Laboratory Measurement of the Low-Frequency Electrical Properties of Sand

The electrical properties of soil in the lower part of the radio-frequency range are important for many engineering applications. This work investigates the dependence of soil electrical properties upon frequency and soil parameters through laboratory experiments. The soils under test consisted of two natural silica sands of uniform gradations. Measurements were conducted by using two-electrode experimental arrangements with guard electrodes; emphasis was given on their calibration. A method is introduced to estimate approximately the critical frequency below which measurement results are affected considerably by electrode polarization effects. The principal low-frequency polarization mechanism is interfacial polarization; the latter causes with increasing frequency a decrease of the real relative permittivity and an increase of the effective conductivity due to polarization losses.