Published March 2011 | Version v1
Journal article

Iron in carbonate containing AFm phases

  • 1. Empa, Laboratory for Concrete and Construction Chemistry, Uberlandstrasse 129, CH-8600 Duebendorf (Switzerland)
  • 2. CNRS, UMR 6002, LMI, F-63177 Aubiere (France)
  • 3. Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France)
  • 4. Swiss-Norwegian Beam Lines at ESRF, 6 rue Jules Horowitz, BP 220, 38043 Grenoble (France)
  • 5. Paul Scherrer Institute, Nuclear Energy and Safety Research Department, Laboratory for Waste Management, 5232 Villigen PSI (Switzerland)

Description

One of the AFm phases in hydrated Portland cement is Ca3(AlxFe2-x)O6.CaCO3.nH2O. It is based on hexagonal and platey structural elements and the interlayer structure incorporates CO32-. The solid phases were experimentally synthesized and characterized by different techniques including X-ray techniques (XRD and EXAFS) and vibrational spectroscopy techniques (IR, Raman). Fe-monocarbonate (Fe-Mc) and Al-monocarbonate (Al-Mc) were found to be stable up to 50 oC, while Fe-hemicarbonate (Fe-Hc) was unstable with respect to Fe-Mc in the presence of calcite. Fe-Mc has a rhombohedral R3-barc symmetry which is different from the triclinic of the Al analogue. Both XRD and thermodynamic modelling of the liquid compositions indicated that Al-Mc and the Fe-Mc phases do not form solid solution. The solubility products were calculated experimentally at 20 oC and 50 oC. Under standards condition the solubility products and other thermodynamic parameters were estimated using temperature-solubility product extrapolation and found to be logKS0 (Fe-Mc) = -34.59 ± 0.50, logKS0 (Fe-Hc) = -30.83 ± 0.50 and logKS0(Al-Mc) = -31.32 ± 0.50.

Availability note (English)

Available from http://dx.doi.org/10.1016/j.cemconres.2010.11.017

Additional details

Identifiers

DOI
10.1016/j.cemconres.2010.11.017;
PII
S0008-8846(10)00260-7;

Publishing Information

Journal Title
Cement and Concrete Research
Journal Volume
41
Journal Issue
3
Journal Page Range
p. 311-323
ISSN
0008-8846
CODEN
CCNRAI

Optional Information

Copyright
Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.