Impedance spectroscopy applied to the study of conductive cements

Abstract

The addition of carbon fibers is the main alternative used for the manufacturing of conductive cements since, at a relative low price, provides a good combination of structural and functional properties. There are many different applications for this type of system, such as the manufacturing of heating elements or anodes for the cathode protection methodology. Most of the studies in this area are focused to the improvement of the dispersion of carbon fibers in the cement matrix. This objective is validated by measures of resistivity. According to this objective, there is no a universal method to verify these measures, but many alternatives can be found on the literature: measures with two or four electrodes, direct or alternating current testing…, impeding comparative analyses. This research offers the impedance methodology, already used for the characterization of common cement pastes without any reinforcements, as an option for the analysis of conductive cements. In this study, different variables are included, such as the type and quantity of dispersants to create a homogeneous mixture. The adjustment of the obtained results, following an equivalent electric model for this kind of systems, allowed us to determine the values of conductivity of different mixtures. With the use of this technique, it is possible to identify the polarization phenomena associated to the carbon fibers, being of interest in order to validate the dispersion of the fibers.