Comparison of two dielectric sensors in coarse-grained soils of increasing salinity

Moisture content can impact the resilient modulus (MR) of pavement base course and subgrade layers. Given its influence on the post-inundation MR of the coastal pavement and base course and subgrade layers, it is important for transportation management personnel to understand the post-inundation moisture state for short-term and long-term planning. Dielectric soil moisture sensors can be used to obtain real-time soil moisture data; however, in coastal areas these sensors will be exposed to salinity. In this study, the performance of two commercially available dielectric soil moisture sensors, one using Time Domain Reflectometry (TDR) technology and one using capacitance technology, in a laboratory environment with three different soil materials was examined. Both sensors measure volumetric water content (θ), bulk electrical conductivity (σb) and temperature. Volumetric water content values from the sensors were compared to gravimetrically obtained values. The results show that the capacitance sensor was more reliable and more accurately measured volumetric water content in all three soil materials.