Electrical Properties of Cementitious Systems: Formation Factor Determination and the Influence of Conditioning Procedures

The number of people wanting to use electrical tests to determine the transport properties of concrete has increased with advancements in the portability of hand-held testing devices. Electrical measurements are an attractive test method to quantify transport properties of cement-based materials since they can be performed rapidly. There is a high potential for using these tests in quality control or mixture qualification. However, electrical measurements can be significantly influenced by curing and storage conditions, which can impact the degree of saturation, degree of hydration, sample temperature, and pore solution chemistry. This study proposed a general equation that described the electrical resistivity measurements in cementitious systems and possible methods to account for some of these conditioning-induced changes. It is proposed that these tests are useful in the determination of the formation factor, a numerical quantification that describes the microstructure. A comparison of the formation factor obtained from rapid electrical measurements using the Nernst-Einstein relationship was compared to a migration test with the goal of proposing a curing methodology for rapid electrical tests that allows for the determination of a true transport property.