Papers Published

1. Rose, Jerome and Moulin, Isabelle and Masion, Armand and Bertsch, Paul M. and Wiesner, Mark R. and Bottero, Jean-Yves and Mosnier, Francis and Haehnel, Claude, X-ray absorption spectroscopy study of immobilization processes for heavy metals in calcium silicate hydrates. 2. Zinc, Langmuir, vol. 17 no. 12 (2001), pp. 3658 - 3665 [la001302h] .
   (last updated on 2007/04/09)

   Abstract:
   Tricalcium silicate (C₃S), the major phase of cement-based materials, contains naturally a few hundred parts per million of heavy metals. An X-ray absorption spectroscopy (XAS) study at the Zn K-edge has been carried out to elucidate the binding mechanisms of Zn by calcium silicate hydrates, which is important to predict the long-term behavior of Zn. At low concentration, under the threshold of precipitation of the oxide, oxy hydroxide, and calcium zinc hydroxide, no retardation of the hydration of the C₃S has been observed for C₃S doped with Zn. A previous ²⁹Si NMR (Moulin, I.; Stone, W.E.E.; Sanz, J.; Bottero, J.-Y.; Mosnier, J.-Y.; Haehnel, C. Langmuir 1999, 15, 2829-2835) study has demonstrated that the structure of the hydrated C₃S (called C-S-H for calcium silicate hydrates) does not change if Zn is present initially or not. XAS experiments have shown that Zn tetrahedra are incorporated within the matrix of C-S-H and linked directly at the end of the silicate chains through Zn-O-Si bonds. The Zn-Si distance is approximately equals 3.1 A. Extended X-ray absorption fine structure results have been confirmed by ab initio calculations including multiple scattering.

   Keywords:
   Hydrates;Silicates;Precipitation (chemical);Doping (additives);Nuclear magnetic resonance;Chemical bonds;Scattering;X ray spectroscopy;