Investigating the effect of sulfate attack on the durability of cement composite reinforced with steel fibers and polypropylene containing silica nanoparticles

The present study investigates the impact of sulfate attack on the durability of reinforced ‎cement composites containing steel and polypropylene fibers, as well as silica nanoparticles. ‎To this end, varying weight percentages (1%, 2%, and 3%) of silica nanoparticles replaced ‎cement, and 1% by weight of steel fibers and 0.2% by weight of polypropylene fibers were ‎separately and concurrently added as micro-scale additives to the cement composite exposed ‎to sulfate attack. Consequently, the formulated cement composites underwent a 6-month ‎exposure to a 5% sodium sulfate solution, and the effects of the sulfate environment on ‎changes in compressive strength, weight, and longitudinal expansion of the specimens were ‎studied. The results indicate that the simultaneous presence of silica nanoparticles, steel ‎fibers, and polypropylene leads to increased durability against sulfate attack. Specifically, ‎the composite with 2% silica nanoparticles, 1% steel fibers, and 0.2% polypropylene fibers ‎exhibited the least reduction in compressive strength, mass loss, and longitudinal expansion ‎after 6 months of immersion in the sulfate solution compared to other formulations. ‎According to the findings, the concurrent presence of silica nanoparticles and steel and ‎polypropylene fibers in the cement matrix significantly enhances the durability of cement-‎based composites against sulfate attack.‎