COMPUTATIONAL MODELLING OF CHLORIDE ION TRANSPORT IN REINFORCED CONCRETE

Exposure to a saline environment is a major threat with respect to the durability of reinforced concrete structures. The chloride ions, which are present in seawater and de-icing salts, are able to penetrate the concrete to the depth of the reinforcement, where they eventually trigger a pitting corrosion process. The assessment of a corrosion-free service life of concrete structures is of paramount economic interest. However, the modelling of the ingress of chloride ions is complicated due to various influencing factors and transport mechanisms. Here a computational model for chloride ion transport through a porous material is presented. Chloride ion transport in reinforced concrete is modelled by focusing on centimetre-level and setting up three coupled equations for heat, moisture and chloride ion transport respectively. The model is handled computationally by discretising in space according to the finite element method and discretising in time according to the finite difference method. Stationary and transient, linear and non-linear, homogeneous or heterogeneous calculations can be performed. Moisture migration according to Bazant and Roelfstra has been implemented and Saetta's concept of chloride transport is followed. This is illustrated with a numerical example, which focuses on the coupling between chloride ion and moisture flow.

• INTRODUCTION

• THREE COUPLED BALANCES

• SUBSTITUTED MODELS

• NUMERICAL EXAMPLE

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES