Research on Working and Mechanical Properties of Self-Compacting Steel-Fiber-Reinforced High-Strength Concrete

This paper discusses the potential of using steel fiber to produce self-compacting high-strength concrete. The effects of water–binder ratio and mortar and steel fiber content on the workability and mechanical properties of high-performance concrete were studied. The working performance of cementitious materials was evaluated by a slump expansion test, T500, L-shaped instrument, U-shaped instrument, and V-shaped funnel. The mechanical properties were evaluated by compressive strength and flexural strength. The results show that when the compressive strength of self-compacting high-strength concrete with steel fiber is 90 MPa, the optimum mix ratio is a water–binder ratio of 0.22, sand ratio of 46%, and steel fiber content of 0.3%. When the steel fiber content is 0.3%, the compressive strength of the time can be increased by more than 4%, and the flexural strength can be increased by more than 5%. When the steel fiber content is 0.6% to 0.9%, the compressive strength of the specimen can be increased by more than 10%, and the flexural strength can be increased by more than 7%. However, with the increase in steel fiber content, self-compacting concrete becomes less and less dense, and the bond strength becomes lower and lower. When the water–binder ratio is 0.20, the fluidity of self-compacting concrete is poor, and the forming effect is not good. When the water–binder ratio is 0.24, the working performance of self-compacting concrete is better, but the cohesion is poor, and it can easily produce segregation. When the water–binder ratio is 0.22, the working performance of self-compacting concrete can be the best, and the strength of concrete is higher and more stable. The optimum sand ratio is 46%. At this time, the compressive strength and flexural strength of self-compacting concrete are the largest, and the working performance is also the best. When the sand ratio is lower than the optimum sand ratio, the self-compacting concrete will produce segregation. When the sand ratio is higher than the optimum sand ratio, the fluidity of self-compacting concrete is poor. This study provides insights into the potential for large-scale and high-value utilization of steel fibers and the development of cost-effective ways to reduce the carbon footprint of self-compacting concrete production.