Analysis of the microstructure of carbon fibre reinforced cement pastes by impedance spectroscopy

The purpose of this study is the identification of the changes produced in cementitious matrices by the incorporation of carbon fibres. The characterization was completed by impedance spectroscopy and mercury intrusion porosimetry on specimens with increasing amounts of carbon fibres. An increased porosity for the higher fibre contents was revealed. The impedance analysis, based on the model used for unreinforced specimens, showed a poor dispersion, even for the lowest contents, and the modifications produced by the fibres could be qualitatively recognized. This preliminary analysis allowed the definition of an innovative electrical equivalent model, which includes the polarization at the fibre surface. The role of two dispersing techniques could be validated, since variations assigned to the fibre active surface available for polarization were detected. Impedance is presented as a promising methodology for the study of the microstructure in carbon fibre reinforced cement composites. (C) 2020 Elsevier Ltd. All rights reserved.