Electrical conductivity of drying cement paste

Abstract

Previous research has shown that electrical measurements can be used to monitor moisture movement inside concrete. The interpretation of these measurements is frequently based on empirical relationships between moisture changes and electrical properties of concrete. As such, these empirical relationships can limit the application of the electrical measurements to a specific material or exposure history. To facilitate the development of a general method that is applicable to a concrete member in service, this paper characterizes the electrical conduction in cement paste subjected to drying (desorption) and moisture absorption. The paper quantifies how the electrical conductivity is dependent on the volume and connectivity of the moisture inside the pores and the conductivity of pore solution. This paper also presents a procedure to quantify the contribution of the surface (solid-pore) conduction on the overall conductivity of the cement paste. The results of this investigation contribute to the development of an embedded relative humidity sensor that can be used to monitor changes in the internal humidity of concrete during its service life.