An Elastic Plastic-Damage (EPD) model is developed to model the softening behaviour of the cement-soil admixture based on continuous damage mechanics. The softening behaviour is considered to be characteristic outcome of the material degradation due to damage in material. Material degradation is modelled by reducing progressively the stiffness and yield stress of the material when the damage variable has attained a critical index. The basic equations of the model are derived and presented. A Fortran program for this model has been developed and implemented into a finite element code ABAQUS. In order to evaluate the applicability of this model, several unconfined compression tests are simulated using ABAQUS with this model. The computed results are compared with measured data and good agreement is achieved.