Thesis defense of Houssein IBRAHIM
Houssein IBRAHIM, PhD student at Lames, Université Gustave Eiffel, has defended his thesis entitled
"Development of Embedded Capacitive Sensors for Determining Water Content Gradients in
Reinforced Concrete Structures"
on
friday november 22d 2024
at 2.00 PM at the amphitheatre of Université Gustave Eiffel, campus of Nantes (France)
The thesis has been presented before the following jury:
| Reporters : Jean-François LATASTE Stéphane RIOUAL | Professeur des universités, Université de Bordeaux Maitre de conférences, HDR, Université de Bretagne occidentale |
| Examinators : Karim AIT MOKHTAR Emmanuel ROZIERE Narintsoa RANAIVOMANANA Fréderic TAILLADE | Professeur des universités, Université de La Rochelle Professeur des universités, Ecole Centrale de Nantes Maitre de conférences, Université de Toulouse 3 Docteur, HDR, EDF |
| Thesis Directors : Géraldine VILLAIN, director Jean-Paul BALAYSSAC, co-director | Ingénieur Divisionnaire des TPE, HDR, Université Gustave Eiffel, Nantes Professeur des universités, Université Toulouse 3 |
| Supervisors : Xavier DÉROBERT Sérgio PALMA LOPES Narintsoa RANAIVOMANANA | Ingénieur Divisionnaire des TPE, HDR, Université Gustave Eiffel, Nantes Ingénieur Divisionnaire des TPE - Université Gustave Eiffel, Nantes Maitre de conférences, Université de Toulouse 3 |
Abstract:
Reinforced concrete structures experience various forms of deterioration that impact their lifespan. To assess these degradations, destructive (D), non-destructive (ND), and Structural Health Monitoring (SHM) methods are used, as demonstrated in the ANRSCaNING project. This project embeds sensors in structures to continuously monitor key indicators like compressive strength, Young's modulus, porosity, and saturation degree.
The main objective of the thesis is to design a capacitive multi-electrode sensor for measuring water content or saturation profiles in concrete.
Measurements, based on oscillation frequency, are calibrated first for dielectric permittivity and then for water content (or degree of saturation).
The sensor's geometry was optimized for sensitivity, featuring 8 electrode pairs to measure 8 different depths. After calibration and testing in concrete blocks, the sensor showed consistent measurements with a 7% deviation in permittivity. Temperature corrections were developed, and final tests in a concrete slab confirmed that the sensor's results aligned with other saturation measurement reference methods, resistivity and thermohygrometric method, showing less than 10% variation in saturation profiles.
Keywords: Concrete durability, Embedded sensors, Dielectric permittivity, Capacitive method, Water content.