Polyurethane-modified asphalt mechanism

With the increasing development of transportation, the demands for the performance and lifespan of asphalt used in road construction have become increasingly stringent. However, most current road asphalt materials exhibit deficiencies in durability. To address the issue of insufficient durability in road asphalt, this paper introduces a novel polymer-modified asphalt utilizing polyurethane as a modifier and investigates the modification mechanism of this asphalt. The feasibility of using polyurethane as a modifier and its effects on matrix asphalt were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. Additionally, molecular dynamics simulations were employed to analyze the radial distribution function, adhesion energy, and cohesive energy density of asphalt before and after the addition of polyurethane at the microscopic structural level, revealing the molecular motion trends and interfacial bonding forces of the four components of asphalt.The results indicate that the incorporation of polyurethane leads to changes in the absorption peaks of matrix asphalt, a reduction in the "honeycomb" structure, and shrinkage. Simultaneously, improvements were observed in the radial distribution function, adhesion energy, and cohesive energy density. These findings suggest that a chemical reaction occurs between polyurethane and matrix asphalt, and the addition of polyurethane effectively enhances the orderliness of asphalt molecules and the interfacial bonding performance.