Effect of aggregate selection and design gyrations on the performance of polymer and devulcanized rubber modified mixtures

The objective of this study was to investigate the potential performance improvement of asphalt mixtures by changing the source of aggregates and the number of design gyrations during the mix-design process. Two surface course mixtures were produced in the laboratory using common Michigan’s aggregates and polymer modified binders. Their linear viscoelastic behavior was evaluated in the laboratory, together with the resistance to rutting, fatigue, and thermal cracking. The same characterization was performed on two mixtures designed with aggregates of better quality, a higher level of compaction (i.e., design gyrations), and the same binder type. Results were used for a direct comparison of thermal cracking susceptibility and for calibrating the rutting and fatigue cracking models of the Mechanistic-Empirical Pavement Design Guide (MEPDG). Results showed that the resistance to all the major pavement distresses improved sensibly. Moreover, it was observed that the presence of aggregate of better quality together with the application of higher compaction level did not affect the binder quantity of the enhanced mixtures (± 0.2%) which could be a major economic concern for State Departments. The results of this research could lead to a revision of the Superpave mix-design criteria currently adopted by the Department of Transportation.