This study investigates the mechanical properties and performance of three concrete grades—C50, C35, and C20—focusing on compressive, tensile, flexural, and shear strengths of both plain and fiber-reinforced concrete. The specimens were tested with a constant aspect ratio of 65 and varying fiber volumes (0.5%, 1%, 1.5%, 2%, 2.5%, and 3% of the concrete volume) along with the addition of micro silica. The water-to-cement ratio was 0.50 for C20 concrete and 0.44 for both C35 and C50 concrete mixtures. Results revealed that increasing the fiber volume from zero to three percent significantly improved mechanical properties, with the most substantial effects observed at 1.5% fiber content, showing increases in flexural strength by up to 54% in C50 and 144% in C20. Furthermore, the combination of steel fibers and micro silica enhanced the shear strength by up to 115% in C50 and led to significant improvements in sulfate resistance and freeze–thaw durability and a 38% to 42% reduction in freeze-thaw damage across various grades. Additionally, micro silica reduced slump, indicating improved control over the concrete's workability. This combination significantly improved the durability performance of concrete under sulfate exposure and freeze–thaw conditions, making it suitable for structures subjected to aggressive environmental conditions, making the fiber and micro silica reinforced concrete suitable for structures exposed to dynamic loads and harsh environmental conditions. The results provide a comprehensive comparison of the combined influence of concrete strength grade, hooked-end steel fiber volume fraction, and microsilica on both mechanical and durability-related properties, thereby contributing to the optimization of steel fiber-reinforced concrete mixtures for structural applications.