Critical aspects of nano-indentation technique in application to hardened cement paste
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.
- OSTI ID:
- 21490047
- Journal Information:
- Cement and Concrete Research, Vol. 41, Issue 1; Other Information: DOI: 10.1016/j.cemconres.2010.09.001; PII: S0008-8846(10)00205-X; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOMIC FORCE MICROSCOPY
CALCIUM SILICATES
CEMENTS
HYDRATES
IMAGE PROCESSING
MECHANICAL PROPERTIES
PENETRATION DEPTH
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
BUILDING MATERIALS
CALCIUM COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
MATERIALS
MICROSCOPY
OXYGEN COMPOUNDS
PROCESSING
SCATTERING
SILICATES
SILICON COMPOUNDS