Using a Saturation Function to Interpret the Electrical Properties of Partially Saturated Concrete

Electrical properties are frequently measured in the concrete construction industry as a part of mixture qualification and quality-control testing. Whereas there are several factors that influence the electrical response of concrete, one of the most important factors is its degree of saturation. Although current standard tests rely on the concrete's being saturated, this can be difficult to accomplish, is time-consuming, and can artificially increase the degree of hydration of the test sample in comparison with that of concrete in field structures (when the test samples are stored in water). Although some studies have measured the electrical response of concrete for samples with different moisture content (i.e.,stored at different relative humidities), a single expression has not been proposed that predicts how drying changes the electrical response. This paper suggests that a saturation function should be considered as a possible method to account and to correct for less than complete saturation in concrete. This function would provide one term that accounts for changes in pore fluid volume, pore solution concentration, and pore fluid connectivity. Although preliminary, this approach has several potential benefits: (1)it could enable testing of partially saturated concrete, thus saving time; (2)it could be used to predict properties under different exposure conditions; (3)it may facilitate more comprehensive service-life models; and (4)it may enable a wider use of embedded sensor technology. (C) 2013 American Society of Civil Engineers.