An innovative method for TDR measurement of static electrical conductivity in granular materials

Time domain reflectometry (TDR) is a robust approach for measuring static electrical conductivity of moistened granular materials. Although initially introduced for monitoring soil salinity, its application to granular materials might be an interesting and cost-effective means for monitoring the quality-status of various materials. However, the traditional approach requires tedious and time-consuming preliminary calibration measurements on reference liquids. In this paper, an innovative approach for the direct estimation of the electrical conductivity is presented. In fact, it is demonstrated that the suitable combination of the TDR measurement with a transmission-line modeling of the measurement setup, successfully leads to the avoidance of the preliminary calibration procedure. Investigations carried out on water and on moistened sand samples demonstrate that the performance of the proposed method in estimating the static conductivity is comparable with that achievable through the traditional approach.