Topic
Ettringite
About: Ettringite is a research topic. Over the lifetime, 2702 publications have been published within this topic receiving 67056 citations. The topic is also known as: woodfordite.
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TL;DR: In this paper, the impact of sulfate and alkali on the hydration kinetics and microstructural development of alite was investigated and the results showed that the highest mechanical strength obtained with the combination of alkalis and sulfate is not dependent on the morphology of hydrates.
137 citations
TL;DR: In this paper, an empirical approach to the problem has been offered, based on the empirical data of the C 4 AH 13 -monosulphate solid solution series, and experimental data of CSH compositions in alkali solutions indicate that CSH in cement porewater solutions should have a Ca/Si ratio of around 1.1, much lower than values usually reported from SEM measurements on actual pastes.
137 citations
TL;DR: In this paper, the authors studied hydration stages and phase transformation mechanism of fresh calcium sulfoaluminate (CSA) cement and found that Ettringite (AFt) and monosulfate (AFm) are metastable phases and have poor crystallization degree at early-age hydration.
137 citations
TL;DR: The results showed that it is feasible to use red mud and coal gangue to replace up to 50% of the raw materials to produce cementitious material, which can be called as silica-alumina based cementitiousmaterial.
135 citations
Katholieke Universiteit Leuven1, Ghent University2, Indian Institute of Technology Madras3, École Polytechnique Fédérale de Lausanne4, RWTH Aachen University5, University of Toronto6, Institut national des sciences appliquées de Toulouse7, Swiss Federal Laboratories for Materials Science and Technology8
TL;DR: In this paper, a round-robin test on the impact of hydration stoppage methods on the composition of hydrated cements was conducted and a regular and a fly ash blended Portland cement hydrated for 90 days were selected.
Abstract: For many microstructural studies it is necessary to “stop” cement hydration—to remove free water. This paper describes the results of a round robin test on the impact of hydration stoppage methods on the composition of hydrated cements. A regular and a fly ash blended Portland cement hydrated for 90 days were selected. Ten laboratories participated in the round robin test. Four common hydration stoppage methods were studied: (1) oven drying at 105 °C, (2) solvent exchange by isopropanol, (3) vacuum drying and (4) freeze drying. After the stoppage of hydration powder samples were studied by thermogravimetry (TG) and X-ray diffraction (XRD). Bound water and Ca(OH)2 content were determined based on the TG data. Portlandite and ettringite content were quantified by Rietveld analysis of the XRD data. The goal was to establish interlaboratory reproducibility and to identify the best available protocols for research and standardization purposes. Based on the results of the round robin test three recommendations are made. (1) Oven drying at 105 °C is not recommended. This dehydrates, alters and decomposes calcium aluminate hydrates significantly more than other methods and often produced carbonation artefacts. (2) Isopropanol exchange is the most appropriate hydration stoppage method for the study of the complete hydrate assemblage of cements, including calcium aluminate hydrates such as ettringite and AFm phases. (3) For quantification of portlandite (Ca(OH)2) all tested hydration stoppage protocols are satisfactory, with the exception of oven drying.
135 citations