Cracks, caused by shrinkage or external loading, reduce the durability of concrete structures as aggressive substances can easily enter in the capillary network of the cementitious matrix. Natural 'autogenous' healing ability of concrete by further hydration or precipitation has been studied experimentally for many years. Autogenous healing of concrete by further hydration of residual unhydrated cement particles is triggered by the ingress of water and/or moisture into the crack and leads to a partial recovery of mechanical properties (Young's modulus, tensile strength,...). However, theoretical studies and computer simulations still need to be developed in order to explain macroscopic behaviour of healed specimens and conditions of occurrence of the self-healing phenomenon. In this study, a hydro-chemo-mechanical model was developed to simulate autogenous healing by further hydration. Firstly, a simulation of a three-point-bending test was performed to represent the initial damaged state before the self-healing process. The volume fraction of the residual cement clinkers at this moment has been calculated with a hydration model. Then, the self-healing phenomenon of concrete beams immersed into water was modelled based on micro-mechanical observations. The diffusion process has been simulated using the Fick's law in order to describe the ingress of water into concrete. The hydration model, based on the Arrhenius law, is then used to simulate the chemical reactions between residual clinkers and water. The mechanical properties of the new formed hydrates are therefore evaluated in order to describe the partial recovery of mechanical properties of healed concrete.