The checkoff backed the early science, and now soy is doing the work, rebuilding rural roads from the pavement beneath them, quietly replacing petroleum one mile at a time. 

1 Editor’s note: the roughly-half-into-fuel figure is supported by Clean Fuels Alliance America, which states fuel now takes half of all domestically processed soybean oil. 

2 High-level neutron testing at Iowa State confirmed the 30 percent reduction in asphaltene particle diameter. Roads & Bridges, “Soybean oil-derived rejuvenator creates chemical reactions to restabilize RAP’s original SARA matrix,” 2021. https://www.roadsbridges.com/asphalt/article/10653684/soybean-oil-derived-rejuvenator-creates-chemical-reactions-to-restabilize-raps-original-sara-matrix 

3 PoreShield origin and current ownership. Purdue University Newsroom, “Arizona company acquires patented, soy-based concrete protectant developed in Indiana,” 2023. https://www.purdue.edu/newsroom/2023/Q4/arizona-company-acquires-patented-soy-based-concrete-protectant-developed-in-indiana/ 

4 Wisconsin DOT-sponsored study (Xiao et al., 2020) on PCCP joint service life, and Drexel University study (He et al., 2022) on calcium oxychloride reduction. PoreShield case study, “PoreShield for PCCP Joints.” https://poreshield.com/casestudies/poreshield-sme-ps-for-pccp-joints/ 

5 BioStripe soybean oil content and product claims. Aexcel Corporation, BioStripe product page. https://www.aexcelcorp.com/products/eco-friendly-traffic-paint/biostripe-sustainable-marking-paint-aexcel 

6 Project scope, bushel and crude-oil-displacement estimates for the Fayette/Clayton/Volga demonstration. Iowa State University News Service, “Soy-based pavement technology replaces, renews 24 miles of rural Iowa roadways,” 2026. https://www.news.iastate.edu/news/soy-based-pavement-technology-replaces-renews-24-miles-rural-iowa-roadways 

7 Paved road mileage and asphalt share. National Asphalt Pavement Association, citing Federal Highway Administration Highway Statistics data. https://www.asphaltpavement.org/expertise/engineering