Utilization of carbide slag-granulated blast furnace slag system by wet grinding as low carbon cementitious materials

Abstract

Alkali-activated slag with lower carbon emission exhibits a great potential as an alternative for Portland cement. The activity of slag and the base used decide the basic performances of this kind of material. In this study, granulated blast-furnace slag was treated by wet grinding to promote its reactivity (i.e. WGGBS), and carbide slag (CS), one kind of industrial wastes, was used as the alkali. CS activating WGGBS system was designed, where the replacement ratio of WGGBS by CS was less than 10%. Mechanical property of this system was examined and the hydration mechanism was investigated by hydration heat, XRD, TG, NMR, and SEM. Results showed that CS could significantly increase the compressive strength of WGGBS mortar as well as promote its hydration to facilitate the formation of C-S-H gel, hydrotalcite, and hemicarbonate. Moreover, via wet grinding process, D50 of CS was reduced from 15.90 μm of raw CS (RCS) to 2.40 μm, thereby wet grinded CS (WGCS) could further increase the compressive strength of WGGBS mortar, in comparison with RCS, especially for the early age, because the finer particle was easier to dissolve into liquid phase to participate in the hydration. Such results suggested one novel method to promote the activity of solid waste and also offered useful experience for the design of GGBS-based low carbon cementitious materials.