Behaviour of calcium sulfoaluminate cement in presence of high concentrations of chromium salts |
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| Authors: | C.A. Luz M. Cheriaf |
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| Affiliation: | a Universidade Federal de Santa Catarina, Departamento Engenharia Civil, Campus Trindade 88040-900 Florianópolis (SC), Brazil
b Unité de Recherche en Génie Civil, Institut National des Sciences Appliquées de Lyon, Domaine Scientifique de la Doua, Bâtiment J. Tuset, 12 Avenue des Arts, 69 621 Villeurbanne Cedex, France |
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| Abstract: | This paper deals with the behaviour of calcium sulfoaluminate cement hydrated in presence of high concentration of soluble chromium salts (65 g/kg): chromium nitrate and sodium chromate. Chromium nitrate was chosen to verify the good retention of Cr3+ by calcium sulfoaluminate cement. Sodium chromate was employed to assess the ability of calcium sulfoaluminate to immobilize Cr6+.Leaching tests were carried out on two types of calcium sulfoaluminate cement containing 20% and 30% phosphogypsum, respectively. The microstructure was also investigated at 28 and 90 days.The results obtained point two main findings: - -
- the retention of Cr3+ is excellent (> 99%), regardless of the type of cement,
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- the retention of Cr6+ depends on the type of cement and, in this case, the U phase is detected and promotes some expansion leading to cracking of the matrix.
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| Keywords: | Calcium sulfoaluminate cement Ettringite U phase Leaching Stabilization |
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