Application of Shotcrete in the Repair and Rehabilitation of Concrete Structures: A State-of-the-Art Review

This state-of-the-art review critically evaluates shotcrete for concrete rehabilitation using an application-based framework covering buildings, bridges, tunnels and underground works, hydraulic and marine structures, and industrial facilities. The review synthesizes deterioration mechanisms, substrate and interface conditions, material and process variables, mechanical and durability performance, quality control, and alternative repair systems. Recent studies are integrated with established guidance and case histories, and quantitative evidence tables are used to facilitate cross-study comparison. Across structural applications, the shotcrete–substrate interface is identified as a critical factor governing rehabilitation performance, with surface condition, moisture state, shrinkage, curing, and environmental exposure affecting bond and durability. The synthesis further demonstrates that performance requirements vary by application, including section restoration, confinement, bond, and durability in buildings and bridges; early-age support, toughness, and residual capacity in tunnels; and low permeability and abrasion/erosion resistance in hydraulic and marine structures. Five research questions are proposed to address key uncertainties in interface behavior, durability, field performance, material development, and quality assurance. The resulting framework provides a systematic basis for evaluating shotcrete rehabilitation strategies and identifying priorities for future research.