Experimental investigation on chloride resistance of ECC and numerical simulation of chloride transport behavior after surface-bonded CFRP under chloride salt dry-wet cycles

Reinforced concrete structures located in marine tidal and splash zones are susceptible to chloride-induced deterioration under frequent dry-wet cycles, leading to performance degradation. Engineered Cementitious Composites (ECC), due to their high ductility and excellent crack control capacity, exhibit superior durability compared with conventional concrete. This study experimentally investigated the mechanical performance of ECC under chloride dry-wet cycles and analyzed its chloride transport behavior by combining laboratory tests with numerical simulations. Results showed that after 180 days of cyclic exposure, the compressive and flexural strengths of ECC increased by approximately 21.51 % and 34.94 %, respectively, compared to the initial values, while the tensile strength remained essentially stable throughout the test period. Moreover, externally bonded Carbon Fiber Reinforced Polymer (CFRP) effectively reduced the free chloride ion concentration within the specimens, thereby enhancing resistance to chloride ingress. This study proposed multi-factor influenced chloride transport models based on Fick’s second law, which showed good agreement with experimental results. Moreover, a mesoscale numerical model, developed in this study through secondary development of ABAQUS using Python and FORTRAN, was also in good agreement with both experimental data and analytical solutions. Parametric analyses further revealed the key factors influencing chloride diffusion at the mesoscale. The findings provide theoretical support for the durability design and service-life prediction of marine concrete structures, as well as practical guidance for optimizing anti-chloride ingress strategies in engineering applications. • Mechanical properties and chloride transport of ECC studied under dry-wet cycles. • Effects of PVA fibers and CFRP bonding on chloride resistance of ECC investigated. • Multi-factor chloride transport model with CFRP developed and experimentally verified. • ABAQUS secondary development using Python/Fortran for chloride diffusion simulation.