Chemo-mechanical modelling of the external sulfate attack in concrete

This paper is focused on the modelling of the mechanical consequences of external sulfate attack in concrete structures under partially or fully saturated conditions. To this purpose a weakly coupled approach is developed: first the moisture content is computed through a simplified diffusion model, then a reactive-diffusion model allows for the computation of the expansive products of the reaction occurring between the aluminates of the cement paste and the incoming sulfate ions, finally the solution of a nonlinear mechanical problem gives the expansion, the stress state and the degradation induced by the reaction. The mechanical problem makes use of a multiphase elasto-damage model, developed in this work and accounting for both chemical and mechanical damage. The model is validated by simulating various experimental tests on concrete specimens subject to external sulfate attack and then applied to the simulation of a reduced scale structure of a tunnel lining.