Performance-graded asphalt binder selection catalog for asphalt overlays

The selection of a proper asphalt binder grade is an important step toward a long-lasting asphalt pavement. Currently, almost all states in the US are grading asphalt binders using the Performance-Graded (PG) system, which was originally developed for new pavement constructions three decades ago. Nowadays, asphalt overlays rather than new pavement constructions are the predominant work most state Departments of Transportation (DOTs) deal with. The biggest difference between new pavement constructions and asphalt overlays is preexisting cracks underlying the asphalt overlays, which are not considered in current PG asphalt binder selection catalogs used by many DOTs. Therefore, it is critical to address this practical need for a new PG binder selection catalog suitable for asphalt overlays. This paper employed a calibrated mechanistic-empirical asphalt concrete overlay program (TxACOL) to simulate the reflective cracking performance of 2700 asphalt overlay cases under five climatic conditions, four traffic levels, three overlay thicknesses, three existing pavement types, and fifteen aggregate/binder combinations. Based on the reflective cracking simulation results, two new colorcoded binder grade maps were developed - one for asphalt overlays over existing asphalt pavement and another for asphalt overlays over existing jointed plain concrete pavements. Furthermore, a life cycle cost analysis was conducted to confirm the validity of the new binder selection catalog for asphalt overlays. Finally, a revised binder selection catalog was recommended for TxDOT to incorporate asphalt overlays as part of the binder selection process.