Title: Correlations Between Rapid Chloride Test Results and On-Site Chloride Ingress

Author(s): M. G. Alexander and P. E. Streicher

Publication: Symposium Paper

Volume: 170

Issue:

Appears on pages(s): 473-490

Keywords: Chlorides; diffusion; exposure; portland cement; silica fume; tests.

DOI: 10.14359/6837

Date: 7/1/1997

Abstract:
A modified version of the Dundee rapid chloride test (1) was used to characterise the physical resistance of a range of portland cement and condensed silica fume (CSF) concrete mixtures to chloride ingress. Cubes from these mixtures were placed in submerged, tidal and spray marine exposure zones. The solution to Fick's Second Law was applied to the measured on-site chloride profiles (after 2 years) to obtain apparent diffusion coefficients, Da and surface chloride levels, Cs. The depth of the threshold chloride level, x0.4, was calculated from Da, and Cs. The rapid test results (chloride (C1-) index values) were then correlated with the on-site chloride ingress parameters, Da and x0.4. The best correlation was found between x0.4 and the C1- index values. This can be attributed to the fact that x0.4 is calculated from both Da and Cs, and therefore eliminates a large portion of the scatter arising from the process of chloride profile determinations. The differences in correlations for the different cement types were ascribed to the lower chloride binding capacities of CSF concretes. The need for a suitable chloride binding test, which could be used in conjunction with a rapid chloride test to characterize the potential durability of concrete in ternis of chloride ingress, was identified.