Single-crystal elastic constants of natural ettringite

Speziale, S.; Jiang, Fengxing; Mao, Zhu; Monteiro, Paulo J.M.; Wenk, Hans‐Rudolf; Duffy, Thomas S.; Schilling, Frank

doi:10.1016/j.cemconres.2008.02.004

Cited by 65 publications

(33 citation statements)

References 17 publications

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“…In ettringite the c-axis is the elastically stiffest direction (Speziale et al 2008a), contrary to portlandite (Ca(OH) 2 ) that also shows preferred orientation in veins (Detwiler et al 1988) and where the c-axis is elastically softest (Speziale et al 2008b). The single crystal elastic tensor of trigonal ettringite (C 11 =35.1GPa, C 12 =21.9, C 13 =20.0, C 14 =0.6, C 33 =55.0, C 44 =11.0) was averaged over the orientation distribution, using the geometric mean method (Matthies and Humbert, 1993) providing stiffness coefficients C 11 =36.3GPa, C 12 =21.7, C 13 =20.5, C 14 =0.0, C 33 =49.7, C 44 =10.6, assuming axial symmetry.…”

Section: Discussionmentioning

confidence: 99%

Preferred orientation of ettringite in concrete fractures

et al. 2009

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Sulfate attack and the accompanying crystallization of fibrous ettringite (Ca 6 Al 2 (OH) 12 (SO 4 ) 3 26H 2 O) causes cracking and loss of strength in concrete structures. We are using hard synchrotron X-ray microdiffraction to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed with the Rietveld method to obtain information on textures. The analysis reveals that c-axes of the trigonal minerals are preferentially oriented perpendicular to the fracture surfaces. By averaging single crystal elastic properties over the orientation distribution we can estimate the elastic anisotropy of ettringite aggregates. IntroductionPreferred orientation has considerable influence on the properties of a wide range of materials. Microtextures have been traditionally measured with backscatter electron diffraction (e.g. Dingley, 2004) but this technique fails if crystallites are strained and contain large numbers of defects. In this case a focused X-ray beam can be employed as it is available at synchrotron sources. Early applications of synchrotron X-rays for texture analysis has been to thin films (Player et al. 1992), plated alloys (Backstrom et al. 1996) and bone (Heidelbach et al. 1999). Since then the technique has greatly improved, especially by analyzing 2D images with the Rietveld method (Lonardelli et al. 2005). Here we apply the technique to a different material: microscopic veins in deteriorating concrete that are filled with the mineral ettringite.Concrete may be subject to sulfate attack that can cause expansion in the matrix of concrete and lead to loss of strength and stiffness because of lack of cohesiveness in the cement hydration products. The source of sulfate ions can be external or internal. For the external sulfate attack, the sulfate in groundwaters can penetrate the porous matrix of concrete and react with hydration products leading to expansion and cracking of the matrix. There is a consensus that the expansion in concrete is caused by the crystallization of ettringite Ca 6 Al 2 (OH) 12 (SO 4

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Section: Discussionmentioning

confidence: 99%

Preferred orientation of ettringite in concrete fractures

et al. 2009

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“…With reference to the ettringite, there is limited information available concerning its indentation properties. Based on the measurement of elastic constants of naturally occurring ettringite, along with Hill's averaging scheme [37], the estimated indentation modulus of this phase should approach M ≈ 28 ± 3 GPa, for ν = 0.34. Such a prediction is in very good agreement with the estimation of plane-strain modulus of polycrystalline ettringite inferred from the experimental measurements of elastic modulus of packed powder compacts and its estimate at zero porosity [38].…”

Section: Distribution Of the Mechanical Properties As Measured With Gmentioning

confidence: 99%

Inference of the phase-to-mechanical property link via coupled X-ray spectrometry and indentation analysis: Application to cement-based materials

Krakowiak

Wilson

James

et al. 2015

Cement and Concrete Research

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“…This work demonstrates that it is possible to determine the bulk modulus of ASR gel using X-ray absorption to measure density as a function of pressure (and hence the bulk modulus) [13][14][15][16]. Brillouin spectroscopy-which has already been used to determine the full elastic constants and averaged mechanical properties of cement crystalline phases ettringite and portlandite [17,18] -was employed to confirm the X-ray absorption result and to determine the shear modulus.…”

Section: Introductionmentioning

confidence: 98%