RHEOLOGICAL AND THERMAL BEHAVIOR OF WEATHERING-AGED POLYMER MODIFIED BITUMEN

Abstract

This paper evaluates the effect of weathering degradation on styrene-butadiene-styrene modified bitumen and conventional bitumen using a dynamic shear rheometer and thermal analysis. The aging was done in two steps: samples of asphalt binder were aged for a short term in the rolling thin film oven for 85 minutes. The long term aging was done in a weathering chamber at the determined temperature with UV rays acting on the thin film surface of binder (after RTFOT aging) covering rock plates for different exposure times. At low frequencies, the complex modulus of asphalt binders with and without polymer additions increased as the exposure time in the weathering chamber increased. Before aging, the complex modulus of polymer modified bitumen was higher than the complex modulus of conventional asphalt binder at low frequencies. For 50h aging, SBS modified bitumen showed a lower complex modulus at low frequencies than the conventional bitumen. For 100h aging, the benefit of polymer addition was minimized, and values of complex modulus of both binders were close. Thermal analysis showed a marked drop in thermal stability of aged samples after 100 hours for the polymer modified bitumen and after 50 hours for the conventional bitumen. KEYWORDS