Enhancing sustainability with ternary blended cement and fine aggregate in self-compacting lateritic concrete with supplementary materials

This study explores an innovative approach to sustainable self-compacting concrete (SCC) by partially replacing natural fine aggregate (NFA) with lateritic fine aggregate (LFA) and manufactured sand (M-sand). Additionally, fly ash and ultrafine ground granulated blast furnace slag (UGGBS) were introduced as supplementary cementitious materials to enhance performance. Fresh properties of the SCC mixes met as per Indian standards, demonstrating satisfactory flowability, passing ability, and stability. Among the mixes, the combination of 30 % fly ash (30 F), 30 % LFA (30 L) and 50 % M-sand (50 M) replaced in the conventional SCC mix, designated as C30F30L50M, exhibited optimal workability and segregation resistance. Mechanical tests revealed improvements in long-term strength, with the optimized mix containing 5 % UGGBS showing superior flexural strength at 90 days. Durability assessments indicated increased water absorption in mixes containing LFA and M-sand, while the control mix displayed better resistance to chloride penetration. Microstructural analyses (SEM, XRD, TGA/DTG, and FTIR) confirmed enhanced hydration and phase development influenced by the blend of fine aggregates and supplementary materials. The findings highlight the potential of utilizing LFA and M-sand in SCC to achieve sustainable concrete with improved performance characteristics. • Sustainable alternatives to natural river sand by using lateritic fine aggregate and M-sand in self-compacting concrete. • Fresh concrete mixes met the workability criteria outlined in code, with one blend showing notably stable and cohesive flow. • Long-term strength improved with the use of UGGBS, particularly in the mix combining 30 % LFA, 50 % M-sand, and 5 % UGGBS. • Water absorption increased with alternative aggregates; chloride resistance was highest in the control mix. • Microstructural tests showed ongoing hydration and phase refinement, supporting long-term performance of modified blends.