Single-crystal elastic constants of natural ettringite

Sergio Speziale, Fuming Jiang, Zhu Mao, Paulo J.M. Monteiro, Hans Rudolf Wenk, Thomas S. Duffy, Frank R. Schilling

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

The single-crystal elastic constants of natural ettringite were determined by Brillouin spectroscopy at ambient conditions. The six non-zero elastic constants of this trigonal mineral are: C11 = 35.1 ± 0.1 GPa, C12 = 21.9 ±0.1 GPa, C13 = 20.0 ± 0.5 GPa, C14 = 0.6 ± 0.2 GPa, C33 = 55 ± 1 GPa, C44 = 11.0 ± 0.2 GPa. The Hill average of the aggregate bulk, shear modulus and the polycrystal Young's modulus and Poisson's ratio are 27.3 ± 0.9 GPa, 9.5 ± 0.8 GPa, 25 ± 2 GPa and 0.34 ± 0.02 respectively. The longitudinal and shear elastic anisotropy are C33/C11 = 0.64 ± 0.01 and C66/C44 =0.60 ± 0.01. The elastic anisotropy in ettringite is connected to its crystallographic structure. Stiff chains of [Al(OH)6]3- octahedra alternating with triplets of Ca2+ in eight-fold coordination run parallel to the c-axis leading to higher stiffness along this direction. The determination of the elastic stiffness tensor can help in the prediction of the early age properties of cement paste when ettringite crystals precipitate and in the modeling of both internal and external sulfate attack when secondary ettringite formation leads to expansion of concrete.

Original languageEnglish (US)
Pages (from-to)885-889
Number of pages5
JournalCement and Concrete Research
Volume38
Issue number7
DOIs
StatePublished - Jul 1 2008

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Materials Science(all)

Keywords

  • Brillouin spectroscopy
  • Crystal structure
  • Elastic moduli
  • Sulfate

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