Study on electrical conductivity model of concrete based on multiphase composite theory

Abstract

Leakage detection is one of the core issues to ensure the safe operation of hydraulic buildings. Due to the high electrical conductivity of water, the change of water content at the leakage point will lead to a drastic change of conductivity, so the spatial distribution and structural characteristics of hydraulic concrete defects can be preliminarily explored by establishing a mathematical model of conductivity and water content, and taking the localized water content of the concrete as an indicator for identifying the leakage point. In this study, based on the multiphase composite theory, concrete is considered as a three-phase composite medium consisting of "solid-water-gas", aiming to establish a conductivity model related to porosity and water content in order to analyse the spatial distribution and movement of water in concrete. By conducting concrete conductivity experiments under varying aggregate volume fractions, porosity, and water content, model parameters were defined. The results indicate that the new model can predict conductivity within a larger range of porosity and water content, with errors not exceeding ± 9 % compared to experimental data. The mathematical relationship established by the model between conductivity and water content facilitates the identification of regions with anomalous water content, thereby providing a preliminary delineation of potential leakage points and approximate extent. This model offers theoretical guidance for non-destructive electrical detection of leakage areas in concrete.