Consistent return mapping algorithm for chemoplastic constitutive laws with internal couplings

This paper discusses the algorithmic formulation of chemoplastic models with internal couplings. Developed within the framework of closed reactive porous continua, chemoplasticity allows for the introduction of the kinetics of a chemical reaction directly at the macro-level of material description. The resulting couplings (chemoelastic, chemoplastic) slightly complicate the integration of stresses at the material level, leading to chemoplastic hardening =softening. In this paper, the numerical integration of stresses for this type of constitutive laws with chemomechanical (internal) couplings is presented. Based on the de nition of return mapping algorithms for standard plasticity, a closest-point projection algorithm is developed, which preserves the quadratic rate of convergence of the Newton{Raphson iterative scheme. Examples are presented with an increasing degree of complexity: perfectly plastic behaviour with chemical hardening for concrete at early ages, coupled creep-plastic behaviour, plastic behaviour with combined viscoplastic hardening=softening for concrete in high-rate dynamics