Experiment and Micromechanical Modelling on Electrical Conductivity of Curved Carbon Nanotube Reinforced Porous Cement Composites

Carbon nanotube (CNT) reinforced cement composites (CNTRCC) with self-sensing capability have shown great potential for application in structural health monitoring. In this work, a hybrid micromechanical model is developed to predict the overall electrical conductivity of the CNTRCC considering the effects of pores and the orientation and the curved morphology of the CNT. The developed model is validated by comparing theoretical predictions with the experimental results. The results demonstrate that the electrical conductivity of the CNTRCCs considering pores with aspect ratio being 0.01 agree well with the experimental data. The waviness of the CNTs is characterized by different helix angle. A decrease in the helix angle of the CNT results in a decrease in the electrical conductivity of the cement composites. The alignment of the CNTs slightly enhances the electrical conductivity of the CNTRCCs in this direction compared to value for random and uniform distribution of the CNTs. In addition, the potential barrier height plays an essential role in the overall electrical conductivity of the CNTRCCs. An increase in the potential barrier height results in increased percolation threshold for the electrical conductivity of the composites. However, it has limited effects on the electrical conductivity of the CNTRCCs after percolation.