Microscopic mechanism and effect analysis of polymer modifiers on embrittlement and viscosity behaviour of asphalt

To support the research and development of asphalt binder with low embrittlement point in cold areas, the microscopic mechanism and effect of polymer modifier on embrittlement and viscosity of asphalt were analysed by molecular dynamics method. The mixed molecular models of three polymer modified asphalt commonly used in cold areas and the interactive molecular models of each component of asphalt and modifier were established. The micromechanical properties of high-content polymer modified asphalt were studied by three important indices, namely brittleness point, shear viscosity and elastic modulus, and the interaction behaviour of each component of asphalt and modifier molecules was analysed by the layer model. The following conclusions were obtained: The brittleness point of modified asphalt can be decreased by increasing the polymer modifier content, with a notable reduction of 25.54% observed when the content reaches 7.5%. However, this is accompanied by a subsequent increase in shear viscosity at mixing temperatures, with the highest increase reaching 16.9%. At low temperature environment, the diffusion rate of the modifier is closely related to its own type, temperature and the type of asphalt components, and in different modified asphalt, the law of the diffusion rate of each asphalt component is not completely consistent, so it is necessary to fully consider the influence of the proportion of asphalt components, and choose the modifier sensitive to the corresponding components. The above research results have an important guiding role in the scientific formulation of the design and test scheme of low-brittleness-point asphalt binder and the completion of the research and development of low-brittleness-point asphalt binder for cold areas.