Evaluation of Fatigue Tests for Characterizing Asphalt Binders

The current performance grade (PG) binder specification uses the parameter G* sin delta to quantify binder fatigue property, which has long been known to be the weakest part of the specification. The purpose of this study was to identify a better binder fatigue test. Six asphalt binders with a variety of modifiers were characterized using five asphalt binder tests, including the G* sin delta, elastic recovery test, the multiple stress creep recovery (MSCR) test, the linear amplitude sweep (LAS) test, and the double edge notch tension (DENT) test in this study. Additionally, the push-pull asphalt mix fatigue test was employed to verify these binder fatigue tests. Comparing the results of the binder tests and the asphalt mix push-pull test, this study further confirmed the poor performance of the parameter G* sin delta to differentiate binder fatigue resistance. It was also found that neither the MSCR nor the LAS test showed good correlation with asphalt mix fatigue resistance. Finally, it was identified that both the DENT and the elastic recovery binder fatigue tests provided the same ranking as the asphalt mix fatigue test. The DENT test is recommended for characterizing asphalt binder fatigue resistance, because it is more fundamentally based than the fully empirical elastic recovery test. Obviously, these findings are based on laboratory tests only, so further field validation is needed. Additionally, one needs always to keep in mind that the binder alone does not determine fatigue life of a pavement structure, and other factors such as traffic and environment are also important. DOI: 10.1061/(ASCE)MT.1943-5533.0000625. (C) 2013 American Society of Civil Engineers.