Evaluation of Two Thermo-TDR Probes for Soil Moisture, Density, and Thermal Conductivity

  • Xuelin Wang
  • Xinbao Yu
Conference paper


Thermo-TDR probes can function both as a regular time domain reflectometry (TDR) probe, for measuring moisture and density, and a dual-heat probe for measuring thermal conductivity, thermal diffusivity, and volumetric heat capacity. The probe measurement sensitivity and accuracy are affected by probe length, diameter, and spacing. In this paper, two thermo-TDR probes were fabricated based on an improved design of a previous one. The two probes were first calibrated for measurement of dielectric constant and electrical conductivity using standard chemical solutions. Then, moisture, density, and thermal measurements were taken in custom designed compaction molds filled with ASTM fine-grade compacted sand using the thermo-TDR probes as well as KD2 probes. Calibrations are reported for the thermo-TDR probes measuring soil moisture, density, and thermal conductivity. The effect of sensor fabrication and sample preparation tests are evaluated. Recommendations are provided for using thermo-TDR probes for measuring in sand.


Thermo-TDR probe Thermal conductivity Soil compaction Fabrication effect 


  1. Baker, J.M., Allmaras, R.R.: System for automating and multiplexing soil moisture measurement by time-domain reflectometry. Soil Sci. Soc. Am. J. 54(1), 1–6 (1990)CrossRefGoogle Scholar
  2. Blackwell, J.H.: The axial-flow error in the thermal-conductivity probe. Can. J. Phys. 34(4), 412–417 (1956)CrossRefGoogle Scholar
  3. De Vries, D.A.: A non-stationary method for determining thermal conductivity of soil in SITU. Soil Sci. 73(2), 83–89 (1952)CrossRefGoogle Scholar
  4. Giese, K., Tiemann, R.: Determination of the complex permittivity from thins sample time domain reflectometry: implications for twin rod probes with and without dielectric coatings. Water Resour. Res. 32(2), 271–279 (1975) Google Scholar
  5. Kluitenberg, G.J., Ham, J.M., Bristow, K.L.: Error analysis of the heat pulse method for measuring soil volumetric heat capacity. Soil Sci. Soc. Am. J. 57(6), 1444–1451 (1993)CrossRefGoogle Scholar
  6. Liu, X., Ren, T., Horton, R.: Determination of soil bulk density with thermo-time domain reflectometry sensors. Soil Sci. Soc. Am. J. 72(4), 1000–1005 (2008)CrossRefGoogle Scholar
  7. Ren, T., Noborio, K., Horton, R.: Measuring soil water content, electrical conductivity, and thermal properties with a thermo-time domain reflectometry probe. Soil Sci. Soc. Am. J. 63(3), 450–457 (1999)CrossRefGoogle Scholar
  8. Topp, G.C., Davis, J.L., Annan, P.: Electromagnetic determination of soil water content: measurements in coaxial transmission lines. Water Resour. Res. 16(3), 574–582 (1980)CrossRefGoogle Scholar
  9. Welty, J.R., Wicks, C.E., Wilson, R.E.: Fundamentals of Momentum, Heat, and Mass Transfer, 2nd edn. Wiley, New York (1976). OCLC 2213384. ISBN 978-0-471-93354-0Google Scholar
  10. Yu, X., Drnevich, V.P.: Soil water content and dry density by time domain reflectometry. J. Geotech. Geoenviron. Eng. 130(9), 922–934 (2004)CrossRefGoogle Scholar
  11. Yu, X., Zhang, N., Pradhan, A., Thapa, B., Tjuatja, S.: Design and evaluation of a thermo-TDR probe for geothermal applications. Geotech. Test. J. 38(6), 864–877 (2015)CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Department of Civil EngineeringUniversity of Texas at ArlingtonArlingtonUSA

Personalised recommendations