Investigating the influence of nano-silica incorporation on mechanical characteristics of steel fiber-reinforced concrete to mitigate solid waste and environmental contamination

Using nano-silica and steel micro-fibers in high-strength concrete has gained attention due to their potential to reduce solid waste and environmental pollution. In this study, the impact of nano-silica inclusions on the mechanical properties of steel fiber-reinforced concrete, referred to as "Micro-Concrete Reinforced with Steel Fibers Embedding Nano-Silica" (MRSFEN), was assessed. MRSFEN mixtures were prepared with 0%, 1%, and 2% nano-silica content and 0.5%, 1%, 2%, and 3% steel micro-fiber content. Tests showed a 17%-32% increase in compressive strength and a 12%-29% increase in tensile strength by adding 1%-2% nano-silica across all fiber contents. Incorporating 1%-3% steel micro-fibers resulted in 18-25 MPa higher compressive strength, 6-12 MPa higher tensile strength, and 10%-35% higher flexural strength relative to non-fiber concrete. However, workability reduced by 15%-30% with 3% fiber content. The combined use of nano-silica and steel micro-fibers enhanced strength and ductility, with the optimum composition identified as 1% nano-silica with 2% steel micro-fibers based on the mechanical performance. The results indicate the potential of tailored MRSFEN mixtures to improve the mechanical properties of steel fiber-reinforced concrete, with benefits in reducing solid waste and mitigating environmental contamination.