Mechanical properties and mechanisms of alkali-activated slag cementitious material with nanosilica at different temperatures

Nanosilica (NS) can significantly improve the mechanical properties and high-temperature resistance of ordinary concrete, so it is possible that NS could also enhance the high-temperature resistance of alkali-activated slag cementitious material (AASCM). Therefore, in this study, the effect of NS on the high-temperature resistance of AASCM was investigated. The mass loss, compressive strength and flexural strength of different AASCM mixes were determined, and scanning electron microscopy and X-ray diffraction were also performed. The findings indicate that adding NS is an efficient method for reducing the percentage mass loss of AASCM and improving its compressive and flexural strengths after high-temperature exposure. The results indicate an optimum NS content of 2%. Equations for the percentage mass loss, compressive strength and flexural strength of AASCM after high-temperature exposure considering the effect of the water/binder ratio and NS content were established. The results of this study will contribute to furthering applications of AASCM in construction engineering.