Past Research Cycle Highlights
Seventh Cycle of Accelerated Performance Testing
The seventh cycle of accelerated performance testing began in 2018, providing unique opportunities to determine the field performance of breakthrough materials and concepts without the risk of failure that local and state agencies are unwilling to accept. Research during this cycle primarily focuses on pavement preservation, balanced mix design, cracking tests, and rejuvenators.
Pavement Preservation
The pavement preservation group study is quantifying the life-extending and condition-improving benefits of different pavement preservation treatments on both low-volume and high-volume roadways across northern and southern climates.
By determining the field performance of treatments applied at various pavement life stages, agencies will gain data-driven insights for selecting preservation treatments. A secondary focus of the study is developing specifications and quality assurance guidelines for pavement preservation.
Find out more about our pavement preservation study here.
Many of the same treatments used in Alabama are also being tested in Minnesota using MnDOT materials and methods. The northern pavement preservation experiment includes sections on U.S. Route 169 (high-volume) and County State Aid Highway 8 (low-volume). Learn more about this study.
Balanced Mix Design
Four test sections on the Test Track focus on balanced mix design, sponsored by the Oklahoma and Texas Departments of Transportation. Oklahoma’s approach uses the Hamburg wheel tracking test for rutting resistance and the Illinois flexibility index for cracking resistance.
Texas’ balanced mix design specification requires the Hamburg wheel tracking test for rutting resistance and the overlay test for cracking resistance. Their goal is to compare the performance of balanced mix design asphalt mixes against those designed using the Superpave volumetric approach under accelerated loading.
Cracking Group
The cracking group experiment aims to develop and implement performance tests that predict pavement cracking across various distress types found in North America. While several lab tests claim to assess cracking, most lack validation beyond the state where they were developed.
Both MnROAD and NCAT have established test sections to validate laboratory cracking tests by correlating results with real-world performance. This research helps establish specification criteria for cracking susceptibility.
Regular performance monitoring includes assessments of ride quality, distresses, pavement strength, and response. Read more about the MnROAD study here.
Rejuvenators
Cargill is sponsoring research at both the NCAT Test Track and MnROAD to evaluate balanced mix design procedures in asphalt mixes containing rejuvenators and high levels of reclaimed asphalt pavement.
Test sections made with Cargill’s Anova rejuvenator and a 45% reclaimed asphalt mix will be compared to control sections with lower recycled content. Researchers will assess factors such as pavement ride quality, cracking, and rutting under different climate conditions.
Mississippi and Tennessee DOTs have also sponsored rejuvenating seal experiments. NCAT conducted preliminary screening of seven rejuvenating seals, ranking them based on rheological properties and friction test results.
The Mississippi DOT selected ReGenX™ (Blacklidge Emulsions) and Delta Mist™ (Collaborative Aggregates LLC) for evaluation on its S3 Test Track section. The Tennessee DOT selected Reclamite® (Ergon) and e-Fog S (Ergon) for its S4 section. These four rejuvenating fog seals will be evaluated over the two-year Test Track cycle.
More details about the preliminary study can be found here.
Additionally, Section N7 with Delta S®, sponsored by Collaborative Aggregates LLC, continues to be monitored following completion of the 2015-2017 research cycle.