X-ray photoelectron spectroscopic investigation of nanocrystalline calcium silicate hydrates synthesised by reactive milling
- Forschungszentrum Karlsruhe GmbH, Institut fuer Technische Chemie, Bereich Thermische Abfallbehandlung (ITC-TAB), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany) and Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB (United Kingdom)
- Forschungszentrum Karlsruhe GmbH, Institut fuer Technische Chemie, Bereich Thermische Abfallbehandlung (ITC-TAB), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
- Forschungszentrum Karlsruhe GmbH, Institut fuer Nukleare Entsorgung (INE), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
X-ray photoelectron spectroscopy (XPS) has been used to analyse a series of mechanochemically synthesised, nanocrystalline calcium silicate hydrates (C-S-H). The samples, with Ca/Si ratios of 0.2 to 1.5, showed structural features of C-S-H(I). XPS analysis revealed changes in the extent of silicate polymerisation. Si 2p, Ca 2p and O 1s spectra showed that, unlike for the crystalline calcium silicate hydrate phases studied previously, there was no evidence of silicate sheets (Q{sup 3}) at low Ca/Si ratios. Si 2p and O 1s spectra indicated silicate depolymerisation, expressed by decreasing silicate chain length, with increasing C/S. In all spectra, peak narrowing was observed with increasing Ca/Si, indicating increased structural ordering. The rapid changes of the slope of FWHM of Si 2p, {delta} {sub Ca-Si} and {delta} {sub NBO-BO} as function of C/S ratio indicated a possible miscibility gap in the C-S-H-solid solution series between C/S 5/6 and 1. The modified Auger parameter ({alpha}') of nanocrystalline C-S-H decreased with increasing silicate polymerisation, a trend already observed studying crystalline C-S-H. Absolute values of {alpha}' were shifted about - 0.7 eV with respect to crystalline phases of equal C/S ratio, due to reduced crystallinity.
- OSTI ID:
- 20871552
- Journal Information:
- Cement and Concrete Research, Vol. 36, Issue 6; Other Information: DOI: 10.1016/j.cemconres.2006.03.018; PII: S0008-8846(06)00079-2; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
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