Evolution of iron speciation during hydration of C{sub 4}AF

Journal Article · Sat Jul 01 00:00:00 EDT 2006 · Waste Management

DOI:https://doi.org/10.1016/j.wasman.2006.01.021· OSTI ID:20877586

Rose, J ^[1]; Benard, A ^[2]; El Mrabet, S ^[3]; Masion, A ^[3]; Moulin, I ^[4]; Briois, V ^[5]; Olivi, L ^[6]; Bottero, J -Y ^[3]

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1. CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France) and ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France)
2. ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France)
3. CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France)
4. LERM, 10, rue Mercoeur, 75011 Paris (France)
5. LURE Laboratoire pour l'Utilisation du Rayonnement Electromagnetique, Universite Paris-Sud, Orsay, France European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France)
6. ELETTRA Sincrotrone Trieste S.c.p.A. S. S. 14, Km. 163.5 in AREA Science Park, I-34012 Basovizza, TS (Italy)

It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C{sub 4}AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C{sub 4}AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C{sub 4}AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C{sub 4}AF forms C{sub 3}AH{sub 6} (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C{sub 3}AH{sub 6}; iron does not seem to be incorporated in the AFm structure.

• OSTI ID: 20877586
• Journal Information: Waste Management, Vol. 26, Issue 7; Conference: International workshop on mechanisms and modeling of waste/cement interactions, Meiringen (Switzerland), 8-12 May 2005; Other Information: DOI: 10.1016/j.wasman.2006.01.021; PII: S0956-053X(06)00046-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ALUMINATES
ATOMIC FORCE MICROSCOPY
CALCIUM
CALCIUM SILICATES
CEMENTS
HEAVY METALS
HYDRATION
IRON
ISOTHERMS
SEDIMENTS
SEMIMETALS
SOILS
SORPTION
SYNCHROTRON RADIATION
X-RAY SPECTROSCOPY