Electrical Impedance Behaviour of Carbon Fibre Reinforced Cement-Based Sensor Under Wet and Drying Processes

Novel carbon fibre reinforced cement-based sensors offer a potential low-cost and high-performance alternative to externally applied sensors for health monitoring of concrete structures. The frequency dependent electrical properties of cement-based sensors (cement mortar incorpo-rating chopped carbon fibres) were studied under the influence of different fibre and moisture contents. The electrical behaviour was obtained by conducting a series of AC impedance spec-troscopy tests, in the frequency range of 1 Hz – 10 MHz. The effects of fibre content, moisture content and fibre dispersion were quantified in terms of their influence on the electrical conduc-tion and polarization properties. A new model for the assessment of fibre dispersion has been developed. In addition, finite element simulations were used to correlate the experimental results with theoretical outcomes. This work has, for the first time, connected the theoretical and experi-mental aspects of the influence of water phases in the mixes to the impedance response of car-bon fibre reinforced cement-based sensors, as well as quantifying the degree of fibre dispersion by the intrinsic conductivity approach with the consideration of cement heterogeneity. This study will allow for further development and deployment of cement-based sensors for cost-effective and practical monitoring of concrete structures under field conditions