Environmental Engineering Reference
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Fig. 5.14
TDR waveforms acquired at longer distances on nine electrolyte solutions differing
in reference electrical conductivities (left). The behavior of the same waveforms at the steady-
state condition is also reported (right) [13]
the static reflection coefficients and the corresponding evaluated uncertainties were
referred to this range.
Successively, the values of the electrical conductivities (
σ
0
,
TLM
) of the electrolyte
solutions were also evaluated through the TLM method using, however, the same
TDR waveforms. To this purpose, preliminary TDR measurements with the probe
in air and in pure water were performed in order to obtain the optimized values for
the TLM model parameters, as discussed in the previous sections.
Furthermore, considering the TDR-probe in air and in pure water, and performing
capacitance measurements, the probe constant deriving from the ICM method was
estimated, as detailed in the previous sections. Results are summarized in Table 5.3,
in which the measured
C
m
, and the estimated
K
p
,
ICM
are reported along with the
corresponding absolute standard uncertainties.
The electrical conductivities deriving from the ICM method,
σ
0
,
ICM
,wereevalu-
ated for the electrolyte solutions.
Table 5.4 shows the comparison between the experimental results for
σ
0
,
TLM
and
σ
0
,
ICM
, obtained on the reference electrolyte solutions. The good agreement among
results provides a useful preliminary validation of the two considered approaches.
After the preliminary validation of the method on reference electrolyte solutions,
the described methods were used to measure the electrical conductivity of moist-
ened sand. To this purpose, sand samples were watered at ten different moisture
levels (ten samples were moistened with de-ionized water and ten with salted wa-
ter), thus obtaining a wide range of experimental conditions. TDR waveforms at
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