HR: 1340h
AN: MR43C-1520 [Abstracts]
TI: The Elastic Properties of Natural Portlandite Ca(OH)2
AU: Speziale, S
EM: speziale@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: * Reichmann, H J
EM: hanni@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Schilling, F
EM: fsch@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Wenk, H R
EM: wenk@berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Science - University of
California, Berkeley, Berkeley, CA 94720-4767, United States
AU: Monteiro, P J
EM: monteiro@ce.berkeley.edu
AF: University of California, Berkeley, Department of Civil and Environmental Engineering -
University of California, Berkeley, Berkeley, CA 94720-1710, United States
AB:
Portlandite, Ca(OH) 2, is a simple hydroxide with brucite structure (space group P~{3}m1). It is
built up of layers of CaO6 octahedra stacked along the c-axis. Portlandite is of basic interest for the cement
and concrete research and industries, because it is a major primary solid phase in hydrated portland cement. It is
therefore of particular importance to determine the elastic properties of portlandite. So far a computational
(Laugesen, 2005) and an experimental (Holuj et al., 1985) study reported the single crystal elastic moduli
Cij. However, these results differ significantly in some off-diagonal moduli. We
performed Brillouin spectroscopy measurements on natural single crystal portlandite at ambient
conditions. Our measurements have been performed in a new Brillouin laboratory set up at the
Geoforschungszentrum, Potsdam. The new system features an Eulerian cradle with an inner diameter
of 400 mm, and it has been designed to accommodate an internally heated diamond anvil cell to perform
Brillouin measurements at high P and T conditions. We have obtained the following values for the
elastic moduli (expressed in GPa followed by 1σ uncertainty in parentheses): C11 = 102.0 (2.0),
C12 = 32.1 (1.0), C13 = 8.4 (0.4), C14 = 4.5 (0.2), C33 = 33.6 (0.7), C44 = 12.0 (0.3),
C66 = (C11-C12)/2 = 35.0 (1.5). With our new measurements we put a better constraint on the
value of C13 which is more than 2.5 times larger than reported by Holuj and coworkers, and is closer to the
value calculated by Laugesen. A remarkable feature of the elastic behavior is the high elastic anisotropy of
portlandite due to its highly anisotropic layered structure. The zero pressure Voigt and Reuss bounds to the
adiabatic bulk modulus of portlandite are: K0SV = 37.3 (0.4) GPa and K0SR = 26.0 (0.3) GPa,
with a 43% difference between the two bounds. The Voigt and Reuss bounds to the shear modulus are
G0V = 24.4 (0.4) GPa and G0R = 17.5 (0.3) GPa, with a 40% difference between the two
bounds. The large elastic anisotropy of portlandite is comparable to that of isostructural brucite Mg(OH)2.
DE: 3900 MINERAL PHYSICS
DE: 3909 Elasticity and anelasticity
DE: 3994 Instruments and techniques
DE: 3999 General or miscellaneous
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting