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Recycling 2016, 1(2), 232-241; doi:10.3390/recycling1020232

Coal Mining Waste as a Future Eco-Efficient Supplementary Cementing Material: Scientific Aspects

1
Eduardo Torroja Institute for Construction Sciences (IETcc-CSIC), Madrid 28033, Spain
2
CSIC-UAM Associated Unit, Department of Geology and Geochemistry, Autonomous University of Madrid, Madrid 28049, Spain
3
Institute for the Structure of Matter (IEM-CSIC), Madrid 28006, Spain
*
Author to whom correspondence should be addressed.
Academic Editors: Michele Rosano, Katerina Adam and Maria Menegaki
Received: 20 May 2016 / Revised: 4 July 2016 / Accepted: 5 July 2016 / Published: 16 July 2016
(This article belongs to the Special Issue Mining Waste Management and Resource Recovery)
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Abstract

The stockpiling of tailings around coal mines poses a major environmental problem. Nonetheless, this clay mineral (kaolinite)-based waste can be reused as a supplementary cementitious material (recycled metakaolinite) in the manufacture of future eco-efficient cements. This paper explores the most significant scientific questions posed in connection with the conversion of this waste into pozzolans, such as the variation in product mineralogy depending on the sintering temperature and its effect on reaction kinetics in the pozzolan/Ca(OH)2 system over a period of 365 days. The findings show that the optimal sintering temperature is 600 °C, such that the cementitious properties of the activated product are determined solely by the conversion of kaolinite into metakaolinite and are unaffected by the other clay minerals (micas). The presence of 20% activated coal waste favors the formation of larger amounts of aluminous phases such as C4AH13 and C4AcH12 than in the reference paste and enhances C–S–H gel polymerization. View Full-Text
Keywords: coal mining waste; mineralogy; blended cements; hydrated phases coal mining waste; mineralogy; blended cements; hydrated phases
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Frías, M.; García, R.; Vigil de la Villa, R.; Martínez-Ramírez, S. Coal Mining Waste as a Future Eco-Efficient Supplementary Cementing Material: Scientific Aspects. Recycling 2016, 1, 232-241.

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