COUPLED MEASUREMENTS OF WATER CONTENT AND ELECTRICAL CONDUCTIVITY IN DIELECTRICALLY LOSSY CLAY SLURRY USING A COATED TDR PROBE

摘要

References(20) Cited-By(1) Although time domain reflectometry (TDR) has been widely accepted as a non-destructive in-situ method with high reliability, the effective use of TDR for water content (w) and electrical conductivity (EC) measurements in clay slurry has not been established. We developed a Teflon-coated (TC) probe with a 0.05-mm thick fluorocarbon resin coating, and conducted a calibration experiment for kaolinite slurry to indicate its applicability to the measurements. The TC probe could estimate w from the observed effective dielectric constant (εeff) in the range of w≥47% with a ±6% error range. The εeff includes dielectric constant of two components: material under test (εm) and coating material (εtef). The relationship between εeff and w for this particular probe design cannot be directly applied to other coated probes because each probe has its own specific dielectric characteristic. We defined a function expressing the characteristic, that is εeff vs. εm, according to the testing in various fluid media. By applying the function, the observed data sets of εeff were transformed for a soil specific value (εm). Owing to the sufficient agreement of the εm values with those for the uncoated probe, we obtained the data sets of εm vs. w and its empirical expression for kaolinite slurry.