Study on the Volatile Organic Compound Emission Characteristics of Crumb Rubber-Modified Asphalt

Crumb rubber used in asphalt modification can generally improve the road performance of asphalt mixture pavement while offering substantial environmental and economic benefits. This study investigates the volatile organic compound emissions from crumb rubber-modified asphalt binders via gas chromatography–mass spectrometry, focusing on the effects of crumb rubber types (e.g., activated crumb rubber, non-activated crumb rubber), contents, and additives (warm-mix agents, deodorants, styrene–butadiene–styrene (SBS)). The analysis encompasses total volatile organic compound emissions, compositional variations, secondary organic aerosol and ozone formation potentials, and carcinogenic risks. Results indicate that non-activated crumb rubber increases volatile organic compound emissions initially, peaking at a 15% content (3.99 times higher than base asphalt), dominated by trichloroethylene. The surfactant-based warm-mix additive significantly reduces emissions by 73%, whereas deodorants exhibited limited efficacy. At equivalent contents, activated crumb rubber-modified asphalt emits more volatile organic compounds than non-activated crumb rubber-modified asphalt and leads to a higher ozone formation potential. Activated crumb rubber/SBS-modified asphalt blends reduce emissions by 69%–81% due to synergistic effects. In contrast, non-activated crumb rubber/SBS blends increase emissions, likely due to phase separation. All samples contain carcinogens, primarily trichloroethylene (20%–79%) and benzene (0.1%–9%). These findings underscore the critical importance of crumb rubber activation status and SBS addition in controlling volatile organic compound diffusion. The activated crumb rubber/SBS combination achieves a synergistic reduction exceeding the sum of individual effects (“1 + 1 > 2”). These findings provide valuable insights for designing eco-friendly asphalt.