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Conception et validation d'un capteur noyé de résistivité électrique en vue du suivi des profils de teneur en eau dans les bétons

Abstract : Electrical resistivity is a parameter sensitive to various properties of concrete, including water content, which is one of the key parameters governing concrete long-term durability. In this study, the problem of monitoring the concrete water content profile throughout the concrete structure thickness is addressed using a method based on DC- electrical resistivity measurements. This is of great importance for concrete repository structures used for radioactive waste and for applications requiring centimetric resolution of the water content profile over a thick structure. The aim of this thesis is to design and produce a novel multi-electrode embedded sensor for monitoring the resistivity profile over depth in order to estimate the water content profile. The study focuses on the design of two sensors based on printed circuit board (PCB), which brings several advantages, including geometric accuracy and mitigation of wiring issues, in order to increase the durability of the sensors and to reduce invasiveness. Different measurement configurations are analyzed and compared. In addition, numerical modeling of the sensor response and its ability to assess an imposed resistivity profile is carried out, as well as the influence of the steel reinforcement on the response of the sensors placed in the center of the reinforcement mesh. Experimental validations using saline solutions of known conductivity and concrete specimens subjected to drying are studied. The results demonstrate the capability of the sensor to evaluate resistivity profiles in concrete with centimetric resolution. To enlarge our scale and approach real structures, the sensors are embedded in two 30 cm thick concrete slabs instrumented by other sensors to compare the results. Calibration of the measurements is carried out to determine the water content profile taking the temperature into account. The saturation degree profiles obtained with the innovative sensors developed in this thesis are compared to the profiles obtained from reference measurements (thermohygrometric sensors and gammadensimetry) and give consistent results with the evolution of the concrete due to drying.
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Submitted on : Tuesday, June 2, 2020 - 4:37:09 PM
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  • HAL Id : tel-02735810, version 1

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Joanna Badr. Conception et validation d'un capteur noyé de résistivité électrique en vue du suivi des profils de teneur en eau dans les bétons. Matériaux composites et construction. Université Paul Sabatier - Toulouse III, 2019. Français. ⟨NNT : 2019TOU30153⟩. ⟨tel-02735810⟩

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