Advances in the understanding of corrosion and performance of hot-dip galvanized rebar in concrete structures

Corrosion of reinforcing steel remains one of the most pressing durability challenges for concrete infrastructure, with substantial economic and safety implications. This review provides a systematic and critical synthesis of research on hot-dip galvanized (HDG) reinforcement, integrating electrochemical, structural, and field-based perspectives. The methodology involved comparative evaluation of laboratory studies, long-term monitoring data, and technological advances to identify consensus findings and unresolved controversies. The novelty of this review lies in its focused analysis of three critical debates: the influence of initial hydrogen evolution on interfacial bond strength, the conditional stability of the calcium hydroxyzincate passive layer in high-alkalinity environments, and the discrepancy between accelerated laboratory testing and field performance. The review also compares HDG with alternative reinforcement systems, particularly epoxy-coated and stainless steel rebars, to contextualize durability and cost trade-offs. Recent innovations, including continuous galvanized rebar (CGR), zinc-alloy modifications, non-destructive evaluation methods, and computational service-life modeling, are highlighted as transformative developments. By systematically bridging mechanistic insights with practical outcomes, this review advances current understanding of galvanized reinforcement and identifies critical directions for future research aimed at reliable service life prediction and optimized application in durable concrete structures.