Multi-objective Optimisation of One-Part Slag–Flyash–Microsilica Based Alkali-Activated Ternary Binder Mixes

Abstract The study reports the properties of slag–flyash–microsilica ternary blended one-part alkali-activated binder system. Microsilica, characterised by high surface area, helps in reducing porosity and also the presence of active silica contributes enhancing the reactivity of binders, while flyash and GGBS offer aluminosilicates to support alkali activation. Taguchi’s design of experiment, integrated with Taguchi grey relational analysis (GRA) is employed to determine the optimal precursor blends, water content and activator dosages to achieve setting times, flow characteristics and compressive strength comparable to conventional OPC. The optimised mix exhibited flowability of 120%, an IST of 46 min, FST of 95 min, and compressive strengths of 54.65 MPa and 69.75 MPa at 7 and 28 days, respectively. The predicted results of the proposed regression model were experimentally validated, with deviations not exceeding 5%. Furthermore, microstructural analyses were performed using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) to examine changes in morphology, mineral phases, and molecular bonding of the binder mixes, respectively. The microanalysis has confirmed formation of dense C/N-A-S-H resembling gels as product of alkali-activation.. Carbon footprint, eco-efficiency and cost analysis were performed and found that the optimised mix is an eco-friendly alternative to OPC-based binders. Graphical Abstract