RSM based optimization and environmental impact assessment of a ternary blended one part alkali activated binder with enhanced mechanical performance

The performance of AABs is governed by a complex interplay of variables such as binder content, activator dosage, and supplementary materials. Therefore, systematic optimisation is essential to develop mixes that offer both high performance and environmental benefits. The performance of ternary one-part alkali-activated binders incorporating Class F fly ash, GGBS, and silica fume was evaluated and optimised using Box–Behnken–based response surface methodology. BBD was utilised to evaluate and fine-tune the effects of critical parameters such as the binder ratio, solid activator dosage, and silica fume content on compressive strength. Most of the trial mixes achieved strengths exceeding 40 MPa due to the synergistic effect of high GGBS content (30–35%), silica fume (5–10%), and an optimal alkali activator dosage. Among the evaluated mixes, 7.5% silica fume was found to provide the most balanced performance in terms of flowability, consistency, and setting behaviour. The optimised mix achieved compressive strengths of 47 MPa at 7 days and 54 MPa at 28 days, demonstrating its potential for structural elements, repair or retrofitting applications where compressive strength above 50 MPa is required. BBD was employed to model and optimise compressive strength. The developed quadratic model was statistically significant (p = 0.037; R² = 90.91%) with insignificant lack-of-fit (p > 0.05). The experimental validation showed good agreement between predicted and measured values, with errors below 10%, confirming the reliability of interpolation within the investigated domain.