Simplified modelling and numerical simulations of concrete carbonation in unsaturated conditions

ABSTRACT We present in this paper a simplified modelling of cementitious material carbonation in unsaturated conditions, constituting an enhanced version of the modelling presented in (Bary et al., 2004). The main improvements consist in the introduction of kinetics for the calcite formation evolving as a function of the degradation state and in the adoption of carbonation mechanisms different for portlandite and the other hydrates. Moreover, the three coupled equations governing the system are now solved with a mixed finite element method in the Cast3m code. Numerical simulations are carried out and compared in terms of carbonation depth with accelerated test data obtained in the workgroup Concrete Engineering Barriers headed by ANDRA. The confrontation between experimental and numerical results is globally satisfactory; however the determination of pH profiles with the modelling remains an open problem when dealing with accelerated experimental procedures.