Influence of novel activation techniques on mechanical and microstructural characteristics of alkali activated one-part binder

Portland cement production contributes over 7 % of global greenhouse gas emissions, driving the search for sustainable alternatives. Although alkali-activated materials (AAMs) and geopolymers offer promising low-carbon solutions, conventional two-part activator systems pose handling and transportation challenges for in situ construction due to alkali solutions' viscous and hazardous nature. The present study develops novel one-part alkali-activated binders (AAB) employing uncoupled (UMC) and coupled (CMC) mechano-chemical activation techniques and investigates the effects of these activation methods on the compressive strength of AABs. In the present work, fly ash (FA) and ground granulated blast-furnace slag (GGBFS) were utilised as precursors, whereas sodium silicate (NS), sodium hydroxide (NH), and a mixed NS-NH are used as activators. Results indicate that UMC enhances strength by 20–25 %, while CMC results in an additional 20–40 % improvement. Mixed activators are enhancing the strength by 1.25–2.50 times. Microstructural analysis reveals that mixed activator-based binders exhibit denser structures with increased gel formation and reduced voids. On the other hand, mineralogical analysis confirms that the formation of high Si/Al ratio gels improved compressive strength for the binder made with a mixed activator. These findings demonstrate that one-part AABs with advanced activation techniques offer a viable, eco-friendly solution for waste utilisation and carbon footprint reduction in construction materials.