Impact of sample preparation on the specific surface area of synthetic ettringite. (August 2016)

• Record Type: Journal Article
• Authors: Mantellato, Sara; Palacios, Marta; Flatt, Robert J.
• Is Part Of: Cement and concrete research. Volume 86(2016)
• Page Start: 20
• Page End: 28
• Publication Date: 2016-08
• Subjects: Thermal treatment (A), -- Surface area (B), -- X-ray diffraction (B), -- Ettringite (D), -- Solvent exchange; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2016.04.005
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: The effect of sample preparation, including degassing conditions and method to stop cement hydration, on the specific surface area (SSABET ) of synthetic ettringite (AFt) was studied. Dehydration of AFt occurs even at moderate temperatures under N2 flow (0% RH). However, partial dehydration associated to a loss of up to 12 water molecules does not imply a change in SSABET . A mild degassing 16 h at 40 °C under N2 flow is suggested mainly to preserve the chemical composition and morphology of calcium sulfate carrier. At higher temperatures, ettringite dehydration involves a significant modification of its crystalline structure and increase of the SSABET . Typical protocols to stop cement hydration, solvent exchange and freeze-drying, lead to larger water removal from the AFt and crystallinity reduction, being significantly higher when the latter is applied. However, only freeze-drying leads to a moderate increase of the synthetic AFt SSABET .