Polycyclic Aromatic Hydrocarbons (PAHs) Contamination in the Environment from the Asphalt Concrete Pavement

Asphalt binder, which is the main ingredient of Asphalt Concrete (AC) pavements, is one of the products of crude oil distillation and contains an extremely large number of complex organic compounds as well as cancer-causing substances known as Polycyclic Aromatic Hydrocarbons (PAHs). This research is done to understand possible release and subsequent contamination of PAHs from the AC pavements into the surrounding environment. Molecular Dynamics (MD) simulation is used to understand the release of PAHs regarding energy loss between three PAH molecules Naphthalene, Fluoranthene, and Benzo [a] Pyrene, and two asphalt binder molecules Asphaltene Phenol and Maltene-Aromatic component Dioctyl-Cyclohexane-Naphthalene (DOCHN). Energy loss between PAHs, Asphaltene Phenol, and DOCHN is computed by MD simulation under different climate condition such as varying temperature and moisture, and mechanical conditions such as vehicle tire pressure. MD simulation between PAHs, Asphaltene Phenol, and DOCHN shows that moisture causes significant energy loss and the energy loss indicates a higher potential of releasing PAHs from the AC pavements and contaminate environment. PAHs with lower molecular weight such as Naphthalene have a higher potential to release into the environment than higher molecular weight PAHs such as Benzo [a] Pyrene. Also, it is observed that DOCHN would release more PAHs than Asphaltene Phenol. Although, vehicle tire pressure and temperature influence PAHs release from the AC pavements at various degrees but no consistency is identified. This MD simulation study supports outcomes of previous researchers' experiment completed on PAHs extraction from soil and water collected from AC pavement locations.