• Babaei, Saeid

Abstract

Cementitious materials are the main pillar of modern construction and urbanization. With their endless practical applications and diversity of utilization from small village houses to skyscrapers, power plants and even nuclear waste disposal structures, they can be seen everywhere. The main driver for this study was to investigate the thermo-hydro-mechanical (THM) behaviour of cementitious engineered barriers, in particular, the barrier for high level nuclear waste containers considered in the Belgian deep geological disposal program. This thesis proposes a stepwise, multi-component and multiscale framework to model thermo-hydro-mechanical (THM) behavior of cementitious materials starting from microstructural modelling by representing microstructure of the material based on its chemical composition and reaction condition (curing, age, temperature, etc.). This modelling tool is then coupled with an algorithmic scheme adapted to convert such microstructure to a representative pore network and simulate transport properties. Regarding the mechanical and thermal properties, including elastic modulus, coefficient of thermal expansion and heat conduction coefficient a micromechanical scheme has been implemented by means of numerical homogenization. Finally, a multiscale and microstructure-informed THM simulationof an engineered barrier for high level nuclear waste container is carried out, where the material parameters are derived using the hydro-mechanical framework. The main objective of this application is to identify spatial regions of the engineered barrier that are prone to crack formation and propagation due to evolving thermal load and its consequences to hydro-mechanical behaviour of the barrier.

Topics

• impedance spectroscopy
• microstructure
• pore
• crack
• chemical composition
• thermal expansion
• homogenization
• curing