In contact with an aggressive environment and due to internal physico-chemical phenomena, the structure and the composition of a material evolves and differential strain can occur. This evolution is intimately connected to the gradient phenomena induced by diffusion of chemical species or temperature. Two topics will be treated: the long-term behavior of cementitous materials and crack propagation and healing in nuclear fuel pellet. Attention is directed towards the coupling of diffusion and mechanical problems, which is crucial for both phenomena of interest. In these systems, the diffusion of fields, as chemical species or temperature in this study, induces a gradient of delayed deformation, i.e chemical strain or thermal dilatation respectively. Cracks initiate due to these differential strains which impact the diffusion field. For chemical attacks, cracks are preferred locii for ions diffusion and may accelerate geomaterial degradation. From thermo-mechanical standpoint, cracks have a resistive impact on the thermal field, which modifies the microstructure's evolution and thermal strain. In that way, the cracks have to be introduced in the diffusion model to improve the prediction of chemical attacks and thermal loadings. Two descriptions of cracks will be discussed. Discontinuous approach dealing with the Cohesive Zone Model able to estimate the local crack aperture and discontinuities, can modify the field by considering the crack geometry [1,2]. The continuous problem dealing with damage and phase field approach, where cracks are not directly described, can be easily coupled with diffusion model such as the reactive transport software Hytec [3]. Both approaches will be presented and we will outline the advantages and disadvantages of each model. [1] Socié, A., Dubois, F., Monerie, Y. et al. Multibody approach for reactive transport modeling in discontinuous-heterogeneous porous media. Comput Geosci 25, 1473–1491, 2021. [2] Salmon, L., Garajeu, M., Lejeunes, S. et al. A thermo-mechanical cohesive zone model for damage and healing in brittle solids. Computation Mechanics, under review [3] Socié, A., Seigneur, N., Bary, B. et al. A fully coupled Hydraulic Mechanical Chemical approach applied to cementitious material damage due to carbonation. npj Mater Degrad 7, 60, 2023.