Conductivity and conducting stability of copper-coated carbon-fiber-reinforced cement-based composite

Conductivity and especially conducting stability are crucial factors in engineering applications of conductive cement-based composites. The use of a plating method to prepare copper-coated carbon fiber (CCF) allows for the carbon fiber resistivity to be reduced significantly with an increasing plating thickness. We studied the influence of plating thickness, CCF content, age, and moisture content on the resistivity of CCF-reinforced cement-cased composites (CCFRC) and the conductivity mechanism of the CCFRC, and the influence of plating thickness on the CCFRC conductivity and conducting stability were determined. The experimental results indicate that the CCFRC resistivity decreased significantly with an increasing plating thickness from 1.1 to 2.6 mu m, and the mechanical properties of the CCFRC improved. When the plating thickness increased from 0 to 2.6 mu m, the percolation threshold decreased from 0.6% to 0.4%, the variation coefficient of the 28-day resistivity decreased from 10.97% to 5.12%, and the resistivity ratio between 180 days and 28 days decreased from 2.74 to 1.54. The roughness and wettability of the CCF surface improved with an increase in plating thickness, and the CCF dispersion improved significantly. The CCF overlapped more easily to form a conductive network due to the increasing dispersion. The tunnel effect was enhanced with an increase in plating thickness because the number of free electron increased, and thus, the percolation threshold decreased. Meanwhile, the conductivity, and especially the conducting stability, were improved dramatically with the increasing plating thickness. According to the CCFRC impedance spectrum, the conducting stability was improved significantly with an increase in plating thickness.