Fiber Optic Sensing for Monitoring Corrosion-Induced Damage

This paper reports the feasibility of using embedded Fabry–Pérot fiber optic sensors to detect and monitor the propagation of cracks and delamination within concrete beams induced by corrosion of the reinforcing bars. In this research, four series of reinforced concrete beams were subjected to varying degrees of corrosion-induced damage by modifying the composition of the concrete mix and subjecting all specimens to the same accelerated corrosion environment. The concept employed in this study involves embedding the Fabry–Pérot sensor between two reinforcing bars to measure the transverse tensile strains associated with the longitudinal crack along the reinforcing bars (and in severe cases, delamination of the concrete beam) resulting from the radial expansion of the corroding rebars. Excellent correlation was obtained between the Fabry–Pérot strain data and the amount of steel loss resulting from accelerated corrosion. In addition, the optical sensor strain readings and the reductions in the load-carrying and deflection capacities were also observed to exhibit strong positive correlation highlighting the potential of the optical sensor to monitor the progression of the rebar damage and the loss of structural integrity of the beams resulting from the extensive corrosion. The technique used in this study demonstrates the possibility of detecting corrosion-induced damage in reinforced concrete structures, particularly those where visual inspection is not possible. Keywords fiber optic strain sensor corrosion damage spalling delamination structural health monitoring 1