Effect of thermal treatment on reactivity and mechanical properties of alkali activated shale–slag binder

Abstract

This paper is aimed at investigating the properties of calcined shale–slag as an alternative alkali-activated constructional binder hardened by geopolymerization reaction with sodium silicate solution. Focus is put on possibilities of thermal treatment in temperature range of 500–1000°C and investigation of structural changes. These investigations were done by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FTIR), measurement of specific surface area, pozzolanic activity and mechanical strength of prepared geopolymer mixtures. Reaction rates were measured by small amplitude dynamic rheometry as a relatively new method for investigation of geopolymerization process. The best compression strength of 82.52MPa and highest reactivity, according to the pozzolanic activity and dynamic rheometry, was achieved by thermal treatment at 600°C for duration of 4h.