Impact failure mechanism and mechanical characteristics of steel fiber reinforced self-compacting cementitious composites containing silica fume

Abstract

An experimental investigation was performed to study the benefits of partially replacing ordinary Portland cement with pozzolanic material on the fresh and hardened characteristics of high-strength self-compacting (HSSC) cementitious composite reinforced by randomly distributed wavy steel fiber. The four wavy fiber volume fractions (0.25%, 0.50%, 0.75%, and 1%) and silica fume contents of 5 and 15 wt% (wt%) of cement were investigated. A total of fifteen mixtures, including different combinations of the fiber and silica fume, were designed and assessed in terms of the passing ability, water absorption, tensile, compressive, flexural, and impact tests. The energy-dispersive X-ray microanalysis (EDX) was applied to specify the cementitious matrix's chemical compositions quantitatively. Moreover, the wavy fiber’s surface topography in the nano-metric scale was specified using an atomic force microscope. The results reveal that the patterns of cracks, impact energy at first crack and failure mechanism, increment in the number of blows after first-cracks, flexural strength, and splitting tensile behavior of mixtures were greatly influenced by adding wavy steel fibers. It was also found that the improvement in toughness and post-peak behavior of HSSC cementitious composites was appreciably governed by the bridging effect of fibers and an increase in bonding strength of interfacial transition zone between fine aggregate and cement paste due to an increase in the content of silica fume. The benefit of the present investigation is to better understand the failure performance of fibrous self-compacting composites.