Asphalt pavement emission behavior under solar radiation during in-service period

The toxic fume emitted from asphalt pavement remains a health and environmental hazard towards public safety, especially the emission of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Despite extensive studies focused on characterizing asphalt fumes generated during construction stages (i.e. 150-180°C) have already been conducted, the long-term emissions induced by solar radiation during its service life are relatively unexplored (i.e. 60-70°C), especially the emission composition trends and their relationship with asphalt composition. In this study, three commonly used asphalt were aged with different accelerated aging durations, and their emissions of different asphalt compositions under artificial solar radiation and 70°C heating were analyzed and compared. During the aging process, the asphalt generally emitted alkanes (C₁₂ - C₂₀), monocyclic benzene series and PAHs, which positively correlate with the contents of aromatic and saturate fractions. Compared to 70°C heating condition, the artificial solar radiation promoted the release of additional pollutants, including PAHs (i.e., anthracene, phenanthrene), cycloalkanes (C₁₄ - C₂₅) and long-chain alkanes (C₁₅ - C₁₈). Moreover, the asphalt emissions during service life exhibit a quadratic reduction relationship with longer aging durations. The results reveal the asphalt emission behavior under solar radiation, indicating potential emission pollutants during asphalt pavement service life.