Numerical simulation of thermo chemo hygro mechanical alkali silica reaction model in concrete at the mesoscale and macroscale Alkali silica reaction causes major problems in concrete structures due to the rapidity of its deformation which leads to the serviceability limit of the structure being reached well before its time. Factors that affect ASR vary greatly including alkali and silica content relative humidity temperature and porosity of the cementitious matrix all these making it a very complex phenomenon to consider explicitly. With this in mind the finite element technique was used to build models and generate expansive pressures and damage propagation due to ASR under the influence of thermo hygrochemoelastic loading. Since ASR initializes in the mesoscopic regions of the concrete the accumulative effects of its expansion escalates onto the macroscale level with the development of web cracking on the concrete surface hence solution of the damage model as well as simulation of the ASR phenomenon at both the macroscale and mesoscale levels have been performed. The macroscale model realizes the effects of ASR expansion as a whole and shows how it develops under the influence of moisture thermal and mechanical loading. Results of the macroscale modeling are smeared throughout the structure and are sufficient to show how damage due to ASR expansion orientates. As opposed to the mesoscale model the heterogeneity of the model shows us how difference in material properties between aggregates and the cementitious matrix facilitates ASR expansion. With both these models the ASR phenomenon under influence of thermo chemo hygro mechanical loading can be better understood.