Measurement and modelling of conduction in carbon fibre-cement composites

The present work investigated the conductive performance of carbon fibre-reinforced cement under different frequencies of alternating current, involving fibre fractions both below and above the percolation threshold. The electrical conductivity of carbon fibre-reinforced cement changes according to the frequency of the alternating current. Tests on samples with fibre fractions below the percolation threshold show similar change pattern in the impedance–frequency curve. The trend of decreasing impedance with increasing frequency becomes less marked as the carbon fibre content increases. An equivalent circuit model of carbon fibre-reinforced cement has been proposed to describe the electrical performance based upon the experimental results. Moreover, using linear regression the correlation coefficients were analysed to show the rationality of the model. Results indicate that the resistance under alternating current is lower than that under direct current. The capacitance increases with increasing fibre content.