Assessing the effects of sunlight and water on asphalt binder and pavement leachability related to the environment

Extensive global research conducted over 30 years explores asphalt leachability and stormwater runoff. Asphalt's widespread usage in construction materials underscores the importance of understanding its environmental consequences. This study aims to assess the influence of sunlight exposure on water quality, particularly regarding the release of hazardous organic compounds such as polycyclic aromatic compounds. We investigated the effect of concurrent versus sequential exposure to water and sunlight, and dark versus light trials utilizing thin films of asphalt binder as well as old and freshly prepared pavement cores for analysis. Initial laboratory experiments reveal significant water-soluble species when thin asphalt films are exposed to solar simulation while underwater. However, simulating environmental conditions found in roadways by exposing the asphalt binder to solar simulation followed by water immersion leads to a substantial decrease in compound formation. Leachate water from 17-year-old asphalt and 15-year-old concrete pavements exhibits complex compound compositions associated with atmospheric and/or vehicular deposition, posing challenges in deconvoluting their origins. Light and dark trials conducted on freshly prepared asphalt pavement under environmental conditions of sunlight and rain demonstrate minimal runoff variation, with semi-volatile organic compound levels resembling the background. Future investigations will focus on applying insights gained from this study to analyze larger sample sets, with an emphasis on inherent hazardous compound variations.