A novel instrument for characterising the electrical properties of dry granular-porous materials

Understanding soil electrical properties is essential for estimating the soil water content and salinity through methods adopting electrical measurements and sensors. Several low-cost soil water content sensors have been developed in the last years for geotechnical and agronomic applications, but for their validation, a characterisation process is required. This is usually performed with liquids whose electric properties are known in the literature. Soils electrical properties are unknown in prior due to the number of factors impacting them. However, their knowledge could help to characterise sensors for their application in the field. This work presents a new system based on cylindrical capacitors that could be used to estimate the soil electrical properties. The analytical model used in the estimation is obtained from the Gauss's Law and the estimation error is evaluated. Some measurements at low frequency, 10-100 kHz range, are performed for dry granular-porous materials.