cover cracking of reinforced concrete due to rebar corrosion induced by chloride penetration

 

cracking of concrete cover due to corrosion induced expansion of steel rebar is one of the major causes of the deterioration of reinforced concrete (rc) structures exposed to marine environments and de-icing salts. this paper presents two models that deal with the chloride-induced corrosion and subsequent cracking of concrete cover in rc structures. the former analyses the chloride diffusion within partially saturated concrete. a comprehensive model is developed through the governing equations of moisture, heat and chloride-ion flow. nonlinearity of diffusion coefficients, chloride binding isotherms and convection phenomena are also highlighted. the latter describes the internal cracking around the bar due to expansive pressures as corrosion of the reinforcing bar progresses. once a certain chloride concentration threshold is reached in the area surrounding the bar, oxidation of steel begins and oxide products are generated, which occupy much greater volume than the original steel consumed by corrosion. an embedded cohesive crack model is applied for cracking simulation. both models are incorporated in the same finite element program. the models are chained, though not explicitly coupled, at first instance. comparisons with experimental results are carried out, with reasonably good agreements being obtained. the work is a step forward for the integration of the two traditional phases (initiation and propagation) widely used in the literature and usually analysed separately. the estimation of the service life of the structure needs to evaluate the associated time for each one.