Effect of Acid Rain on Mechanical Properties and Aging Mechanism of Asphalt

Through the preparation of nitric acid–type acid rain, mixed acid rain, and sulfuric acid–type acid rain, an experimental method of periodic soaking of asphalt was developed. Then, using a four-component test, the four-component mass fraction of aging asphalt was obtained. The change characteristics of functional groups of aged asphalt were analyzed using infrared spectroscopy, and the aging mechanism of aged asphalt was analyzed using differential scanning calorimetry. Based on molecular dynamics theory, the bulk modulus and shear modulus of aged asphalt were calculated by establishing a molecular model of acid rain and a molecular model of aged asphalt. The diffusion coefficient, cohesive energy density, solubility, and other parameters of the aging asphalt molecular model were calculated. The influence of acid rain on the mechanical properties of asphalt was explored at the molecular level, and the mechanism of acid rain aging asphalt was explored. The results show that sulfuric acid–type acid rain has the greatest impact on the mechanical properties of asphalt and causes the most serious aging of asphalt, followed by mixed acid rain, and nitric acid–type acid rain has a relatively small impact on the mechanical properties of asphalt and the aging of asphalt.Practical ApplicationsThe research in this paper clarified the influence of acid rain on the mechanical properties of asphalt and the aging mechanism of acid rain on asphalt. This research conclusion can be applied in the evaluation of asphalt pavement performance degradation in acid rain area.