## 5 Conclusions  
Temperature and saturation degree of the concrete structure highly influence its resistivity measurements. In this paper, experimental results on embedded PCB resistivity sensors are presented and compared to empirical models of temperature and saturation degree. The use of innovative embedded PCB sensors offers the possibility of evaluating the concrete resistivity along the structure's depth as it is very important to evaluate the temperature contribution to the resistivity measurements for an accurate evaluation of water content in thick concrete structures. All measurements were performed under controlled conditions. Our experimental data behavior is highly consistent with well-established empirical models. Calibration curves that link the electrical resistivity with the degree of saturation at different temperatures (20, 45, and 60 \({}^{\circ}\)C) were established and shown to be consistent with Archie's Law. The profiles of resistivity versus temperature were found to conform to [PERSON] law. Therefore, parameters for standardization of measurements to definite values of temperature and saturation degree were obtained for the studied concrete. More generally, this study clearly shows that standardization of measurements with inadequate parameter values could yield misleading results.  
The main information obtained in this study concerns the function describing the evolution of resistivity versus saturation degree or temperature. The coefficients depend on the concrete mix. Thus, for new materials, we recommend a calibration that can be limited to very few adjustment points, which will save a lot of time while increasing the accuracy of the saturation degree evaluation attributed to resistivity at different temperatures.  
Conceptualization and methodology, all authors; experimentation, data collection, and analysis, J.B. and E.M.; writing--original draft preparation, J.B.; writing--review and editing, G.V., J.-P.B., S.P.L., Y.F. and B.Y. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Configuration** & **\(\Delta\)T (\({}^{\circ}\)C)** & **S.f(\%)** & **95.0 \(\pm\) 2.0\%** & **72.2 \(\pm\) 1.0\%** & **53.3 \(\pm\) 0.3\%** & **33.8 \(\pm\) 0.5\%** \\ \hline \multirow{2}{*}{Transmission} & 20–45 \({}^{\circ}\)C & 1.32 & 1.36 & 2.37 & 2.15 \\  & 45–60 \({}^{\circ}\)C & 2.29 & 2.69 & 2.72 & 3.80 \\ \hline \multirow{2}{*}{Wenner} & 20–45 \({}^{\circ}\)C & 1.35 & 2.33 & 2.25 & 2.50 \\  & 45–60 \({}^{\circ}\)C & 1.93 & 2.79 & 3.22 & 3.51 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Percentage change in resistivity per \({}^{\circ}\)C at different degrees of saturation and in two separate ranges of temperature for the transmission and Wenner configurations.  
**Funding:** This research was funded by Andra, Universite Gustave Eiffel, and Universite de Toulouse.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** The authors would like to thank [PERSON], [PERSON], and [PERSON] for the enriching discussions and fruitful exchanges and for their contributions to this study.  
**Conflicts of Interest:** The authors declare no conflict of interest.