See more from this Session: General Soil Physics: II (Includes Graduate Student Competition)
Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level
This effort is directed at understanding the mechanisms that contribute to the water content of clays using dielectric spectroscopy. In this study we used Kaolinite Al2O3·2SiO2·2H2O and Bentonite 2Al2O3·5SiO2·5H2O with as-received water content. Using dielectric spectroscopy the phase-angle peak frequency for Kaolinite was 1 Hz and for Bentonite 20 kHz at room temperature. These peak frequencies differ by more than four orders of magnitude. Mixtures of approximately 2 g were prepared anticipating that two peaks would be observed but surprisingly only one major peak appeared in the phase-angle spectra. The peak frequency depends on the Bentonite to Kaolinite ratio progressing from 1 Hz to 20 kHz as the Bentonite content is increased. An examination of the spectra reveals that the polarization mechanism cannot be explained by Maxwell-Wagner for the conductivity does not level off at the lowest measured frequency (0.01 Hz). It appears that during the mixing operation, residual moisture quickly responds to the new matrix which leads to a single Debye-like polarization process. This talk will describe the various spectra observed along with their temperature dependences.