The deterioration and environmental impact of binary cements containing thermally activated coal mining waste due to calcium leaching
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2018-05-10
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Abstract
Calcium-leaching processes can potentially degrade the structure of a concrete matrix. This problem is studied here through the progressive dissolution of Ca2+ in both ordinary Portland cement pastes (C-0) and binary cement blends (C-20) containing 20% thermally Activated Coal Mining Waste (ACMW).1 A series of accelerated tests are conducted that involve the immersion of these cement pastes in a 6 M ammonium nitrate solution at a temperature of 20 C for 7 and for 21 days. A rise in paste porosity was observed, due to increased capillary pore sizes of between 5 and 0.1 μm. In the case of the 20% ACMW pastes (C-20), calcium leaching decreased, probably as a consequence of the pozzolanic effect of the ACMW, while potassium and magnesium leaching increased, due to the presence of the phyllosilicates in the ACMW. The paste compounds most affected by leaching were Ca(OH)2, C6AS3H32, and C4AC¯H12. In general terms, it can be concluded that the incorporation of ACMW into binary cements slightly reduces the calcium leaching phenomena. Concerning the environmental impact assessment, the substitution of 20% OPC by ACMW reduced CO2 emissions by as much as 12% and improved energy efficiency by using approximately 19% fewer fossil resources.
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Publisher Copyright: © 2018
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ACMW , Calcium leaching , Thermally activated coal mining waste , Binary cements , Degradation , ACMW , Calcium leaching , Thermally activated coal mining waste , Binary cements , Degradation , Renewable Energy, Sustainability and the Environment , Building and Construction , General Environmental Science , Strategy and Management , Industrial and Manufacturing Engineering , SDG 7 - Affordable and Clean Energy , SDG 13 - Climate Action , Funding Info , This research was developed in the framework of the MATCON Associated Unit (CSICTecnalia,_x000D_ Madrid, Spain) with the support of the Spanish Ministry of Economy and_x000D_ Competitiveness (Project Ref. MAT2012-37005-CO3-01/02/03) and the European_x000D_ Regional Development Fund (MINECO/FEDER) (Project Ref.BIA2015-65558-C3-_x000D_ 1,2,3-R. The authors are also grateful to the Sociedad Anónima Hullera Vasco-Leonesa_x000D_ and to the Spanish Cement Institute (IECA) for providing us with raw materials. , This research was developed in the framework of the MATCON Associated Unit (CSICTecnalia,_x000D_ Madrid, Spain) with the support of the Spanish Ministry of Economy and_x000D_ Competitiveness (Project Ref. MAT2012-37005-CO3-01/02/03) and the European_x000D_ Regional Development Fund (MINECO/FEDER) (Project Ref.BIA2015-65558-C3-_x000D_ 1,2,3-R. The authors are also grateful to the Sociedad Anónima Hullera Vasco-Leonesa_x000D_ and to the Spanish Cement Institute (IECA) for providing us with raw materials.
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Arribas , I , Vegas , I , García , V , Vigil de la Villa , R , Martínez-Ramírez , S & Frías , M 2018 , ' The deterioration and environmental impact of binary cements containing thermally activated coal mining waste due to calcium leaching ' , Journal of Cleaner Production , vol. 183 , pp. 887-897 . https://doi.org/10.1016/j.jclepro.2018.02.127