Use of WLI and FBG Technique to Monitor the Residual Strains of Concrete Caused by Freeze-Thaw Damage

Abstract

In this study, Fiber Bragg grating (FBG) and white light interferometer (WLI) sensing technique are introduced and used to monitor the concrete residual strain caused by freeze-thaw damage. Concrete specimens wrapped with optical fiber are subjected to multiply cycles of freezing and thawing. Expansion strain of concrete caused by freeze-thaw damage in real-time. The test results show that, the residual strain sensitively measured by optical fiber sensors was basically fitted with the phenomenon that the residual strain increased along with the number of freeze–thaw cycles, and indicate that two fiber sensing techniques were able to monitor the concrete freeze–thaw damage. Meanwhile, comparing the two techniques from four aspects, WLI was more suitable for residual strain monitoring in concrete freeze–thaw damage.