Characterizing the Interaction Mechanism between Asphalt and Mineral Filler in Asphalt Mastics of Mastic Asphalt Concrete Using Rheological Analysis, Hirsch Model, and 3D DEM

Asphalt binder and mineral filler are key components that significantly affect the properties of mastic asphalt (MA) mixtures. Asphalt mastic, formed by mixing mineral filler and asphalt binder, offers an effective way to study their roles within the MA system. This study focuses on mineral filler and asphalt binder, using asphalt mastic as the entry point to thoroughly investigate their functions in MA concrete. Rheological experiments and the discrete element method (DEM) were combined to analyze and validate the interaction between mineral filler and asphalt binder. The Hirsch model was used to quantitatively assess their mechanical interaction in the MA system. Results indicate that increasing both Trinidad Lake asphalt (TLA) and mineral filler content raises the complex modulus and reduces the phase angle of asphalt mastic. The Hirsch model shows that TLA content mainly affects high-temperature properties, while filler content has a greater impact on low-temperature properties. Mineral fillers contribute more than half of the resistance to external loads, with their effect increasing as filler content rises. Simulations reveal that although the asphalt binder bears larger forces, the filler ultimately withstands more force under external loading. The binder primarily distributes the force to the filler, ensuring uniform stress. This comprehensive investigation clarifies the interaction mechanism between asphalt binder and mineral filler in MA concrete through experiments, modeling, and simulations.