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Proceedings Paper

Synchrotron x-ray microtomography and solid state NMR of environmental wastes in cement
Author(s): Leslie G. Butler; Frank K. Cartledge; John W. Owens; Betsy A. Dowd
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Paper Abstract

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures prepared with 1.22 to 3.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles with diameters ranging from 20 to 250 microns; a search with electron microscopy for vesicles in the range of 1 - 20 microns proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Evidence for toluene in the cement matrix comes from 29Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also, 2H NMR of d8-toluene/cement samples shows high mobility for all toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt%, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating from the cement paste and forming vesicular structures that are preserved in the cured cement. Furthermore, at loadings above 3 wt%, the abundance of vesicles formed during toluene/cement paste mixing leads to macroscopic phase separation.

Paper Details

Date Published: 22 September 1999
PDF: 8 pages
Proc. SPIE 3772, Developments in X-Ray Tomography II, (22 September 1999);
Show Author Affiliations
Leslie G. Butler, Louisiana State Univ. (United States)
Frank K. Cartledge, Louisiana State Univ. (United States)
John W. Owens, Southern Univ. (United States)
Betsy A. Dowd, Brookhaven National Lab. (United States)

Published in SPIE Proceedings Vol. 3772:
Developments in X-Ray Tomography II
Ulrich Bonse, Editor(s)

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