Title:
Effect of Chloride Source Concentration on Chloride Diffusivity in Concrete
Author(s):
Tiewei Zhang and Odd E. Gjørv
Publication:
Materials Journal
Volume:
102
Issue:
5
Appears on pages(s):
295-298
Keywords:
concrete; diffusivity; test
DOI:
10.14359/14707
Date:
9/1/2005
Abstract:
In this paper, the results of an experimental investigation on migration testing of chloride diffusivity in concrete are presented. The results confirm that the effective chloride diffusivity is not a constant but a function of the chloride source concentration. This concentration dependence reflects an important property of the transport behavior of chloride ions in concrete, which is due to various interactions in the concrete system such as ionic interaction, ion-solvent interaction, chloride binding, as well as dielectric properties of the concrete. For the various types of concrete tested, the effective chloride diffusivity at 0.01 M was 10 to 20 times higher than that at 1.0 M chloride source concentration (NaCl). This concentration dependence of the chloride diffusivity is much stronger than what can be predicted by use of the Debye-Hückel theory. For a proper characterization of chloride penetration into concrete, therefore, a complete relationship between chloride diffusivity and chloride source concentration should be established. Also, for the purpose of characterizing the resistance of the concrete against chloride penetration, the intrinsic chloride diffusivity at infinite dilution may be considered as a more basic material parameter.