Use of Anova Asphalt Rejuvenator and Balanced Mix Design Principle to Improve the Performance of High-RAP Asphalt Mixtures
Type of DegreeMaster's Thesis
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The use of recycled materials like Reclaimed Asphalt Pavement (RAP) in asphalt mixtures is now a common practice with associated economic, social, and environmental benefits. However, asphalt mixture performance issues, especially cracking resistance, is a source of concern when the RAP content in the asphalt mixture is high. To address this challenge, utilization of recycling agents, also known as rejuvenators, can potentially restore the properties of the aged asphalt binders and improve the overall cracking resistance of the asphalt mixture. To that effect, this project was conducted to evaluate the laboratory and field performance of a high-RAP asphalt mixture, which contains Anova asphalt rejuvenator and was designed by following the Virginia Departments of Transportation (VDOT) provisional Balanced Mix Design (BMD) specifications. To evaluate and compare the laboratory performance of rejuvenated and non-rejuvenated RAP mixtures, three plant-produced asphalt mixtures, including the control and two experimental asphalt mixtures, were considered. The control asphalt mixture has 30% RAP with no rejuvenator, the first experimental asphalt mixture has 45% RAP with Anova asphalt rejuvenator, and the second experimental asphalt mixture has 45% RAP but no rejuvenator. As a comparison with the laboratory performance of the plant-produced mixes, the control asphalt mixture and the first experimental asphalt mixtures were produced and placed in the surface layer of two 100-foot Sections N3A and N3B, which were divided from a 200-foot Section N3 at the National Center for Asphalt Technology (NCAT) Pavement Test Track. The results of the laboratory rutting tests of the control asphalt mixture and the first experimental asphalt mixture showed that the rutting resistance of both asphalt mixtures is not statistically different. Concerning cracking resistance, cracking test results of the Illinois Flexibility Index Test (I-FIT), Overlay Test (OT), and Disc-Shaped Compact Tension (DCT) test suggested that the first experimental asphalt mixture outperformed both the control asphalt mixture and the second experimental asphalt mixture. However, the indirect tensile asphalt cracking test (IDEAL-CT) results suggested that the control asphalt mixture had the best cracking resistance. At the NCAT Pavement Test Track, the early field performance of Sections N3A and N3B, with approximately 2 million Equivalent Single Axle Loads (ESALs) of traffic applied, indicates no visible cracking and low rutting of the surface asphalt mixtures. The current average International Roughness Index (IRI) values of N3A and N3B, by VDOT standard, classify the ride quality of both Sections as “good.” In summary, the laboratory test results and the early field performance of Sections N3A and N3B have shown that the use of Anova asphalt rejuvenator in the 45% RAP asphalt mixtures performs the same or in some instances, better than the control 30% RAP asphalt mixture without rejuvenator, with the exception of the IDEAL – CT result. Both asphalt mixtures were designed by following the VDOT’s BMD provisional specifications.