Description du sujet de thèse

The crystallization of one or more salts in a porous medium (rocks, soils, building materials, etc.) resulting from evaporation is a subject of major interest in connection with many issues such as salinization of soils, evaporation of soils, injection of CO2 in saline aquifers, durability of building materials or preservation of our cultural heritage, all this in a context where climate change is likely to amplify the damage related to salts.
The objective of the proposed thesis is to advance knowledge in this field of research using microfluidics. Thanks to microfabrication, these techniques allow the realization of networks of interconnected channels seen as prototypes of quasi-bidimensional model porous media. A decisive advantage of these systems is to allow the direct observation of the development of salt structures within the porous network.
In a first part, the study will focus on the development and growth of the salt structure within the network as a function of two main parameters (average channel size and evaporation rate).
In a second part, crystallization experiments will be developed on deformable networks, in order to evaluate the stresses resulting from crystallization. For this purpose, quantitative techniques allowing to link deformation of the material and stresses, such as traction force microscopy, will be implemented.

Required skills:
This subject being mainly based on experimental and imaging techniques, it is suitable for candidates of Master / engineering school level interested in manufacturing techniques, experimental work and image acquisition and processing techniques. A background in fluid mechanics and/or physics and/or physical chemistry and/or microfabrication is a plus for this subject.

Contexte de travail

The thesis will take place at the Laboratory of Analysis and Architecture of Systems (LAAS) in the MILE microfluidics team, in close collaboration with the Institute of Fluid Mechanics of Toulouse. It is part of the ANR project "DRYSALT" and the work will therefore be in interaction with two other laboratories: the Sols, Solides, Structures, Risques (3SR) laboratory in Grenoble and the Matériaux et Durabilité des Constructions (Materials and Construction Durability) laboratory in Toulouse.
Starting date: september or october 2023