PERFORMANCE EVALUATION AND ANALYTICAL STUDY ON THE EFFECT OF NANO-SILICA ADDITION IN ENHANCING DURABILITY CHARACTERISTICS OF CONCRETE

This research evaluates the sorptivity, water absorption, and acid resistance of M70 grade concrete with the incorporation of nano silica. The normal M70 concrete was prepared using 10% of silica fume and 11% of fly ash as partial substitutes for cement to act as a robust reference mix. For enhanced durability, nano silica was incorporated as an additional partial substitute. Concrete cubes were cast, water-cured for 28 days, and subjected to 5% sulfuric acid (H₂SO₄) and 5% hydrochloric acid (HCl) for 30 and 90 days to assess acid resistance. To check permeability and improvement in pore structure, water absorption and sorptivity tests were also conducted following established procedures. The results indicated that, when compared to the normal mix, microsilica concrete exhibited less degradation. The weight loss in nano silica concrete following exposure to acid for 90 days was 2.12% in HCl and 2.95% in H₂SO₄, whereas the normal mix lost 4.51% and 5.75% of their weights, respectively. For nano silica concrete, the residual compressive strength was 93% of the original strength, while the normal mix had 86%. The percentage of water absorption in nano silica concrete reduced from 2.45% for the normal mix to 1.65%. Even the capillary suction and permeability decreased significantly, as noted from the sorptivity reduced from 2.13 mm to 1.39 mm. Based on the conclusions drawn from the research, incorporation of nanosilica in M70 grade concrete reduces sorptivity, reduces water absorption, and enhances acid resistance all factors that contribute to the overall durability and service life of high-strength concrete.