Synergistic Effect of CNSA, Silica Fume, Metakaolin and Slag on Mechanical Properties of Concrete Mix

Synergistic Effect of CNSA, Silica Fume, Metakaolin and Slag on Mechanical Properties of Concrete Mix

Initially, cashew nutshell ash (CNSA) replaces cement in M25 grade concrete with a 0.5 water–cementitious materials ratio, yielding favorable results with a 15% CNSA mix. This study explores the synergistic effects of CNSA with other cementitious admixtures—silica fume (SF), ground granulated blast furnace slag (GGBS), and metakaolin (MK). In the second phase, each admixture individually replaces cement with optimal proportions determined: 10% for SF, 20% for MK, and 50% for GGBS. The third stage combines these admixtures in various ratios (SF-MK, SF-GGBS, MK-GGBS, SF-MK-GGBS), which are then mixed with the previously established optimum CNSA dose (15% CNSA). The most effective blend, in terms of strength and performance, is identified as 15CNSA+10SF. All combinations undergo testing for mechanical properties, and the final stage mixes are subject to Energy Dispersive X-Ray (EDAX) and SEM analyses.