The mechanical properties of cement mortar reinforced with silica fume subjected to sulfate and chloride environment

This study investigates the effect of incorporating micro-sized silica fume on the mechanical properties and durability of cement mortar when exposed to sulfate and chloride environments. Mortar samples were prepared by replacing cement with micro-sized silica fume in varying proportions of 5%, 10%, 15%, 20%, 25%, 30%, and 35% by weight. The specimens were cured in water and chemically aggressive conditions, including 5% and 10% sodium sulfate solutions, as well as mixtures of 5% and 10% sodium chloride solutions, to simulate real-world exposure to such environments. Experimental results revealed that the addition of silica fume significantly enhanced the mortar's resistance to chemical deterioration caused by sulfates and chlorides. This improvement is attributed to the pozzolanic reaction of silica fume, which contributed to denser microstructures, reduced porosity, and a stronger bond within the matrix. Among the tested proportions, the optimal replacement ratios for achieving the best balance between mechanical strength and durability were identified up to 20%. These findings highlight the efficiency of silica fume as a supplementary cementitious material in mitigating the adverse effects of aggressive chemical agents. Such modifications can be particularly valuable in improving the service life of concrete structures exposed to harsh environmental conditions, enhancing sustainability and cost-effectiveness in construction practices.