Toward a Specification for Transport Properties of Concrete Based on the Formation Factor of a Sealed Specimen

This paper proposes that the formation factor can be used in performance-based specifications as a fundamental measure of the transport properties of concrete. The formation factor can be measured using a concrete cylinder that is sealed until the age of testing and in either the sealed or fully saturated condition at the time of testing. The proposed method is rapid, easy to perform, fundamentally related to service life models, and is applicable to a wide range of binder compositions. The formation factor is defined herein as the ratio of the electrical resistivity of the bulk sample and the resistivity of the pore solution. The role of temperature, pore solution dilution, and moisture conditioning on the measured results is discussed. The paper then provides a relationship between the formation factor and service life for bridge decks and illustrates how this approach could be used for both a specification and for quality control/quality acceptance. It is recommended that the testing method be standardized, though the performance limits of the formation factor may be dependent on the type and geometry of the structure, the location of the structure, the exposure conditions, and the risk associated with damage to the structure.