关键词: 道路工程;纳米ZnO;沥青分子模型;分子结构;物理性能;分子动力学

Abstract: In order to reveal the mechanism of nano-ZnO modifier improving the physical properties of asphalt, the molecular dynamics simulation technology was used to simulate nano-ZnO modified asphalt. The asphalt molecular model was constructed by the representative compounds of four fractions of asphalt, combined with the test results of element content of matrix asphalt and the relative content of four fractions. Models of nano-ZnO with different particle sizes and nano-ZnO/asphalt blends were built according to the morphological characteristics of nano-ZnO. The interaction between nano-ZnO and asphalt molecules was calculated by molecular dynamics method, and the diffusion properties of nano-ZnO in asphalt were analyzed. Moreover, the influence of nano-ZnO on physical modulus and the molecular structure of asphalt was investigated. According to the molecular dynamics simulation results, the modification mechanism of nano-ZnO modified asphalt was revealed. Research results show that when the simulation temperature is about 150 ℃, the van der Waals interaction and non-bonding interaction of nano-ZnO/asphalt blends reach the maximum, whose architecture is the most stable. Nano-ZnO particles increase the bulk modulus, shear modulus and elastic modulus of asphalt system and improve the high temperature performance of asphalt, so as to improve the shear resistance of asphalt. Meanwhile, nano-ZnO enlarges the centroid distance between asphaltenes and resins system molecules, alleviates of the accumulation of strong polar fractions, strengthens the ductility of branched chains between molecules and increases the compactness of asphalt structure, which contributes to a more stable colloidal structure and better physical properties of asphalt.

Key words: highway engineering; nano-ZnO; asphalt molecular model; molecular structure; physical properties; molecular dynamics