Use of Isothermal and Isoperibolic Calorimetry to Study the Effect of Zinc on Hydration of Cement Blended with Fly Ash

Autor:	Pavel Šiler, Iva Kolářová, Radoslav Novotný, Jiří Másilko, Jan Bednárek, Martin Janča, Jan Koplík, Jan Hajzler, Lukáš Matějka, Michal Marko, Jiří Švec, Martin Zlámal, Eva Kuzielová, Tomáš Opravil, František Šoukal
Jazyk:	angličtina
Rok vydání:	2020
Předmět:	portland cement zinc isothermal calorimetry isoperibolic calorimetry fly ash Technology Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85
Zdroj:	Materials, Vol 13, Iss 22, p 5215 (2020)
Druh dokumentu:	article
ISSN:	1996-1944
DOI:	10.3390/ma13225215
Popis:	Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. Zinc is one of these elements. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO3)2 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05%, 0.1%, 0.5% and 1% of cement weight. The effect of zinc on hydration was monitored by isothermal and isoperibolic calorimetry. A 15% addition of fly ash to cement mainly causes further retardation of hydration reactions due to the reactions of fly ash particles with Ca2+ ions from cement. The strongest effect on the hydration retardation from all investigated compounds showed in ZnO as it dissolves very slowly. On the contrary, for the dosage of 1% of zinc in the form of ZnCl2 significant acceleration of hydration occurred. In this work, a synergistic effect on the prolongation of hydration with a combination of cement, zinc and fly ash was demonstrated. The lengths of induction periods were assessed from detected calorimetric curves and from these lengths the curves were gained by fitting with the exponential function. Final products were next analyzed using X-ray diffraction.
Databáze:	Directory of Open Access Journals
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