Styrene-Butadiene-Styrene polymer modified bitumen: A review on compatibility and physico-chemical properties

The triblock elastomeric copolymer Styrene-Butadiene-Styrene (SBS) improves the engineering properties of bitumen and the performance parameters of flexible pavements. Although research investigations have been conducted worldwide, the literature lacks a comprehensive review to provide the up-to-date research status in this field. The current review summarizes the research findings on the compatibility, stability, physical properties, microscopic characterization, and chemical characterization of SBS modified bitumen. Quantitative analysis of physical test results concerning major pavement distresses shows improvement, particularly in high-temperature zones. The interlocked state of phase transition can be achieved at SBS content between 5%-6% and the optimum SBS content has been reported to lie within this range. The blending temperature of SBS modified bitumen varies between 140 degrees C-210 degrees C out of which 180 degrees C is the most frequently used by researchers. In addition, physical and chemical characteristics of aged binder have been reviewed. Aging indices (residual penetration ratio, change in softening point, viscosity aging ratio, residual ductility ratio) didn't show any consistent trend, which establishes the need of exploring the co-additives to substantially improve the aging deterioration. Preliminary research on nano-additives showed the improved storage stability at high temperature and the performance of aged modified bitumen. This review has drawn essential conclusions and highlights existing research gaps for peer researchers and field engineers.