Experimental Investigation on M30 Grade Concrete Incorporating Fly Ash and Nano Silica

The growing demand for sustainable construction materials has led to increased interest in the utilization of industrial by- products and nano-materials in concrete. This study presents an experimental investigation on the mechanical and durability performance of M30 grade concrete incorporating fly ash and nano silica as partial replacements of cement. Fly ash was used at a constant replacement level of 10%, while nano silica was varied at 1%, 2%, and 3% by weight of cement. Fresh concrete properties were evaluated using slump cone test. Hardened concrete properties were assessed through compressive strength, split tensile strength, and flexural strength tests at 7, 14, 28, and 56 days. Durability characteristics were examined using water absorption and sorptivity tests. The results indicate that the incorporation of fly ash and nano silica significantly enhances both strength and durability characteristics of concrete. The mix containing 10% fly ash and 2% nano silica exhibited the highest compressive strength of 44.5 MPa and 48.6 MPa at 28 and 56 days respectively, representing an increase of about 15–18% compared to control concrete. Durability results showed reduced water absorption and sorptivity, indicating improved resistance to moisture ingress. The study concludes that the combined use of fly ash and nano silica produces a synergistic effect and can be effectively used to develop sustainable and high-performance structural concrete.