A review on fiber optic sensors for rebar corrosion monitoring in RC structures

Reinforcement steel corrosion is one of the major causes of premature deterioration of concrete structures in marine environments or subjected deicing salts. Steel corrosion causes economic loss and even results in structural collapse and consequently loss of human life. Various optical fiber sensors have been proposed to monitor steel rebar corrosion in concrete structures over the past two decades due to light weight, compactness, small size, immunity to electromagnetic interference, and capacity of being multiplexed into a sensor network. This study presents a state-of-the-art review of optical fiber sensors for corrosion monitoring of reinforcement steel in concrete structures with emphasis on sensing principle and performance parameters including measurand, sensitivity, monitoring range and service life. The optical fiber corrosion sensors reviewed in this study mainly include fiber Bragg grating (FBG) based corrosion sensors, long-period fiber grating (LPFG) corrosion sensors, extrinsic Fabry-Perot interferometer (EFPI) corrosion sensors, Brillouin backscattering-based distributed fiber optic corrosion sensors, optical frequency domain reflectometry (OFDR) corrosion sensors, and other fiber optic corrosion sensors. This review aims to clarify performance and limitations of fiber optic sensors for reinforcement steel corrosion monitoring in concrete for the purpose of providing a foundation for future research and engineering applications.