Effect of replacement of fly ash with silica fume in mineral admixture based self-compacting concrete

Abstract

The present study investigates the influence of partially replacing fly ash with silica fume in mineral admixture–based self-compacting concrete on its mechanical properties. Fly ash is widely used in concrete for its pozzolanic activity and sustainability benefits, while silica fume, with its ultra-fine particle size and high silica content, is known to enhance strength and impermeability. In this work, concrete mixes were prepared with a fixed total mineral admixture content, where varying proportions of fly ash were substituted with silica fume. Compressive strength, split tensile strength, and flexural strength tests were conducted at different curing ages. The results demonstrated that partial replacement of fly ash with silica fume significantly improved early-age strength. The study highlights the potential of an optimized fly ash–silica fume combination for producing high-performance and durable concrete while promoting the sustainable use of industrial by-products.