A preliminary study of alkali-activated slag blended with silica fume under the effect of thermal loads and thermal shock cycles

The elevated temperature performance of alkali-activated ground granulated blast-furnace slag/silica fume (SF) at ratios of 100/0, 95/5, 90/10 and 85/15 wt.%, activated with sodium silicate is presented. The specimens were exposed to elevated temperatures ranging from 400 degrees C to 1000 degrees C with an increment of 200 degrees C. Compressive strengths before and after firing were measured. Water quenching test was applied to determine thermal shock resistance of various mixtures. The various decomposition phases formed were identified using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS). The results indicated that the compressive strengths before and after firing increased with the presence of SF up to 800 degrees C, then decreased at 1000 degrees C in comparison with neat activated slag specimens. The relative strength of the neat alkali-activated slag paste was superior and the inclusion of SF had adversely impact on the thermal shock resistance. 2012 Elsevier Ltd. All rights reserved.