The Mechanical Strengths and Resistance to Chloride Salt Erosion of Iron Tailings Powder with Self-Compacting Concrete with Hybrid Fibers

In this study, the fluidity and the flexural and compressive strengths of self-compacting concrete with iron tailings powder are measured. The influence of basalt fibers and steel fibers on the mechanical strengths and the attenuation of performance after NaCl erosion has been investigated. The mass ratio of iron tailings powder ranges from 0% to 20%. The volume ratio of fibers increases from 0% to 3.5%. The influence of hybrid basalt-steel fibers is considered. The results indicate that the mechanical properties vary in the form of cubic functions with the mass ratio of iron tailings powder and the volume ratio of fibers. Specimens with 15% iron tailings powder exhibit the highest mechanical performance. At this dosage, the flexural and compressive strengths are increased by rates of 12.2% and 8.5%, respectively. Specimens reinforced with 2% basalt fibers or 2.5% steel fibers individually exhibit the highest mechanical performance, the lowest chloride ion impermeability, and the best resistance to chloride salt erosion. The hybrid combination of 0.5% basalt fibers and 3% steel fibers provides the optimal fiber dosage. An amount of 2% basalt fibers or 2% steel fibers increase the flexural strengths by rates of up to 48.9% and 84.8%, respectively, while the corresponding compressive strengths are increased by up to 12.5% and 20.9%. The chloride ion migration coefficient of specimens are decreased by up to 37.86%, 30%, and 42.14% with 2.5% basalt fibers, 2% steel fibers, and a hybrid combination of 1.5% basalt fibers and 1% steel fibers, respectively. Specimens with 15% iron tailings powder exhibit the highest amount of dense hydration products and the least amount of cracks.