Carbonation-induced mineralogical changes in coal mining waste blended cement pastes and their influence on mechanical and microporosity properties
Publisher
MDPIDate
2018-04-01Citation
10.3390/min8040169
Minerals 8.4 (2018): 169
ISSN
2075-163XDOI
10.3390/min8040169Funded by
This research was funded by the Spanish Ministry of Economy and Competitiveness (Project Refs. MAT2012-37005-CO3-01/02/03) and MINECO/FEDER (BIA2015-65558-C3-1/2/3-R). The authors wish to thank the Sociedad Anónima Hullera Vasco-Leonesa (León, Spain), Sika (Madrid, Spain) and the Spanish Cement Institute (IECA) for their support in this researchProject
Gobierno de España. MAT2012-37005-CO3-01/02/03; Gobierno de España. BIA2015-65558-C3-1/2/3-REditor's Version
https://doi.org/10.3390/min8040169Subjects
Accelerated carbonation; Blended cements; Coal mining waste; Mineralogy; Properties; GeologíaRights
© 2018 by the authors. Licensee MDPI, Basel, SwitzerlandAbstract
The worldwide pursuit of new eco-efficient pozzolans is ongoing. Kaolinite-based waste is an eco-friendly source of recycled metakaolinite, a highly pozzolanic product. In this study, a blended cement paste containing 20% activated coal waste (ACW) was exposed to a 100% CO2atmosphere at 65% RH for 7 days. The variations in its phase composition and strength were studied and compared to an OPC control. Both pastes were cured for 28 days prior to the carbonation test. Reaction kinetics were assessed using XRD, SEM/EDX, TG/DTG, FT-IR, Micro-Raman spectroscopy, pore solution pH and the cumulative carbonated fraction. The blended cement carbonated 68% faster than the control. While portlandite carbonation was the main reaction in both cements, decalcification was also observed (more intensely in the 20% ACW paste) in other hydraulic calcium phases (C-S-H gel, monocarboaluminate (C4AcH12), ettringite and tetracalcium aluminate (C4AH13). The end product of this reaction was calcium carbonate, mainly in the form of calcite, although traces of aragonite and amorphous carbonate were also detected. Compressive strength values rose with accelerated carbonation time and pore size reduction in both cement pastes.
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Google Scholar:Frías, Moisés
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Vigil de la Villa Mencía, Raquel
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García, Rosario
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Rodríguez, Olga
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Fernández-Carrasco, Lucía
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Martínez-Ramírez, Sagrario
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