Functional design of warm mix additives and its influence on the performance of high-content SBS-modified asphalt

FT wax is one of the most widely used organic warm mix additives due to its ability to significantly reduce the mixing and compaction temperatures of asphalt mixtures. However, its use is often accompanied by challenges, including poor compatibility with asphalt binders and the degradation of low-temperature performance. These limitations have hindered the widespread adoption of FT wax-based additives. In this study, a novel FT-wax-based warm mix additive, referred to as warm mix additive B (A graft copolymer synthesized by chemically grafting FT wax with styrene and ethylene glycol dimethacrylate, designed to improve both compatibility and low-temperature performance compared with conventional FT wax), was designed and developed through molecular dynamics simulations and laboratory synthesis. The simulations provided valuable insights into the molecular behavior and interactions between the FT wax and asphalt components, leading to the successful formulation of the new additive. Experimental results showed that the viscosity of asphalt containing warm mix additive B was reduced by 38.7 % compared to conventional SBS-modified asphalt. This viscosity reduction was 5–10 % greater than that achieved with other commercial warm mix additives, and it further allowed the construction temperature to be lowered by approximately 15–20 °C, thereby reducing construction energy consumption and simultaneously decreasing carbon emissions, which highlights both economic and social benefits. In addition, warm mix additive B exhibited significantly improved compatibility with the asphalt binder, enhanced low-temperature performance of the asphalt binder by more than 20 % compared to other commercial warm mix additives, and improved high-temperature performance of the asphalt binder by approximately 15–20 % relative to conventional SBS-modified asphalt. • A novel warm mix additive was developed to balance high-temperature stability and low-temperature performance. • Its performance was evaluated using molecular dynamics simulations combined with laboratory experiments. • The additive effectively improved workability and reduced energy consumption in high-content SBS-modified asphalt. • A design strategy was proposed for targeted performance enhancement through functional group grafting.