Influence of sulfuric acid attack on mechanical properties, impact resistance, and electrical resistivity of concrete incorporating microsilica and forta-ferro fibers: Experiments and predictions

• The synergistic effect of microsilica (MS) and forta-ferro (FF) fibers on acid-resistant concrete was experimentally evaluated. • Combined use of MS (7.5–15%) and FF fibers (0.8%) markedly enhanced durability and reduced strength loss. • Individual incorporation of MS or FF fibers alone showed no significant improvement in acid resistance. • Optimized MS–FF combinations improved compressive, tensile, impact, and electrical resistivity performance. • Predictive models were developed to estimate the mechanical properties of concrete under sulfuric acid exposure. Despite the widespread use of concrete in the construction industry, this material exhibits poor performance when exposed to acidic environments, particularly under sulfuric acid attack, where it undergoes progressive deterioration, loss of durability, and reduction in mechanical properties. Therefore, enhancing the acid resistance of concrete remains one of the key challenges in civil engineering. In this study, the combined effect of microsilica (MS) and Forta-Ferro (FF) fibers on the mechanical properties and durability (in terms of physical deformation) of concrete subjected to sulfuric acid attack was investigated. 9 mix designs were prepared with varying levels of MS (0, 7.5, and 15% by cement weight) and FF fibers (0, 0.4, and 0.8% by concrete volume). The specimens were exposed to a 5% sulfuric acid solution for 45 and 90 days and were compared with reference specimens kept in non-acidic conditions. The evaluated parameters included compressive, tensile, impact, and volumetric electrical resistivities as well as physical deformations. The results revealed that the individual use of MS or FF fibers alone provided no significant improvement in acid resistance. However, their optimal combination (7.5–15% MS together with 0.8% fibers) led to a remarkable improvement in durability, a 5–40% reduction in strength loss, and increased stability against acid attack. Optimized additive combinations significantly enhance concrete performance in aggressive environments, offering an effective strategy to improve the durability of industrial infrastructures. Finally, predictive models were proposed for estimating the mechanical properties of concrete incorporating MS and FF fibers under sulfuric acid exposure.