The CESAREF project is a Doctoral Network (DN), supported by the European Commission, to generate a Concerted European action on Sustainable Applications of REFractories. In the current context of the European Green Deal, this ambitious project has been launched in 2022 in order to develop a better knowledge around refractory materials with regards to the new operating conditions requested by the drastic reduction of greenhouse gas emissions, improved energy efficiency, and by life cycle assessment requirements. The present PhD study is focused on developments of numerical tools based on the discrete element method (DEM) for investigation of the relationships between microstructure and thermomechanical properties of model materials. This original numerical approach includes debounding, thermomechanical coupling, crack-closure and anisotropic behaviours. These developments will lead to a “virtual numerical lab” able to provide tensile, dilatometry, fracture mechanics or thermal shock virtual tests for virtual characterizations. The related achievements will be integrated to the free DEM software GranOO. Obtained numerical results will be validated in regard to experimental observations in terms of (i) mesoscopic thermomechanical quantities such as CTE, Young’s modulus, Poisson’s ratio, stress-strain law and fracture energy and (ii) microscopic observations such as fracture coalescence under thermal and mechanical loadings dynamically observed in SEM.