Investigation of the feasibility of using recycled steel fibers in tunnel lining segments

Abstract

Precast concrete segments are mainly loaded by thrust jacks during the installation stage. It is then essential to limit the cracks and damages of the segments during this phase to be sure of their structural integrity and sustainability. Using fibers, the cracks can be better controlled and stabilized in the concrete. It will allow to lead to smaller cracks compared to when using a concrete without fibers. Besides, fibers can help prevent local damages, such as chipping of the edges and segment corners. The main purpose of this study is to evaluate the performance of recycled steel fibers added in concrete to form a segment. To check the effectiveness of recycled steel fibers at the installation stage, a study was performed by using laboratory tests, numerical modeling, an analytical approach, and recommended criteria. In the experimental section, several volume fractions (0, 30, 40, 50, and 60 kgm3 of recycled steel fibers) were used for the tests. Then, compressive strength, splitting tensile, and bending tests were performed. Finally, the results obtained from analytical relationships and numerical modeling were compared with the laboratory results and criteria to evaluate the feasibility of using recycled steel fibers. According to the results, it was found that recycled steel fibers can be used as reinforcement in a hybrid reinforcement (rebars + fibers) to reduce crack width and even rebars consumption to sustain the efforts due to thrust jacks.