Utilization of optimized microwave sintering to produce safe and sustainable one-part alkali-activated materials

Sodium hydroxide (NaOH) as an alkaline activator presents a vital limitation in the mass production of alkali-activated binders due to its severe effect on users' safety. In this study, safe and sustainable one-part alkali-activated slag mixes (OP-AAS) were prepared through an efficient microwave sintering for a mixture of active amorphous ground granulated blast furnace slag (GGBFS) and sodium hydroxide powder (NaOH). Different microwave-sintered powders were prepared using microwave energy of power 900 W for the mixture at different treatment periods (10, 20, and 30 min). Fresh and hardened properties of different OP-AAS mixes were studied. Moreover, the phase composition and microstructure were investigated using X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). Cytotoxicity/viability testing was performed to evaluate the cell death induced by the developed materials to measure their safety for the user. According to compressive strength, cytotoxicity/viability analysis, environmental impact and cost calculation of developed OP-AAS, it is concluded that employing microwave sintering for a short duration is sufficient to produce safe binding materials with adequate mechanical properties suitable for commercial applications in the construction sector.