Simulation of Chloride Migration in Compression-Induced Damage in Concrete

The ingress of chloride ions in a harsh chloride environment leads to the corrosion of reinforcing steel bars and reduction in the service life of concrete structures. Prediction of the service life of chloride-exposed concrete structures is strongly dependent on chloride diffusion coefficient, which in turn is influenced by several factors including materials and environmental parameters, binding of chloride ions to the solid phase of concrete, and the stresses caused by external load acting on the structure. The diffusion of chloride in concrete is increased significantly by damage associated with load-induced stress, which, if not taken into account, can lead to erroneous prediction of the service life. This paper investigates the impact of compressive stress-induced damage on chloride transport in concrete. An experimental investigation involving non-steady-state migration test as per NT BUILD 492 was carried out on unloaded concrete specimens damaged under axial compressive load. Numerical simulation of the rapid chloride-migration test using multiphysics finite element software is presented in which a phenomenological damage model and a chloride-binding isotherm coupled with Nernst-Planck equation is used to evaluate chloride migration in the damaged concrete specimens.