AH3 phase in the hydration product system of AFt-AFm-AH3 in calcium sulfoaluminate cements: A microstructural study. (10th April 2018)

• Record Type: Journal Article
• Authors: Zhang, Yangyang; Chang, Jun; Ji, Juan
• Is Part Of: Construction & building materials. Volume 167(2018)
• Page Start: 587
• Page End: 596
• Publication Date: 2018-04-10
• Subjects: AH3-C AH3 phase synthesized by chemical method -- AH3-H AH3 phase during the hydration of C4A3Š -- C CaO -- A Al2O3 -- F Fe2O3 -- Š SO3 -- H H2O; Calcium sulfoaluminate cement -- Hydration -- AH3 phase -- Rietveld methodology -- Crystallite size; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.02.052
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Microstructure of AH3 phase in both of the AFm-AH3 and AFt-AH3 systems was thoroughly characterized. AH3 -H phase in both of the AFm-AH3 and AFt-AH3 systems has a microcrystalline or nanocrystalline structure. Average crystal size of the AH3 -H phase in AFt-AH3 system is close to 20 nm. Ion activity product of the AH3 -H phase in the AFm-AH3 system is smaller than that in AFt-AH3 system. Abstract: In calcium sulfoaluminate cements, two hydration product systems, namely the monosulfate (AFm) – aluminum hydroxide (AH3 ) system and the ettringite (AFt) – AH3 system, were created based on the reactions of ye'elimite with and without gypsum. From chemically synthesized samples, the composition and microstructure of the AH3 phase in the hydration product system AFt-AFm-AH3 were characterized using X-ray diffraction, Rietveld method, thermogravimetric analysis, 27 Al magic angle spinning nuclear magnetic resonance spectroscopy, field emission scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. It was seen that AH3 phase in both AFm-AH3 system and AFt-AH3 system had a gibbsite-like structure presented in a microcrystalline or nanocrystalline structure, while the AH3 phase in the AFt-AH3 system had an average crystallite size close to 20 nm.