Determination of the elastic constants of portlandite by Brillouin spectroscopy

作者：Speziale S^*; Reichmann H J; Schilling F R; Wenk H R; Monteiro P J M

来源：Cement and Concrete Research, 2008, 38(10): 1148-1153.

DOI：10.1016/j.cemconres.2008.05.006

• Ca(OH)(2)
• Elastic moduli
• Cement

The single crystal elastic constants C-ij and the shear and adiabatic bulk modulus of a natural portlandite (Ca(OH)2) crystal were determined by Brillouin spectroscopy at ambient conditions. The elastic constants, expressed in GPa, are: C-11=102.0(+/- 2.0), C-12=32.1(+/- 1.0), C-13=8.4(+/- 0.4), C-14=4.5(+/- 0.2), C-33=33.6(+/- 0.7), C-44=12.0(+/- 0.3), C-66=(C11-C12)/2=35.0(+/- 1.1), where the numbers in parentheses are 1 sigma standard deviations. The Reuss bounds of the adiabatic bulk and shear moduli are K-OS=26.0(+/- 0.3) GPa and G(O)=17.5(+/- 0.4) GPa, respectively, while the Voigt bounds of these moduli are K-OS=37.3(+/- 0.4) GPa and G(O)=24.4(+/- 0.3) GPa. The Reuss and Voigt bounds for the aggregate Young's modulus are 42.8(+/- 1.0) GPa and 60.0(+/- 0.8) GPa respectively, while the aggregate Poisson's ratio is equal to 0.23(+/- 0.01). Portlandite exhibits both large compressional elastic anisotropy with C-11/C-33=3.03 (+/- 0.09) equivalent to that of the isostructural hydroxide brucite (Mg(OH)(2)), and large shear anisotropy with C-66/ C-44=2.92(+/- 0.12) which is 11% larger than brucite. The comparison between the bulk modulus of portlandite and that of lime (CaO) confirms a systematic linear relationship between the bulk moduli of brucite-type simple hydroxides and the corresponding NaCl-type oxides.

• 出版日期2008-10