Developing an indexing methodology for estimating the reactivity of slag from different sources use in alkali-activated materials

The slag is rich in reactive aluminosilicate components and can be combined with alkali solution to form a three-dimensional binder. However, the inherently heterogeneous nature of slag presents challenges to the standardization of alkali-activated product. The fundamental objective of this work is to understand differences of characteristics between slags obtained from different sources within China, including physical properties, chemical composition, microstructure, elemental distribution, mineral phases, chemical bonding, glass contents, together with the microstructures of glassy phase. A novel reactivity index concept to evaluate slag used in alkali activated materials was proposed using seven typical slags in China and validated it against nine data from literature, confirming its considerable effectiveness and usefulness in reactivity evaluations. The positive correlations were found between the reactivity index of slag and the strengths of alkaline-activated pastes prepared by different methods and this index optimizes the process of raw waste selection.