Performance and Microstructural Evolution of One-Part Alkali-Activated Cement in Tailings Stabilization

Abstract

This paper explores the role of one-part alkali-activated cement, utilizing metakaolin as a precursor, in the long-term stabilization of mining tailings. Investigating three key factors (Si/Al and Na/Si ratios and curing period), this study reveals insights into the mechanical performance and microstructure of alkali-activated cemented iron ore tailings. Unconfined compressive strength test, statistical analysis, and Scanning Electron Microscopy analysis with Energy Dispersive Spectroscopy were performed. Findings indicate that the Si/Al ratio significantly influences strength, with an optimal ratio of 3.5. The Na/Si ratio introduces complexity, affecting alkali availability and reactivity, leading to nuanced strength variations. Extended curing periods consistently enhance the strength of alkali-activated cement, highlighting its dynamic nature. Notably, the 7-day specimens exhibit a less homogeneous distribution, weaker bonding, and decreased structural integrity compared to their 60-day counterparts. This research underscores the intricate nature of alkali-activated cement hydration, emphasizing the interdependence of Si/Al and Na/Si ratios. The observed strengthening effect with prolonged curing suggests the potential for tailoring these materials to specific applications. Addressing a research gap, especially in applying alkali-activation to mining tailings stabilization, this study highlights metakaolin’s role as a suitable precursor.