The use of bulk diffusion tests to establish time-dependent concrete chloride diffusion coefficients

The proper determination of chloride diffusion values, including how they change with time, is important for service life modelling. Currently, there are two major approaches for using chloride diffusion coefficients to predict the service life of structures. The average diffusion coefficient or the instantaneous diffusion coefficient can be used. Using instantaneous diffusion coefficients is a more flexible technique, but requires a more advanced evaluation of bulk diffusion test results to establish material parameters. This paper describes an analytical procedure for determining the instantaneous chloride diffusion value as a function of time for a concrete using data from bulk diffusion tests. The importance of interpreting the data correctly is illustrated with simulated bulk diffusion test data, generated using a finite-difference model for diffusion. In addition, the application of this procedure for evaluating diffusion values is illustrated with experimental data. (C) 2003 Elsevier Science Ltd. All rights reserved.