Abstract
In this study, the possibility of using quartz powder (QP) to improve the workability as well as the compressive strength of alkali-activated metakaolin (AAMK) paste before and after exposure to elevated temperatures has been investigated. Metakaolin (MK) was partially replaced with QP at levels ranging from 0% to 30% with an increment of 5%, by weight. After curing, specimens were exposed to different elevated temperatures ranging from 400°C to 1000°C with an interval of 200°C for 2h. Weight and compressive strength of specimens before and after being exposed to different elevated temperatures were thoroughly explored. The various decomposition phases formed upon exposure to temperatures were identified using X-ray diffraction (XRD)-phase characterizations and thermogravimetric (TGA)-thermal characterizations. The microstructure of the formed hydration products was determined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the workability as well as compressive strength before and after being exposed to elevated temperatures increased with increasing QP content. The geopolymer formulations developed in this study appeared as promising candidates for high-temperature applications refractory and fire resistant.
•Flowability increased as the content of QP in AAMK increased.•The inclusion of QP in AAMK paste increased the compressive strength.•The residual compressive strength of AAMK increased with the inclusion of QP.•The residual strength for all mixtures increased rapidly at 400°C.•Beyond 400°C, the residual compressive strength decreased gradually.