Ettringite Research Papers - Academia.edu (original) (raw)
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The structure of the ettringite mineral was studied by means of FTIR spectroscopy and single crystal X-ray diffraction method. The experimental study was combined with the first principle calculations based on density functional theory... more
The structure of the ettringite mineral was studied by means of FTIR spectroscopy and single crystal X-ray diffraction method. The experimental study was combined with the first principle calculations based on density functional theory (DFT) method. Predicted structural parameters (unit cell vectors and positions of heavy atoms) are in a very good agreement with the experimental data. Moreover, calculations also enabled to refine the positions of the hydrogen atoms not determined precisely by the single crystal X-ray measurement. The detailed analysis of the hydrogen bonds in the ettringite structure was performed and several groups of the hydrogen bonds were classified. It was found that the water molecules from the coordination sphere of Ca 2þ cations act as proton donors in moderate OeH$$$O hydrogen bonds with SO 2À 3 anions. Further, multiple OeH$$$O hydrogen bonds were identified among water molecules themselves. In addition, also hydroxyl groups from the [Al(OH) 6 ] 3À octahedral units are involved in the weak OeH$$$O hydrogen bonding with the water molecules. The calculated vibrational spectrum showed all typical features observed in the experimental FTIR spectrum. Moreover, performing the analysis of the calculated spectrum, all vibrational modes were distinguished and assigned. Such a complete analysis of the measured IR and/or Raman spectra is not fully possible, specifically for the region below 1500 cm À1 , which is characterized by a complex curve with many overlapped bands. A comparison of the vibrational spectra of ettringite and thaumasite (mineral structurally similar to ettringite) revealed the origin of the most important differences between them.
The formation, structure and chemistry of the ettringite and C---S---H phases of Portland cement have been reviewed as they relate to waste ion immobilization. The purpose of this review was to investigate the use of Portland cement as a... more
The formation, structure and chemistry of the ettringite and C---S---H phases of Portland cement have been reviewed as they relate to waste ion immobilization. The purpose of this review was to investigate the use of Portland cement as a host for priority metallic pollutants (Cr, Pb, ...