Evaluation of aging behaviors of asphalt binders through different rheological indices

The performance of asphalt pavement is seriously affected by aging of asphalt binder, so indices are expected which can not only evaluate aging resistance of asphalt binder but also indicate asphalt mixture performance. The objective of this paper was just to investigate effects of different rheological indices which present tighter and clearer correlation with asphalt mixture performance in evaluating asphalt binder aging behaviors, these indices including complex modulus (G*) and phase angle (delta) master curves, rutting factor (G*/sin delta), zero shear viscosity (ZSV), non-recoverable compliance (J(nr)), fatigue factor (G*.sin delta) and DSR function (DSRFn). Thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) irradiation were applied to simulate short-term, long-term thermal oxidation and photo oxidation aging, respectively. Frequency sweep tests and multiple stress creep recovery (MSCR) tests were conducted on three asphalt binders (60/80 pen grade base asphalt, styrene-butadiene-styrenecopolymer (SBS) modified asphalt and styrene butadiene rubber (SBR) modified asphalt) at different aging conditions. Meanwhile, aging sensitivities shown by different rheological indices were compared. The relationships between rheological indices were also discussed. The results showed that the ranking of aging resistances among asphalt binders evaluated by different rheological indices were nearly consistent and SBS modified asphalt exhibited the best aging resistance to three aging methods. J(nr) and d tended to decrease with the growth of aging severity, whereas other rheological indices were just contrary to this trend. Moreover, DSRFn proved to be the most sensitive index to aging. Based on correlation analyses, three groups of indices exhibited a strong correlation to each other, namely DSRFn versus G*/sin delta, J(nr) (0.1 kPa) versus J(nr) (3.2 kPa) and J(nr) (0.1 kPa) versus ZSV.