An exploratory study on alkali-activated slag blended with quartz powder under the effect of thermal cyclic loads and thermal shock cycles

Ground granulated blast-furnace slag (slag) in alkali-activated slag (AAS) paste was partially replaced with quartz powder (QP) at levels ranging from 0% to 30% with an increment of 5%, by weight. Workability and compressive strength of different mixtures were measured. After 28 curing days, some specimens were exposed to 7, 14, 21 and 28 heating/cooling (H/C) cycles. To complete one cycle, the temperature was kept constant at either 200 °C or 400 °C for 6 h, followed by 18 h cooling. Compressive strength after each cyclic regime was measured. Other specimens were exposed to rapid temperature changes to determine their thermal shock resistance. The various decomposition phases formed and the morphology of formed hydrates were identified using X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS). The results showed an increase in the workability with the inclusion of QP. A reduction in the compressive strength after exposure to H/C cycles was observed. This reduction increased as the heating peak temperature and H/C cycles increased. As QP content increased as the improvement in the compressive strength before and after H/C cycles increased. In addition, high QP content increased the thermal shock resistance.