Effect of blending protocol on the performance of SBS/sulfur/soybean-derived additive composite modified hard asphalt

This paper explores the feasibility of using SBS/sulfur/soybean-additive in combination in a hard asphalt binder to produce a composite modified asphalt binder. The modification effects of the additives and the influence of different blending protocols were comprehensively studied through laboratory investigations. The rheology of the asphalt binders was evaluated via viscosity, bitumen grading, master curve, Black diagram, isochronal plot, Han diagram, fatigue, creep stiffness and m-value using a bending beam rheometer (BBR), and Multiple Stress Recovery (MSCR) test using a Dynamic Shear Rheometer (DSR). The modified binder's susceptibility to aging effects and thermal stability were also determined by calculation of the aging index (AI) and degree of separation. The results showed that the additives were able to enhance the overall performance of the hard neat Vacuum Tower Bottoms (VTBs) binder by increasing its resistance to rutting, fatigue cracking, and thermal cracking. It was also found that the additives reduced the aging susceptibility of the VTBs binder without any thermal stability or degradation issues after aging conditions. According to the overall performance of the modified binders, a blending protocol for producing a composite modified binder with optimal performance achieved through a well-developed cross-linked polymer elastic network was recommended.