Concrete fracture process zone characterization with fiber optics

The characterization of the fracture process zone inside a cracked concrete specimen is investigated through optical fiber technology. Fiber Bragg gra tings are used to measure the strains in the close vicinity of the crack fr ont, thus enabling us (for the first time) to directly measure those deform ations inside the concrete specimen. A detailed discussion of the experimen tal technique is first provided. Then, following the experimental measureme nts, test results are presented and discussed. Preliminary results indicate that there is a narrow zone on each side of the crack front with inelastic residual strains, and another when strains increase only in the presence o f a neighboring crack tip. The width of the process zone is found to be abo ut three times the maximum aggregate size.