NRRA: Novel Methods for Adding Rejuvenators in Asphalt Mixtures with High Recycled Binder Ratios

Status:  Complete
Report Date:  07/28/2022


Asphalt rejuvenators are used to incorporate higher amounts of Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt (HMA) without detrimentally impacting the long-term performance of the pavement. Rejuvenating agents (RAs) are relatively new in the HMA industry and there are many different products marketed to transportation agencies. However, most of these products have limited field and laboratory test data available to support their effectiveness over time. Several recent research efforts have shown that some products, while effective immediately after production, show rapid decrease in effectiveness with aging. Therefore, there is a need for a better understanding of how various RAs perform over time through both laboratory and field evaluations to help guide engineers on appropriate usage of these materials. The National Road Research Alliance (NRRA) Flexible Team constructed field test sections as part of a mill and overlay project on Trunk Highway 6 (TH6) located in Emily, MN in August of 2019. These field sections include wearing courses with 40% RAP that incorporate seven different RA products, with the dosage determined by the supplier to meet a target extracted and recovered performance grade (PG) of XX-34. In addition to the RA test sections, there are control sections with 40% RAP and 30% RAP (the maximum level allowed on remainder of this project). Mixtures and binders were sampled at the time of production and one set of field cores was taken shortly after construction. Mixture tests on the plant produced mixtures are being conducted by NRRA members and MnDOT will be monitoring the performance of the field sections over time. The objective of this research project is to evaluate the effectiveness of the seven RA products over time and evaluate their performance as compared to the control mixtures. This will be accomplished through a combination of binder and mixture characterization and performance testing using different laboratory aging levels, field core testing, and performance monitoring of the field sections over time.

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