Mechanical properties of steel fiber reinforced concrete (SFRC) mixed with NaCl solutions of varying concentrations

Steel fiber reinforced concrete (SFRC) specimens were prepared using NaCl solutions of varying concentrations (0, 3, 6, and 9 wt%) as mixing water. Over a 14-month exposure period in a high-humidity environment (RH≥95%), the cubic compressive strength, flexural properties and splitting-tensile properties of SFRC were monitored. Results demonstrated that the steel fibers inside concrete were hardly corroded, and only a few rust spots were found on the surface of specimens. The mechanical properties of chloride-mixed SFRC did not decrease but instead improved after 14 months of exposure. In which, the compressive strength increased by 15.5%, the flexural toughness improved by 10.6–20.7%, and the splitting-tensile strength rose by 12.9–23.8%. SFRC demonstrated exceptional chloride tolerance, maintaining mechanical integrity with NaCl solutions as mixing water. The results validated the technical viability of seawater-mixed SFRC for marine infrastructure, eliminating freshwater dependency while ensuring the durability.