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Pressure induced reactions amongst calcium aluminate hydrate phases |
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| Authors: | Ju-hyuk Moon Jae Eun Oh Magdalena Balonis Fredrik P. Glasser Simon M. Clark Paulo J.M. Monteiro |
| Affiliation: | aDepartment of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA;bSchool of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan Metropolitan City, 689-798, South Korea;cDepartment of Chemistry, Meston Building, University of Aberdeen, Aberdeen, AB24 3UE Scotland, UK;dAdvanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA20015, USA;eDepartment of Earth and Planetary Sciences, University of California, Berkeley, CA94720, USA |
| Abstract: | The compressibilities of two AFm phases (strätlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-pressure X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the pressure-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the pressure-induced dehydration is the dominant mechanism especially with hygroscopic pressure medium. The Birch–Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the pressure–volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies. |
| Keywords: | X-ray diffraction (B) High pressure Elastic moduli (C) Hydrogarnet (D) Calcium aluminate hydrates (D) |
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