Iowa State University's Soy-Based Asphalt Technology Achieves Major Milestone on State Roadways

During the transition from late summer to early autumn in 2025, a significant infrastructure milestone was reached in northeastern Iowa. Engineers from Iowa State University (ISU) successfully completed a large-scale demonstration of innovative soy-based road materials. This initiative, brought to market by SoyLei Innovative Products, spanned approximately 25 linear miles of roadway across Fayette and Clayton counties, including the city of Volga. The project represents a major advancement in the modernization and strengthening of rural infrastructure within the region.

The core of this technological breakthrough lies in the creation of base layers utilizing 100% recycled asphalt pavement through a cold-in-place process. Central to this achievement is the SIP-1111 rejuvenator, a specialized product composed of 95% soybean oil. This bio-based formulation works by chemically restoring the elasticity of aged, oxidized asphalt binders. By revitalizing the old material, the technology empowers contractors to incorporate significantly higher proportions of recycled asphalt pavement (RAP). In the specific cases of Clayton and Fayette counties, this rejuvenator was instrumental in establishing a base made entirely of recycled materials via an innovative asphalt foaming technique.

Dr. Eric Cochran, an Iowa State University professor and the scientific founder of SoyLei, explained that the process effectively integrates soy into the very fabric of the road by replacing petroleum-derived asphalt modifiers with soybean oil polymers. The 2025 application scale signaled a definitive shift from experimental pilot testing to practical, large-scale implementation, utilizing roughly 11,000 bushels of soybeans. The economic benefits were immediately apparent, as Fayette County reported savings of approximately $97,000 in costs related to foamed binder alone. Furthermore, ISU engineers estimated that the project successfully avoided the consumption of more than 40,000 barrels of crude oil by drastically reducing the need for new petroleum products.

This technological advancement is the result of years of dedicated research at Iowa State University, with commercialization efforts led by SoyLei Innovative Products since its founding in 2020. Dr. R. Christopher Williams, a professor of civil engineering at ISU, stands alongside Dr. Cochran as a pivotal figure in the development of these materials. Their flagship product, SIP-1111, is notable for being entirely free of volatile organic compounds (VOC-free). This environmentally conscious solution allows for the inclusion of up to 50% RAP in asphalt surface layers, providing a cost-effective and sustainable alternative to traditional, petroleum-heavy rejuvenators.

Looking forward from February 2026, the success of the base layer application has sparked significant interest in expanding the use of soy-based products. Future projects are expected to target high-RAP content in hot-mix asphalt as well as various surface conservation efforts. The successful transition from laboratory research—which received vital support from the Iowa Soybean Association and the Soybean Council—to the physical construction of 25 miles of roadway confirms the long-term viability of soy-based technology in the future of road construction.