Iron in carbonate containing AFm phases

Dilnesa, B.Z.; Lothenbach, B.; Le Saout, G.; Renaudin, G.; Mesbah, A.; Filinchuk, Y.; Wichser, A.; Wieland, E.

doi:10.1016/j.cemconres.2010.11.017

Iron in carbonate containing AFm phases

Dilnesa BZ, Lothenbach B, Le Saout G, Renaudin G, Mesbah A, Filinchuk Y, Wichser A & Wieland E

Citation

Dilnesa, B. Z., Lothenbach, B., Le Saout, G., Renaudin, G., Mesbah, A., Filinchuk, Y., … Wieland, E. (2011). Iron in carbonate containing AFm phases. Cement and Concrete Research, 41(3), 311-323. https://doi.org/10.1016/j.cemconres.2010.11.017

Persistent URL https://www.dora.lib4ri.ch/empa/islandora/object/empa:4654

One of the AFm phases in hydrated Portland cement is Ca₃(Al_xFe_{2 − 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 °C, while Fe-hemicarbonate (Fe-Hc) was unstable with respect to Fe-Mc in the presence of calcite. Fe-Mc has a rhombohedral R3̅c 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 °C and 50 °C. Under standards condition the solubility products and other thermodynamic parameters were estimated using temperature-solubility product extrapolation and found to be logK_S0 (Fe-Mc) = −34.59 ± 0.50, logK_S0 (Fe-Hc) = −30.83 ± 0.50 and logK_S0(Al-Mc) = −31.32 ± 0.50.