The effect of hybrid steel fiber on the properties of fresh and hardened self-compacting concrete

Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel fibers extends its possibilities. This study was performed to compare the properties of SCC and fiber reinforced self-compacting concrete (FRSCC) with high volume of mineral addition. Six mixtures were elaborated in this study. The content of the cementitious materials and the water/cementitious materials ratio were kept constant, 500 kg/m3 and 0.34 respectively. The self-compacting mixtures have been prepared with a cement replacement of 30% by weight of marble powder. Two different types of steel fibers were used in combination with different lengths (50 mm and 30 mm), keeping the total fiber content constant at 60 kg/m3. Slump flow time and diameter, sieve stability, and L-Box were performed to assess the fresh properties of the SCC and FRSCC. Compressive strength, splitting tensile strength, flexural strength and ultrasonic pulse velocity were determined for the hardened properties. A marginal improvement in the ultimate strength was observed. The addition of steel fiber enhanced the ductility significantly and the results indicated that high-volume of marble powder can be used to produce FRSCC, even though there is some decrease in the compressive strength because of the fiber geometry which affects the properties of SCC mixtures not only in the fresh state but also in the hardened state.