Optimising bitumen modification: how styrene–butadiene–styrene (SBS) characteristics and content affect bitumen behaviour

To enhance the performance of bitumen, especially in the critical low/high temperature regions and under heavy traffic loading, polymer-modified binders are used to produce asphalt mixtures. Styrene–Butadiene–Styrene (SBS) is the most common polymer modifier. Although numerous studies tried to capture the effect of SBS on bitumen performance, yet a comprehensive chemomechanical investigation considering the synergistic effect of base bitumen, SBS content and type is missing. This study aims to fill this research gap and provide practical recommendations on how to optimise bitumen modification for polymer-modified binders. For this purpose, three base binders were modified with four SBS polymers, which differ in structure (linear vs radial) and styrene/butadiene ratio. Two modification levels were applied at each ase binder. Overall, 14 PMBs were produced and subjected to comprehensive chemomechanical testing. The results showed that an optimum PMB can be produced by focusing on three main aspects: saturates, recovery and creep compliance and G-R values.