Multiscale analysis of epoxy asphalt curing behavior based on molecular dynamics simulation and experiments

The curing behavior of epoxy asphalt (EA) and its performance regulation mechanisms remain incompletely understood, which limits both material optimization and engineering applications. In this study, EA molecular models covering different epoxy system (ES) contents and curing degrees were constructed, the dynamic curing process was simulated using a Perl cross-linking script, and the reliability of the model was verified. Through a series of macro- and micro-scale tests, the curing kinetic parameters, characteristic group conversion, component distribution, and viscosity evolution during the curing process were analyzed. Additionally, high-precision simulation methods suitable for EA viscosity were compared and selected. The results indicated that the curing process of the ES follows an autocatalytic reaction mechanism, and under 60 ​°C isothermal curing conditions, the primary curing reaction is essentially completed within 24 ​h. The ES content significantly influenced the phase morphology, leading to a "sea-island structure" at high contents. As the ES content increased, the system viscosity rose notably, but temperature played a dual regulatory role: it accelerated the chemical curing reaction rate while significantly lowering the base viscosity of the system by enhancing molecular mobility. Molecular dynamics simulations further confirmed experimental results, revealing network formation at the molecular scale and the close correlation between component compatibility and macroscopic properties. Moreover, the Stokes-Einstein viscosity model achieved effective and reliable prediction during the high-temperature, pre-gelation stage. These findings provide a theoretical basis for optimizing EA formulations and construction parameters, offering important guidance for developing high-performance road materials.