期刊
CEMENT AND CONCRETE RESEARCH
卷 41, 期 1, 页码 20-29出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.cemconres.2010.09.001
关键词
Calcium-silicate-hydrate (C-S-H); Elastic moduli; Micromechanics; Mechanical properties; Statistical nanoindentation
资金
- European Community [MRTN-CT-2005-019283]
- Ministry of Education, Youth and Sports of the Czech Republic [MSM6840770003]
- Lubomir Kopecky [MSM6046137302]
Several open questions related to the experimental protocol and processing of data acquired by the nano-indentation (NI) technique are investigated. The volume fractions of mechanically different phases obtained from statistical NI (SNI) analysis are shown to be different from those obtained by back-scattered electron (BSE) image analysis and X-ray diffraction (XRD) method on the same paste. Judging from transmission electron microscope (TEM) images, the representative volume element of low-density calcium-silicate hydrates (C-S-H) can be considered to be around 500 nm, whereas for high-density C-S-H it is about 100 nm. This raises the question how the appropriate penetration depth for NI experiments should be selected. Changing the maximum load from 1 mN to 5 mN, the effect of penetration depth on the experimental results is studied. As an alternative to the SNI method, a manual indentation method is proposed, which combines information from BSE and atomic-force microscopy (AFM), coupled to the NI machine. The AFM allows to precisely indent a high-density C-S-H rim around unhydrated clinkers in cement paste. Yet the results from that technique still show a big scatter. (C) 2010 Elsevier Ltd. All rights reserved.
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