Toward Performance Specifications for Concrete: Linking Resistivity, RCPT and Diffusion Predictions Using the Formation Factor for Use in Specifications

This paper relates a fundamental material property (the formation factor) with the use of electrical resistivity for acceptance tests of concrete. The paper begins by defining the formation factor. It then relates the formation factor to the rapid chloride permeability test. The formation factor is then related to a predictive model that can be used to determine a corrosion limit state by describing the transport of chloride ions and determining the time required for the onset of depassivation corrosion initiation in a reinforced concrete element. The paper discusses factors that influence electrical resistivity testing along with methods to determine the pore solution conductivity which have been adopted in an AASHTO provisional specification. While the specification will undoubtedly be refined over time and models will require further calibration based on rigorous evaluation and improvement in the coming years, this framework has great potential to directly relate measured concrete properties to the long-term durability performance of concrete structures.