Comparative study on effects of steel fiber and imitation steel fiber on dynamic tensile properties of ultra-high-performance cementitious composites

Steel fibers (SFs) are commonly used to enhance the performance of concrete. However, they possess limitations such as susceptibility to corrosion, agglomeration during construction and high cost. To overcome these shortcomings, alternative fiber options have been explored. This study investigates and compares the mechanical properties of ultra-high-performance cementitious composites (UHPCC) reinforced with SFs and imitation steel fibers (ISFs). Various tests, including uniaxial compression, quasi-static splitting and dynamic splitting, are conducted to examine the effects of fiber aspect ratio (Lf /df = 20, 30, 40), fiber content (Vf = 0.5%, 1%, 2%) and fiber type (steel fiber and imitation steel fiber) on the force and deformation properties of UHPCC. The test results are analyzed to discern the patterns of tensile strength and energy absorption variations in static and dynamic tensile tests concerning fiber type, aspect ratio and content. Furthermore, the damage process of the specimens is captured using a high-speed camera, enabling the investigation of damage patterns in UHPCC reinforced with different fibers under strain rates of 34-56 s-1 and 109-125 s-1 in dynamic splitting tests. Additionally, fragments generated during impact loading are meticulously collected, sieved and weighed to assess the extent of specimen fragmentation under different splitting load conditions.