Relating asphalt binder elastic recovery properties to HMA cracking and fracture properties

Cracking in HMA pavements reduces the long-term durability of HMA pavements and undesirably increases the costs of road maintenance. Asphalt binder as one of major constituents of HMA plays an important role in the HMA cracking performance. Previous studies have indicated that higher elastic recovery of asphalt binder was favored to resist fatigue cracking. This study was undertaken to further investigate the relationships between the asphalt binder elastic recovery (ER) properties and the HMA cracking resistance and fracture properties, measured in the laboratory. The ER test (or ductility test) and MSCR test were used to measure and quantify the asphalt binder ER properties. Similarly, the OT and IDT tests were used to measure and quantify the HMA cracking resistance (cycles to crack failure) and fracture properties (tensile strength, fracture energy [FE], and FE Index), respectively. The test results indicated that HMA mixes with high ER properties (⩾59%) showed superior fracture properties and better laboratory cracking resistance performance, i.e., higher FE Index values (>1.0) and more load cycles to crack failure (>500 OT cycles), respectively. By contrast, no definitive performance trends were found for the HMA mixes with low ER properties (<59%).