Thermal resistivity
The thermal resistivity of the soil is measured in our laboratory with a needle probe and unfortunately it is not constant. This is because it depends on the soil type, its mineralogy, as well as its phase composition.
In addition to resistivity, the measuring system we use continuously measures the water content of the sample, which is constantly reduced due to evaporation. This enables us to determine the dependence of water content and thermal resistivity in a short time and to derive relevant characteristic values, such as the critical water content. Our measurement system is in compliance with IEEE 442-2017 and ASTM D5334-22.
Application and Potential
The thermal resistivity of the soil is important for the selection and verification of the bedding material of buried cables. Furthermore, it is crucial for the design of efficient geothermal collectors or the dimensioning of a ground freezing system. In combination with statements on the water potential of the soil, the thermal resistivity is also a relevant parameter in soil science.
Specimen Requirements
- Undisturbed or restored samples
- Minimum sample quantity 1 kg per test
Technical Equipment
- Several fully automated test benches for the measurment of the thermal dry-out-curve
Further information
- IEEE 447-2017: Guide for Thermal Resistivity Measurements of Soils and Backfill Materials
- ASTM D5334-22: Standard Test Method for Determination of Thermal Conductivity of Soil and Rock by Thermal Needle Probe Procedure