Application of Fe-C coated LPFG sensor for early stage corrosion monitoring of steel bar in RC structures

Fe-C coated long period fiber grating (LPFG) sensor was employed to monitor the corrosion-induced mass loss of steel bar in 3.5 wt% NaCl solution and steel bar in mortar cylinder. A two-stage process of the change in resonant wavelength as a function of the corrosion-induced mass loss of steel bar was observed. The LPFG sensor can effectively monitor steel bar corrosion loss in 3.5 wt% NaCl solution for 14 h with a sensitivity of 0.124 mg/nm change of the resonant wavelength, and in mortar cylinder for 14 days with a sensitivity of 0.405 mg/nm change of the resonant wavelength, respectively.