AH_3 phase in the hydration product system of AFt-AFm-AH_3 in calcium sulfoaluminate cements: A microstructural study

摘要

In calcium sulfoaluminate cements, two hydration product systems, namely the monosulfate (AFm) - aluminum hydroxide (AH(3)) system and the ettringite (AFt) - AH(3) system, were created based on the reactions of ye'elimite with and without gypsum. From chemically synthesized samples, the composition and microstructure of the AH(3) phase in the hydration product system AFt-AFm-AH(3) were characterized using X-ray diffraction, Rietveld method, thermogravimetric analysis, Al-27 magic angle spinning nuclear magnetic resonance spectroscopy, field emission scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. It was seen that AH(3) phase in both AFm-AH(3) system and AFt-AH(3) system had a gibbsite-like structure presented in a microcrystalline or nanocrystalline structure, while the AH(3) phase in the AFt-AH(3) system had an average crystallite size close to 20 nm. (C) 2018 Elsevier Ltd. All rights reserved.