Case Study: NCAT Test Track

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Situation

The road construction industry has historically lacked long-term performance studies on rejuvenated high reclaimed asphalt pavement (RAP) mixtures. Without comprehensive field data, agencies and contractors have had limited information to evaluate the long-term performance and value of rejuvenators in asphalt pavement.

To help address this gap, Cargill funded a long-term research program with the National Center for Asphalt Technology (NCAT) at Auburn University in collaboration with the Virginia Department of Transportation (VDOT). After more than 20 million equivalent single axle loads (ESALs)—representing over six years of accelerated traffic loading and field monitoring—the program has generated one of the industry's most comprehensive datasets demonstrating the long-term reliability and consistency of high-RAP pavements using Anova® biobased rejuvenator.

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Goal

The objective of this multi-year research program was to answer critical questions surrounding how performance-based specifications can help agencies confidently specify rejuvenated high-RAP asphalt mixtures while demonstrating the long-term viability, durability and performance of pavements produced with Anova® Rejuvenator.

Now scheduled to span a full nine years, the NCAT study is positioned to serve as a national benchmark for evaluating the long-term performance of rejuvenated asphalt mixtures. Findings are shared openly with transportation agencies and industry partners to support informed decisions around alternative pavement designs and performance-based specifications.

In parallel, Cargill has completed more than seven years of evaluating rejuvenated asphalt mixtures at the Minnesota Department of Transportation's MnROAD test facility, providing additional validation in cold-weather conditions.

Solution

The research team developed a comprehensive field and laboratory evaluation comparing a 45% RAP mixture containing Anova® Rejuvenator with a conventional 30% RAP control mixture (9.5 mm NMAS VDOT Balanced Mix Design).

Plant-produced mixtures from the NCAT Test Track were evaluated through extensive laboratory testing, including:

  • Cracking resistance
  • Rutting performance
  • Moisture resistance
  • Binder performance
  • Field aging characteristics

The accelerated loading provided by the NCAT Test Track allowed researchers to simulate more than a decade of interstate traffic in just a few years, providing valuable long-term performance data under real environmental conditions.

According to Dr. Buzz Powell, former Associate Director and Research Professor at NCAT:

“Hats off to Cargill for funding such important research with results shared with 34 state agencies in the country,” said Powell. “This work adds so much credibility to the use of RAP and helps the entire industry move forward with proven technologies that brings greater value to our communities and road construction businesses as a whole.”

Results

After more than seven years of testing and approximately 20 million ESALs, the Anova® Rejuvenator section continues to demonstrate outstanding long-term performance.

Key findings include:
  • Minimal cracking after more than seven years of service
  • No rutting damage observed
  • Ride quality (IRI) remained excellent and comparable to—or better than—the control section
    • Laboratory testing confirmed strong rutting and cracking resistance, including:
    • APA rutting performance of approximately 2.55 mm
    • IDEAL-CT cracking index of 100
    • Disk-Shaped Compact Tension (DCT) fracture energy of approximately 565 J/m²
  • Increasing RAP from 30% to 45% reduced the mix's global warming potential by approximately 10–15%
  • Contractors can realize $0.50–$1.50 per ton in material savings, equating to roughly $750,000 annually for a midsized producer through reduced virgin asphalt binder and aggregate usage.
  • Improved workability and compaction help contractors consistently achieve target densities and potential quality incentives.

As Nam Tran, Assistant Director and Research Professor at NCAT, noted:

“These results are going to be very impactful for the industry,” said Nam Tram, Assistant Director and Research Professor at NCAT. “These multi-generational results show that transitioning from standard volumetric to balance mix design asphalt should be considered as a consistent solution to meet industry performance, cost and environmental goals.”

Table 1 Divider transparent NCAT Test Track Graphs

 

Key Learning

The NCAT program, together with Cargill's long-term evaluation at MnROAD, has become one of the industry's longest-running and most comprehensive studies of rejuvenated high-RAP asphalt mixtures.

More than seven years of field performance demonstrate that pavements produced with Anova® Rejuvenator continue to deliver exceptional durability with little evidence of age-related distress. Researchers also observed excellent surface condition, with no significant changes in texture or raveling, confirming the long-term stability of the rejuvenated binder.

In addition, field core analysis showed that the rejuvenated binder experienced only minimal changes in low-temperature performance grade over time, indicating superior aging stability compared with the control mixture. Together, these findings provide transportation agencies, contractors and pavement owners with long-term, independent evidence that rejuvenated high-RAP mixtures can successfully achieve performance, sustainability and cost objectives while supporting broader adoption of performance-based pavement specifications.