Factors influencing chloride transport and chloride threshold level for the prediction of service life of concrete structures

Abstract

In this study, the influence of parametric values on the risk of steel corrosion in concrete was quantitatively calculated in terms of the sensitivity to service life of concrete structures subjected chloride attack. Prior to the analysis, a thorough literature review on the chloride threshold level (CTL) for steel corrosion and the rate of chloride transport was performed to define the influencing factors. As a result, it was found that the CTL can be quantitatively represented in the form of total chloride content by weight of cement, reflecting both the corrosiveness and inhibition effect. For chloride transport, diffusion is the main driving force for chloride ions in concrete, although other driving forces such as permeation and sorption simultaneously exist. Finally, the sensitivity analysis of parametric values using the Fick's second law for the prediction of service life of concrete structures due to chloride induced corrosion found that the concrete cover depth is the most influencing to the time to corrosion, followed by the surface chloride concentration, apparent diffusion coefficient and the CTL.