Cargill and The Shelly Company Collaborate on Bio-Binder-Based Mix that's Shifting City Paving Specifications

As a leader in renewable asphalt solutions, Cargill continues to push the industry forward with new technologies that improve on the past. To make this happen, however, the global manufacturer of plant-based asphalt technologies and additives, continues to collaborate with industry partners who share the vision of creating more sustainable paving technologies.

The Shelly Company (a CRH business), based on Thornville, Ohio, has been a long-term industry partner with Cargill. The organizations have been working on an innovative solution using Cargill's new bio-binder in a high RAP (recycled asphalt pavement) mix that reduces the carbon input typically associated with repaving projects. 

Through its work in the region, The Shelly Company was aware of a repaving project in city of Aurora, Ohio, a community located between Cleveland and Akron, that could be a forward-thinking partner to initiate this groundbreaking project.

Although this was the first trial of its kind in North America, city officials were open to the idea of finding a more sustainable solution when paving a nearly one mile long, two-land residential street requiring 1,000 tons of mix.

"Even though we typically require virgin asphalt in our paving specs, we're always looking for more innovative ways to address the needs of our city," said Harry Stark, Director of Public Services with the City of Aurora, Ohio. "So, when the Shelly Company approached us with this option, we were excited to give it a try as we strive to meet our long-term environmental, financial and quality control objectives."

Solution

Based on the lab tests and trust the city had with The Shelly Company and Cargill, a shift was made to Aurora's long-standing specification of using virgin asphalt to run with this alternative mix comprised of high RAP, warm mix additive and the plant-based binder. 

With the go-ahead from the city in June 2023, Cargill and The Shelly Company perfected the right mix formula that ultimately replaced a significant amount of petroleum-based liquid asphalt with a high-performance low carbon bio-binder.

The binder was incorporated in a 64-22 grade mix that normally includes Cargill's proven Anova rejuvenator, with 40% RAP. This combination drops the amount of virgin bitumen used to 4%, significantly boosting the use of renewable materials across all 1,000 tons of recycled asphalt for the project. 

"We're always trying to find new innovation solutions for our city's needs, yet it's hard to change set ways of doing things," added Stark. "But after learning more about the work The Shelly Company and Cargill have been doing on these bio-based alternatives in other parts of the world, we felt confident that changing our specs for this new technology was the right move to make."

Key Results

Following a series of lab tests before and after production, the bio-binder with high RAP mix showed that such mixes can be produced without compromising on quality, durability, ease of use and appearance. 

Overall, the contractor calculated a 31% reduction in their carbon footprint while achieving 94% paving density with no cracking or rutting based on standardized testing such as the Pike Hamburg method, showing strong potential for use around the world as more cities and countries seek new ways to reduce dependence on carbon-based materials.

"For us, after using mainly virgin mix until now, we realize there's great opportunity for more cities to adopt this technology for more road construction applications," said Stark. "If there's a way to be more environmentally friendly and still product a good product, the benefits seem to speak for themselves."

And although the mix was brand new for the paving contractor, Akron, Ohio-based Perrin Asphalt, reported that they didn't need to make any adjustments to their standard paving process.

The Cargill-Shelly mix functioned like any other conventional virgin mix and didn't require any vibratory rolling, still achieving 94% density. The workability of the mix allowed Perrin to stay on schedule and ended up with the same, if not better result, given the environmental benefits.

"Our mission is to reinvent the way the world is built," said Chad Reel, Vice President, and General Manager of The Shelly Company's Northeast Division. "The world is changing so how can we be a more proactive leader in our industry to come up with the solutions that help mitigate our carbon footprint, be more environmentally sound, and put out a quality product. This project was a great opportunity to do just that."

Given the positive results of the trial and the ongoing partnership with CRH, Cargill is continuing to refine the binder with the hopes to roll this out globally in the near future, allowing more public entities to reduce their overall carbon use and providing more sustainable solutions for transportation infrastructures.

More Asphalt Solutions