Molecular dynamics simulation of chemical structure evolution and dry adhesion characteristics of diatomite-asphalt interface

Abstract

To maximize the processing and utilization efficiency of diatomite ore while minimizing its negative impact, and to provide practical guidance for engineering applications by controlling the dosage of diatomite in production, this study investigates the influence of the main chemical components of diatomite on the water stability of asphalt mixture. Standard Marshall test, immersion Marshall test, and freeze-thaw splitting test were conducted to evaluate the stability, flow value, and related indexes of AC-20 asphalt mixture modified with diatomite from four different producing areas. Grey correlation analysis was employed to examine the effect of the main chemical components of diatomite on the water stability of the modified asphalt mixture. The internal mechanism by which diatomite improves the water stability of pavement was further analyzed using scanning electron microscopy. In addition, based on molecular dynamics theory, the interfacial energy between the chemical components of diatomite and the main components of asphalt was qualitatively and quantitatively calculated, which reveals the dry-state adhesion characteristics at the diatomite-asphalt interface. The results show that adding diatomite through the method significantly improves the water stability of asphalt mixture. Among the chemical components, the content of Al₂O₃ is found to have the greatest influence on the water stability of diatomite-modified asphalt mixture. The molecular dynamics simulations demonstrate that strong dry-state interfacial adhesion is established between diatomite components and asphalt, which provides a mechanistic basis for the observed enhancement of water stability in macroscopic tests.