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References: ENV21-3

Themes: Themes : Engineering Sciences: Solid Mechanics, Materials, Civil Engineering

Thesis location: Research Laboratory for Migration and Interactions in the Geosphere (LETIS) - Fontenay-aux-Roses (92)

Start: October 2021

Skills required

Engineering school or university degree, specialization in materials mechanics -  Physico-chemical skills in cement materials desirable - Ability to conduct experimental study - Autonomous and rigorous
Age limit: 26 years old unless otherwise stated.

Thesis subject

For many decades, grouting/cementation has been recognised and deployed as a suitable treatment route for the immobilisation of radioactive waste streams due to its simplicity of casting, the low cost production and the good chemo-mechanical properties of , cementitious materials A number of cement binders have been developed and tailored to adapt to the diversity of nuclear wastes. All these cement materials might be subject to a wide range of disturbances which may lead to degradation of their chemo-mechanical properties: temperature, chemistry of this environment, interaction cement matrix/wastes, irradiation… Besides, a particularity of wasteconditioning cementitious matrix is to be exposed to irradiation from the cast. Nowadays, the effect of irradiation on the chemo-mechanical properties is investigated on hardened sample and do not take account the irradiation as phenomenon which may modify the initial chemo-mechanical properties of the cement matrix. Only recently some studies has been devoted to explore the disturbance due to irradiation at early young age of cement matrix. The proposed PhD follows this approach by studying the chemo-mechanical modification during the first hours of hydration of cement matrix subject to gamma irradiation. To reach this goal, several cement binders will be cast and exposed to gamma irradiation during the hydration process then the structure, the chemistry, the mechanical properties and the transport properties will be characterized. The PhD student will work at IRSN facilities located at Fontenay aux roses France within the SErvice des Déchets radioactifs et des transfeRts dans la géosphèrE (SEDRE). Some experiments could be perform at the Laboratoire d’Etude du Comportement des Bétons et des Argiles (LECBA) du CEA de Saclay France.