Analysis on durability of reinforced concrete bridges in maritime environment

The paper provides a review of durability issues of the Adriatic large concrete arch bridges built in two periods: in the 1960’s and 1970’s and at the last turn of the century. Inadequate attention to durability issues in combination with very aggressive maritime environment has led to rapid deterioration of the structures caused by corrosion of reinforcement steel in concrete. In order to develop consistent maintenance policy that would provide efficient and effective management of bridges in maritime environment, it is necessary to determine remaining service life of the structures. In this purpose the coupled 3D chemo- hygro-thermo mechanical model is developed and implemented into FE code. The applications of the model are illustrated on three numerical examples. The numerical results are in good agreement with the available experimental data leading to the conclusion that the model is able to realistically predict service life of reinforced concrete structures exposed to chlorides and mechanical damage results. In service performance of the Adriatic large concrete arch bridges shown and numerical analysis confirmed the following: (i) cracks in concrete cover, which are the consequences of mistakes in conceptual design as well as errors and negligence on site, significantly reduces depassivation time of reinforcement bar ; (ii) corrosion rate is much higher in poor than in good quality concrete ; (iii) the maximal numerical results of corrosion rate, achieved at critical water saturation, are within the limits for concrete in splash zone, as one of the most critical environment for corrosion of steel in concrete, (iv) corrosion induced cracks significantly reduce pull-out capacity of reinforcement.