Chloride transport dynamics in sound and cracked concrete under counter-advective flow across multiple marine zones

Chloride transport dynamics in concrete depend on a complex interplay between diffusion and advection, a process further complicated by material cracking and varied environmental exposures. In this study, these dynamics were investigated under the influence of a pressure-induced counter-advective flow, generated by the Reverse-seepage and Saturation based Active Anti-corrosion Technology. Indoor accelerated tests, complemented by numerical simulations, were conducted on both sound and cracked concrete (crack widths up to 150 μm) across simulated submerged, tidal, and splash zones. The results revealed that the outward counter-flow consistently mitigated chloride ingress by physically opposing the inward transport. This protective mechanism was effective across all exposure zones, substantially diminishing the large performance disparities typically observed between them. Furthermore, the counter-flow effectively counteracted the accelerated transport along preferential pathways in cracked concrete, confirming its efficacy in compromised material. This work provides an experimentally validated, physical understanding of controlled chloride transport in concrete under a uniquely broad range of challenging conditions.