Water damage resistance prediction and mechanism of cement/SEBS composite-modified cold-patching asphalt mixture based on molecular dynamics simulation

This study investigated the effect of cement/styrene-ethylene-butadiene-styrene copolymer (SEBS) composite modification on the water damage resistance of solvent-based cold-patching asphalt mixture (CPAM) and its mechanism. Interface behavior of SEBS-modified asphalt and filler oxides (CaO, Al2O3, MgO, SiO2, Fe2O3) under anhydrous/water conditions was investigated by molecular dynamics (MD) simulation, revealing SEBS’s synergistic adsorption of the four components of asphalt on the oxide surface. Quantify the influence of composite modification on free volume fraction and adhesion-peeling mechanisms, predicting optimal cement content. The interface morphology was verified by scanning electron microscopy (SEM), and a correlation equations between CPAM’s water stability indexes and interface energy attenuation ratio (IEAR) was established to validate MD predictions. Results showed that CPAM with a composite modification of 7.5% SEBS and 50% cement exhibited optimal water damage resistance. SEBS significantly improved the interaction between base asphalt binder and filler oxide crystals, especially CaO, Al2O3, and MgO. The mastic – aggregate IEAR decreased by 49% after optimal composite modification. SEM revealed that appropriate cement content facilitated SEBS polymer network formation, boosting mastic-aggregate interface adhesion and verifying the trend of interface water damage resistance with cement content in MD simulation. Under optimal proportion, CPAM’s water damage resistance performance was strongly correlated with IEAR.