Performance evaluation and TiGRA-based multi-response optimization of sustainable fly ash-slag-based one-part alkali-activated concrete mix design

The need for sustainable, practical alternatives to Portland cement and two-part alkali-activated systems has led to the development of one-part alkali-activated concrete (OPAAC), which efficiently reuses industrial by-products like fly ash and ground granulated blast furnace slag (GGBS). This study evaluates the fresh (workability) and hardened properties (compressive, tensile, and flexural strengths) of FA-GGBS-based OPAAC, along with durability indicators including sorptivity and chloride ion permeability. A performance-based multi-response optimization using a Taguchi L₉ array and Grey Relational Analysis (GRA) is adopted to optimize the binder ratio (FA: GGBS), water-to-binder ratio (w/b), and activator-to-binder ratio (A/b). SEM and XRD analyses indicate that the porous, N-A-S-H–dominated matrix observed in FA-rich mixes gradually evolves into a denser C-A-S-H/N-C-A-S-H gel network as the GGBS content increases, correlating with improved strength and durability. The optimal OPAAC mix, achieving an M40 grade concrete, is obtained at a 70:30 binder ratio, a water-to-binder ratio (w/b) of 0.35, and an activator-to-binder (A/b) ratio of 14%. This work directly supports global sustainability efforts by promoting low-carbon materials, resource efficiency, and environmentally responsible construction, aligning with SDGs 9, 11, 12 and 13.