The effects, mechanisms, and environmental impacts of SBS polymer in mitigating organic emissions from base asphalt

Asphalt mixtures could emit substantial organic compounds during production and construction, posing potential health risks and potentially degrading asphalt binder performance. However, it remains unclear whether polymer modification can alter these emissions. This study systematically assesses how styrene–butadiene–styrene (SBS) modification influences the effects, mechanisms, and environmental impacts of organic emissions from base asphalt, using an integrated approach spanning environmental science, toxicology, chemistry, surface science, and rheology. The results show that SBS polymer effectively reduces emissions of multiple organic compounds and suppresses the formation of secondary air pollutants, odor nuisance, and human health risks. Among the tested dosages, a dosage of 4.5% SBS leads to the greatest mitigation effect. Based on compound identification and prior literature, secondary pollutant formation and odor nuisance are driven mainly by certain n‑alkanes, whereas health risks are predominantly associated with polycyclic aromatic hydrocarbons (PAHs). Beyond mitigating environmental and health risks, SBS polymer improves asphalt binder performance, including surface free energy characteristics, rheological behavior, and structural phase transitions. These benefits are likely attributed to the unique network structure and physical cross‑linking between SBS and asphalt binder. Overall, the findings elucidate the effects, mechanisms, and environmental implications of SBS modification that reduces organic emissions from base asphalt, thereby advancing the development of cleaner, high‑performance, sustainable, and health‑protective paving materials and technologies.