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Controlled-Humidity XRD Analyses: Application to the Study of Smectite Expansion/Contraction

Published online by Cambridge University Press:  06 March 2019

Steve J. Chipera ,
J. William Carey  and
David. L. Bish
Steve J. Chipera
Affiliation:
Earth and Environmental Sciences Division Los Alamos National Laboratory Mail Stop D469, Los Alamos, NM 87545
J. William Carey
Affiliation:
Earth and Environmental Sciences Division Los Alamos National Laboratory Mail Stop D469, Los Alamos, NM 87545
David. L. Bish
Affiliation:
Earth and Environmental Sciences Division Los Alamos National Laboratory Mail Stop D469, Los Alamos, NM 87545
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Abstract

Smectites are clay minerals that expand and contract dramatically in response to changes in water vapor pressure. The expansion/contraction behavior of smectite has considerable importance in engineering applications (such as the stability of building foundations and the integrity of clay barriers) and affects hydrologic properties. To understand this behavior we have analyzed several purified, homoionic smectite standards over a wide range of relative humidities using X-ray powder diffraction (XRD) and a new computer-automated humidity-control system.

Humidity was controlled by mixing dry N2 with H2O-saturated (“wet”) N2 produced with a gas-washing bubbler held in a constant-temperature bath set at 35°C. Mixing of wet and dry N2 was controlled with automated MKS mass-flow controllers.

Type
Research Article
Information
Advances in X-Ray Analysis , Volume 39: Forty-Fourth Annual Conference on Applications of X-ray Analysis, July 31 - August 4, 1995 , 1995 , pp. 713 - 722
Copyright
Copyright © International Centre for Diffraction Data 1995

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References

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