Impact of atmospheric carbonatation on hydrodynamic properties of concrete in the context of nuclear waste storage.
France, nuclear waste is managed by CIGEO, a deep geological storage site emphasizing reversibility over its 150-year lifespan. Material selection, notably concrete, is carefully chosen for its durability.
Concrete's pH protects steel reinforcement from corrosion, but factors like atmospheric carbonatation can accelerate corrosion. It is important to maintain a low corrosion rate to ensure the mechanical stability of reinforced concrete and prevent its deterioration.
Atmospheric carbonatation of concrete occurs when atmospheric CO2(g) diffuses into its porosity, leading to acidification of pore water through CO2(aq) solubilization. Dissolution of cement hydrates, like calcium hydroxide Ca(OH)2, buffers this acidification and forms secondary minerals, such as calcium carbonates CaCO3.
The rate of carbonatation front propagation depends on concrete's specific characteristics (e.g., porosity, permeability, initial water content, hydrate content) and environmental factors like CO2(g) concentration and atmospheric humidity.
You will conduct modeling work aimed at evaluating, at different time scales (from years to hundreds of years) and spatial scales (meso- and macroscopic scales), the impact of storage scenarios on the physical and chemical quality of concrete.
The modeling work should also allow for the decoupling of the various mechanisms resulting from concrete carbonatation through a sensitivity study.
The results will be used to (i) improve the fundamental understanding of the mechanisms underlying concrete carbonatation and (ii) provide an in-depth understanding of the long-term durability of containers, thereby providing decision-making tools for structure design.
Currently enrolled in a Master 2 or equivalent engineering school in environmental sciences, hydrogeology or geochemistry, you should have a keen interest in modeling and data processing.
Practical skills in reactive transport modeling in porous media will be appreciated.
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In accordance with CEA's commitment to the integration of people with disabilities, this job is open to everyone. The CEA offers accommodation and/or organisational possibilities.