A coupled nanoindentation/SEM-EDS study on low water/cement ratio Portland cement paste: Evidence for C-S-H/Ca(OH)2 nanocomposites

Jeffrey Chen 1, * Luca Sorelli 1 Matthieu Vandamme 2 Franz-Josef Ulm 3 Gilles Chanvillard 1
* Corresponding author
2 Multi-échelle
MIT - Massachusetts Institute of technology [Cambridge], NAVIER UMR 8205 - Laboratoire Navier
Abstract : A low water/cement ratio (w/c=0.20) hydrated Portland cement paste was analyzed by grid-indentation coupled with ex situ scanning electron microscope-energy-dispersive X-ray spectra (SEM-EDS) analysis at each indentation point. Because finite element and Monte-Carlo simulations showed that the microvolumes probed by each method are of comparable size (approximately 2 μm), the mechanical information provided by nanoindentation was directly comparable to the chemical information provided by SEM-EDS. This coupled approach provided the opportunity to determine whether the local indentation response was a result of a single- or a multiphase response--the latter being shown predominant in the highly concentrated w/c=0.20 hydrated cement paste. Results indicate that, in the selected microvolumes where C-S-H and nanoscale Ca(OH)2 (CH) are present, increasing fractions of CH increase the local indentation modulus (and hardness), yielding values above those reported for high-density (HD) C-S-H. Micromechanical analyses show that C-S-H and CH are associated, not merely as a simple biphase mixture, but as an intimate nanocomposite where nanoscale CH reinforces C-S-H by partially filling the latter's gel pores. The paper discusses the mechanism of forming the C-S-H/CH nanocomposite, as well as the impact of nanocomposites on various macroscopic properties of concrete (e.g., shrinkage, expansion). On a general level, this study illustrates how a coupled nanoindentation/X-ray microanalysis/micromechanics approach can provide otherwise inaccessible information on the nanomechanical properties of highly heterogeneous composites with intermixing at length scales smaller than the stress field in a nanoindentation experiment.
Document type :
Journal articles
Journal of the American Ceramic Society, Wiley-Blackwell, 2010, 93 (5), pp.1484-1493. <10.1111/j.1551-2916.2009.03599.x>


https://hal.archives-ouvertes.fr/hal-00555495
Contributor : Matthieu Vandamme <>
Submitted on : Monday, August 22, 2011 - 11:20:33 AM
Last modification on : Wednesday, April 15, 2015 - 4:11:32 PM

File

JACERS-26693-With-Figures.pdf
fileSource_public_author

Identifiers

Citation

Jeffrey Chen, Luca Sorelli, Matthieu Vandamme, Franz-Josef Ulm, Gilles Chanvillard. A coupled nanoindentation/SEM-EDS study on low water/cement ratio Portland cement paste: Evidence for C-S-H/Ca(OH)2 nanocomposites. Journal of the American Ceramic Society, Wiley-Blackwell, 2010, 93 (5), pp.1484-1493. <10.1111/j.1551-2916.2009.03599.x>. <hal-00555495>

Export

Share

Metrics

Consultation de
la notice

241

Téléchargement du document

176