Damage Detection of Carbon Fiber-reinforced Concrete Under Bending Test

Nowadays, fiber-reinforced concrete plays a vital role in the construction industry due to its superior mechanical properties, corrosion resistance, and light weight characteristics.Thanks to the partial penetration of fine-grained concrete within the bundle of fibers, ductile behavior of fiber-reinforced concrete can be anticipated. In this capacity, the bundle of fibers is divided into two distinct areas namely, the fibers embedded into concrete,which is called as sleeve fibers, and dry fibers which are supposed to behave as core fibers. Accordingly, estimating the number of sleeve fibers and distinguishing their damages when the fiber-reinforced concrete is subjected to load service are the main scopes of this study. Electrical resistance of roving was measured by Wheatstone bridge technique to detect fiber damage during bending of fiber-reinforced concrete beam. Besides, the number of sleeve fibers on the roving cross-section was estimated using SEM images and was correlated with the changes in the electrical resistance of roving. The results indicate that the sleeve fibers fail with a distinctive delay after the occurrence of the first crack, while the core fibers remain sound. Eventually, it is demonstrated that the proposed methodis capable of estimating the number of damaged fibers during bending test, and also evaluating the penetration of the cement matrix within the bundle of fibers.