In this article, we introduce a new micromechanical model for alkali-silica reaction. Our idea was to build a model with the following characteristics. First, the model has to be simple enough to be used to compute damage under loading and chemical attack at the level of each element in a structure code. Second, its parameters must be easy to identify on available alkali-silica reaction lab experiments. We have chosen to model the behavior of concrete containing aggregates such that most of the damage occurs in the cement paste. Using micromechanics and an energy criterion, the model remains analytical except for the minimization of the energy. The parameters were identified on Multon's triaxial experiments and good results were obtained for compressive loadings up to 10 MPa.