Time dependent chloride diffusion coefficient : field studies of concrete exposed to marine environment in Norway

Abstract

The apparent chloride diffusion coefficient derived by evaluating chloride profiles using Fick’s 2nd law of diffusion is found to be time dependent and may decrease considerably with increasing age of the concrete. In service life predictions of marine structures this time dependency of the diffusion coefficient is taken into account by an age factor. However, reliable data for this age factor are limited. Field studies on concrete exposed to marine environment have been conducted in Norway over the last three decades in order to investigate the time dependency of the apparent chloride diffusion coefficient. This paper presents results from some of these field studies. To illustrate the sensitivity of the age factor in service life calculations, a numerical study is performed using a probabilistic approach.