Use of dielectric spectroscopy to estimate ice content in frozen porous media

[1] We investigate the use of dielectric spectroscopy to estimate ice content in frozen porous media. A dielectric mixing model was used to determine the volumetric fractions of the different phases, based on knowledge of the bulk and single-phase dielectric permittivities. Measurement of the dielectric permittivities at two different frequencies with an impedance analyzer is required to infer ice content. One of the frequencies (25 kHz) has to be close to the relaxation frequency of ice; the other frequency (158 kHz or higher) must be well above the relaxation frequency of ice to obtain a different permittivity value of the ice phase. The theory was tested with three soil samples containing different amounts of clay. Dielectric permittivities of the soil samples were determined between 0.1 and 200 kHz, and in the temperature range of - 30 degreesC to + 5 degreesC. Ice content was successfully determined for a loamy sand sample. However, surface phenomena at low frequencies ( such as double-layer polarization, surface conduction, and Maxwell-Wagner type effects) made ice content estimation using our proposed methods unfeasible in silty loam and clay samples, which had 13% and 46% clay by weight, respectively.