Developing FA-based cementless binder composite by opting sustainable technology: Application of brick and paving block

Cementless binders are made possible by the invention of geopolymers, which utilize alkaline activators to activate alumina-silicate materials. Alkaline activators, however, are corrosive and hazardous. Its minimal usage combined with advanced technology can make it sustainable. Therefore, this work was designed to develop alkali-activated binders (AABs) through mechano-chemical activation. Initially, three types of fly ashes (FAs) were activated, and their performance was evaluated using the strength activity index. The best-performing FA was used in the second group of experiments. Slag was coupled with FA, and dune sand (DS) was coupled in the third group. The physico-mechanical performance of each group was evaluated and the geopolymerization mechanism was assessed through FTIR analysis. By using DS, it was observed that the compressive strength has been significantly enhanced with an increase of 100 % compared to the FA-based binder, while the bulk density of both cases is almost the same (i.e., 1,650 kg/m3). Based on the multi-criteria analysis for three scenarios, it is revealed that the key performances of the high strength and durability, the lightweight and insulation, and the strength requirement are optimized by alkali-activated binders of FA + DS, FA-3, and FA + GGBS (Slag), respectively.