Effect of aging on chemical and rheological properties of SBS modified asphalt with different compositions

Abstract

The simultaneous polymer degradation and asphalt oxidation of polymer modified asphalt (PMA) binder make it difficult to understand the rheological behavior of PMA in the aging process. The present study was meant to investigate the rheological behavior of various PMAs before and after aging (Rolling Thin Film Oven Test (RTFOT) and Pressure Aging Vessel (PAV)) by using rheological master curves in combination with Gel Permeation Chromatography (GPC). The GPC test was performed to obtain the average molecular weight (Mw) of the polymer and distribution of asphaltenes and maltenes.The properties of chemical and rheological were analyzed comprehensively and the results indicated that the phase angle (δ) is more sensitive to asphalt composition (sulfur contents, polymer and base binder characteristic) than the complex shear modulus. Besides, the δ shape can strongly reflect the differences between the rheological responses of the modified asphalts under the different aging conditions. A plateau would occur if the SBS network was formed. Thus the δ shape of SBS modified asphalt will be closer to that of base binder when SBS structure was completely destroyed. Although the degradation of polymer became severer when sulfur was added, sulfur can promote the formation of three-dimensional structures of styrene–butadiene–styrene (SBS) and improve the rheological property of aged PMAs.