Development of high-performance composite modified emulsified asphalt (CMEA) based on balanced design of compatibility and bonding ability

This study aims to develop a high-performance composite modified emulsified asphalt (CMEA) with excellent compatibility and bonding ability. Firstly, the modification mechanism of CMEA was elucidated through Fourier transform infrared spectroscopy (FTIR). Secondly, the compatibility of CMEA was systematically evaluated by storage stability, particle size distribution and Fluorescence microscopy (FM). Finally, the bonding ability was assessed via binder bonding strength (BBS) tests, and the compatibility indicator most correlated with bonding ability was determined via grey relational analysis (GRA). The results demonstrated that styrene-butadiene rubber (SBR) and waterborne epoxy resin system (WERS) would construct a flexible-rigid network structure by physical blending behavior, while silane coupling agent (SCA) would enhance the structural stability and interfacial adhesion ability through chemical interactions. Low dosages of WERS and SCA fail to establish an effective structural network, while excessive amounts would lead to rigidity-dominated behavior and hinder the uniform dispersion of modifiers, thereby compromising the interfacial interaction. Considering the balance of compatibility and bonding ability, the dosages of WERS and SCA should be controlled within 10 % and 1.5 %, respectively. Temperature-dependent results further revealed that the 10 % WERS/1.5 % SCA formulation is more suitable for high-temperature conditions, whereas 10 % WERS without SCA performs better under low-temperature conditions. The balanced consideration on smaller particle size distribution and greater bonding ability should be prioritized since which shows the highest correlation in the design of high-performance CMEA. • Physical blending and chemical reactions coexist in the SBR/WERS/SCA CMEA system. • Particle size shows the strongest correlation with bonding performance in CMEA. • SBR–WERS interactions are both synergistic and competitive, modulated by SCA dosage. • Proper WERS and SCA dosages improve interfacial bonding and compatibility, while excess reduces performance.