A new model for the electrical conductivity of cement-based material by considering pore size distribution

Abstract

Electrical conductivity is one of the most important indicators of the durability, impermeability and frost resistance of cement-based materials (CBMs). It is also a main performance parameter for some special CBMs such as insulating concrete and electrically conductive concrete. The aim of this study was to examine the relationship between electrical conductivity and saturation degree of CBMs more deeply by considering the pore size distribution (PSD), which is described in a new way. The distribution of the pore solution (the main conducting medium) in CBMs was analysed by considering the PSD function, the Kelvin equation and theories of capillary and surface adsorption. According to the pore solution distribution and conductivity theory, a conducting tube network model was established. The curves obtained by the proposed model were found to fit the experimental data well. The conducting tube network model was then used to analyse the factors influencing the electrical conductivity of CBMs. The conclusions obtained from this study were that the electrical conductivity of CBMs varies with the relative ratio of large and small pores and the mean value and standard deviation of large pores, and that the electrical conductivity of CBMs is proportional to the pore solution conductivity and porosity of the CBM.