How can Electrical resistivity be used to determine Chloride Diffusion Coefficient?

Electrical resistivity has been employed as a quality control method to evaluate chloride permeability in concrete. Recently, though, research has shown that there is an excellent correlation between electrical resistivity of concrete (4 probe wenner) and chloride diffusion coefficient of concrete, which can directly be used in predicting the service life of an element*.

regression

These research projects were parts of a bigger plan to move the electrical resistivity method from a qualitative quality control method to a quantitative method for service life prediction.
Since the 2000s, the Florida Department of Transportation (FDOT) has employed a nondestructive method by measuring the electrical resistivity of water-saturated concrete to evaluate the chloride permeability.

However, Australian own “Recommended Practice; Concrete Durability Series Z7/07; Performance Tests to Assess Durability”, published by Concrete Institute of Australia, claims that although the method is widely used in North America to indicate resistance to chloride ion penetration, it may only be used to monitor chloride penetration resistance if calibrated against chloride ion diffusion tests on the same concrete. Additionally, 4 probe Wenner surface resistivity test can easily detect changes in concrete composition.

Reference:
* “Determination of Chloride Diffusion Coefficients in Concrete by Electrical Resistivity Method”, by Yanbo Liu, Francisco J. Presuel-Moreno, and Mario A. Paredes; 2015 ACI Material Journal