Measuring Corrosion of Steel in Concrete via Fiber Bragg Grating Sensors—Lab Experimental Test and In-Field Application

In this paper, a new corrosion sensor using fiber Bragg grating (FBG) to monitor corrosion of steel rebars embedded in concrete structures is presented. The mechanism is based on the fact that the increase in the diameter of the reinforced steel due to corrosion can be obtained by detecting the strain variation of the optical fiber using FBG. The corresponding experimental results indicated that this new type of corrosion sensor can be effectively used for monitoring the early corrosion of a rebar, and the degree of corrosion can also be manifested. Finally, this type of sensor is applied to monitor the corrosion of steel rebars in Xiang 'an Sub-sea tunnel, which has the largest cross-section among all the sub-sea tunnels in China.