Soutenance de thèse Marcela TORRES LUQUE – “Development of a capacitive sensor for assessing chloride ingress into porous materials: design for reinforced concrete structures”

RÉSUMÉ:

Reinforced concrete (RC) is a material widely used in the construction of civil engineering facilities because of its high durability. However, there are some environmental actions that can considerably affect their performance, serviceability and safety. Among these actions, chloride ingress leads to corrosion of reinforcing bars that decreases structural capacity. Consequently, the assessment of chloride ingress mechanism into concrete becomes paramount for an optimum management of corroding RC infrastructure.
The main objective of this thesis is to develop a new embedded sensor for chloride measuring: the Chloride Capacitive Sensor (CCS). This is based on solutions that combine knowledge from three fields: civil engineering, electronics and materials science.
In order to develop the CCS, commercial calcium aluminate (CA) is tested as selective layer for the device. This material shows good potential for this task because its relative permittivity increases as chloride concentration rises at a rate of 1.391 /M.
The suitability of the sensor design is also verified. The results indicate that chloride concentration significantly affects the relative impedance of CA inside the sensor. Likewise, the proposed device has a limit of detection of 0.01 w/w %Cl, a sensitivity of 0.06 w/w %Cl, and a response time of at least 2 minutes under lab conditions. The results indicate that this sensor can be an efficient way for chloride assessment in porous materials.

JURY:

Directeurs de thèse:

Franck SCHOEFS, Professeur, Université de Nantes (Directeur de thèse France)
Mauricio SÁNCHEZ-SILVA, Professeur, Universidad de los Andes (Directeur de thèse Colombie)

Co-directeur:

Emilio BASTIDAS-ARTEAGA, Maître de conférences, Université de Nantes

Rapporteurs:

Muhammed BASHEER, Professeur, University of Leeds
Xosé Ramón NOVOA, Professeur, Universitade de Vigo

Examinateur:

Johan OSMA, Profesor asistente, Universidad de los Andes

Invité:

Abdou DJOUADI, Professeur, Université de Nantes