PREDICTION OF TIME TO CORROSION INITIATION OF STEEL IN MARINE CONCRETE STRUCTURES PART I: SENSITIVITY OF CORROSION INITIATION TIME TO CHLORIDE DIFFUSION COEFICIENT AND CONCRETE COVER DEPTH

Abstract

In this paper, a diffusion based model has been developed to predict time to corrosion initiation of steel in concrete due to chloride. Sensitivity analysis of the model was carried out on input parameters which are chloride diffusivity in concrete and concrete cover depth. It is show that the sensitivity of time to corrosion initiation to chloride diffusion coefficient and concrete cover depth is independent of the ratio of surface chloride content and chloride threchold level. It is indicated that the concrete cover depth has a greater impact on time to corrosion initiation that does the chloride diffusion coefficient. A decrease in th chloride diffusion coefficients is considered as effective way of extending time to corrosion initiation. A decrease of  50% in the chloride diffusion coefficient will lead to an increase of 100% in time to corrosion initiation. However, an increase of 50% in concrete cover depth will lead to an increase in time corrosion initiation by 125%.