Concrete resistivity values for chloride resistance classes.

The electrical resistivity of concrete represents its porosity and tortuosity. For years, the use of this parameter has been proposed due to its ease of measurement (non-destructive) on the same specimen used for compressive strength testing and both as a corrosion indicator and because of its equivalence with the chloride diffusion coefficient. The latest version of Eurocode 2 (EC2) for concrete introduced the Exposure Resistance Classes (ERCs) concept, which allows concrete to be classified by its diffusion coefficient in a standardized test or by its resistance to carbonation. In this work, a simplified equivalence between resistivity and the apparent chloride diffusion coefficient has been applied to obtain the ERC’s table based on resistivity. The model for calculating cover requirements has also been simplified, requiring only the resistivity, aging exponent and exposure factor.