Effect of concrete properties and FRP strengthening on rebar mass loss under accelerated corrosion: Experimental investigation and empirical modeling

This study examines the influence of key parameters on the mass loss of reinforcing bars in reinforced concrete (RC) specimens subjected to accelerated corrosion via the impressed-current method, whereas Faraday’s law often fails to predict mass loss in RC specimens accurately. To address this gap, an experimental program was conducted on 24 cubic specimens, each containing four longitudinal rebars. The investigated variables included concrete compressive strength (25 and 40 MPa), concrete cover depth (20, 35, and 50 mm), electrolyte type (sodium chloride or calcium chloride), and exposure duration. The influence of the strengthening method with fiber-reinforced polymer (FRP) was also investigated, using the conventional externally-bonded reinforcement (EBR) and externally-bonded reinforcement on grooves (EBROG) techniques. Results indicated that higher compressive strength and increased cover depth substantially reduced rebar mass loss. Specimens exposed to sodium chloride exhibited greater mass loss than those exposed to calcium chloride. The EBROG method consistently outperformed the conventional EBR technique, resulting in lower mass loss, attributable to improved bonding and reduced microcracking. A novel empirical model was developed through nonlinear regression, integrating experimental data with supplementary datasets from the literature, and validated using 48 independent datasets. The model incorporates concrete compressive strength, cover depth, and the electrochemical exposure index (it/r). The model achieved a coefficient of determination of 97.1%, with 97% of predictions within a 30% error margin, significantly exceeding the performance of Faraday’s law, which yielded an R² of 79.9% and 63% of predictions within the same error margin.