Influence of ZnO on the activation of kaolinite-based coal waste: Pozzolanic activity and mineralogy in the pozzolan/lime system
Entity
UAM. Departamento de Geología y GeoquímicaPublisher
Elsevier B.V.Date
2018-02-14Citation
10.1016/j.clay.2018.02.007
Applied Clay Science 156 (2018): 202-212
ISSN
0169-1317 (print); 1872-9053 (online)DOI
10.1016/j.clay.2018.02.007Funded by
The authors wish to express their gratitude and sincere appreciation to the Spanish Ministry of the Economy and Competitiveness under coordinated projects MAT2012-37005-CO3-01, BIA2015-65558-C3-1-2-3R (MINECO/FEDER) for financing this research work and grateful to the Sociedad Anónima Hullera Vasco-Leonesa (Spain) and to the Spanish Cement Institute (IECA) for their assistance with this researchProject
Gobierno de España. MAT2012-37005-CO3-01; Gobierno de España. BIA2015-65558-C3-1-2-3REditor's Version
https://doi.org/10.1016/j.clay.2018.02.007Subjects
Coal waste; Cement; Thermal and chemical activation; Hydrated phases; Stratlingite; LDH; Amorphous materials; C-S-H gels; GeologíaRights
© 2018 Elsevier B.V.Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Abstract
One inconvenience presented by the thermal activation of kaolinite-based wastes is their low content of metakaolinite, a highly pozzolanic product listed in current standards for the manufacture of commercial cements. The addition of a chemical activator during the thermal activation process is a priority line of research to increase the reactivity of the recycled metakaolinite. In this paper, an additional chemical activator, ZnO, is studied and its effect on both pozzolanic properties and the evolution of mineralogical phases in the thermal activation of coal waste with a reaction time of up to 90 days in the pozzolan/lime system. To do so, activation temperatures of between 550 °C/650 °C were selected and additions of chemical activator (ZnO) in percentages of between 0.0% and 3.0% by weight of coal waste, because it is an activator with a positive effect on a 100% natural kaolinite. The results showed that the incorporation of ZnO inhibited the reactivity of the recycled metakaolinite and in consequence, the capacity of the metakaolinite to react with the surrounding lime; even more so when the content of added chemical activator was raised, albeit with some exceptions, in the samples activated at 550 °C and 650 °C with 0.5% of chemical activator. In none of the cases under analysis was the chemical activator able to improve the properties of the metakaolinite in comparison with the properties of the reference sample activated only with temperature. The hydrated phases that appeared in the pozzolanic reaction were tetracalcium aluminate hydrate, stratlingite, monosulfoaluminate hydrate and LDH (phyllosilicate/carbonate)
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Google Scholar:García Giménez, Rosario
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Vigil de la Villa Mencía, Raquel
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Martínez-Ramírez, Sagrario
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Fernández-Carrasco, L.
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Frías, M.
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