Effect of long-term laboratory aging on rheological properties and cracking resistance of polymer-modified asphalt binders at intermediate and low temperature range

Abstract Aging of modified asphalt binder has a great influence on its rheological property and paving performance, and decreases the quality of asphalt pavements. The primary objectives of this study were to investigate the effect of long-term laboratory aging on rheological properties and cracking resistance of polymer-modified asphalt binders at intermediate and low temperature range, and to analyze different evaluation indexes. SBS modified asphalt and two kinds of SBS/crumb rubber compound modified asphalt were subjected to Rolling Thin Film Oven (RTFO) test and 20 h, 40 h, 60 h Pressure Aging Vessel (PAV) test. Two rheological methods (frequency sweep test and Bending Beam Rheometer test) and a conventional test (Fraass breaking point test) were applied. Experimental results indicate that the studied binders tend to be more viscous at relatively low loading frequencies and harder after aging, and the ability to relax internal stress declines. Master curves and aging sensitivity analysis show that after 40 h PAV test, the effect of aging on polymer-modified asphalt binders rheological properties and cracking resistance becomes insignificant. The phase angle master curve can well reflect the effect of aging on asphalt binders rheological properties since the shape of phase angle master curve is obviously different before and after aging. Besides, critical temperature from BBR and Fraass breaking point tests can only be regarded as a reference of the minimum service temperature of asphalt pavements, and it can hardly reflect the impact of aging on materials property. While Glover-Rowe (G-R) parameter and ΔTc are well-related to asphalt binders rheological and physical properties when used to evaluate the age-related cracking resistance of asphalt binders. Besides, SR2 compound modified asphalt binder exhibits a better cracking resistance compared with the other two binders. Its G-R values range from 5.09 to 19.24 kPa among the whole aging conditions, besides, both of the minimum critical and Fraass breaking temperatures are under –23.41 °C.