Behavior of Alkali-Activated Metakaolin Pastes Blended with Quartz Powder Exposed to Seawater Attack

The purpose of this work is to investigate the resistance of alkali-activated metakaolin (AAMK) paste specimens blended with different amounts of quartz powder (QP) against different environmental conditions. Metakaolin (MK) was partially substituted with QP at levels of 10, 20, 30, and 40%, by weight. After initial curing, specimens were exposed to different conditions including air, potable fresh water, and seawater up to 12 months. Compressive strength before exposure as well as strength deterioration ratio (SDR) after exposure were determined. The mineralogical compositions for selected mixtures before and after exposure to seawater attack were identified by X-ray diffraction (XRD) and thermogravimetric analysis (TGA) and compared with those cured in lab air. The microstructure and morphology were identified using scanning electron microscopy (SEM). The results showed that the incorporation of QP in MK-based geopolymers seemed as promising candidates for marine structure applications. (C) 2018 American Society of Civil Engineers.