Effect of Copper-Coated Steel Fibers on the Electrical Conductivity of Concrete Under Multiple Influencing Factors

This study investigates the electrical response of concrete containing copper-coated steel fibers (CCSFs), with particular attention to the effects of voltage, which are insufficiently considered in conventional resistivity measurements. An optimized resistivity measurement method was developed to systematically evaluate the effects of CCSF volume fraction, water-to-cement ratio, temperature, and applied voltage on the electrical resistivity of CCSF concrete. The results showed that increasing the CCSF volume fraction from 0% to 3%, the temperature from −20 °C to 80 °C, and the applied voltage from 10 V to 60 V reduced the electrical resistivity by 87.18%, 92.99%, and 80.02%, respectively, whereas increasing the water-to-cement ratio from 0.35 to 0.55 resulted in a smaller reduction of 26.74%. The CCSF content and water-to-cement ratio primarily affected the baseline resistivity, while having limited effects on the normalized temperature response. The applied voltage also affected the absolute resistivity values, and the sensitivity of resistivity to applied voltage increased with increasing CCSF volume fraction. These findings indicate that applied voltage is a key parameter affecting both the electrical response of CCSF concrete and the comparability of resistivity measurements. This study provides experimental evidence for optimizing resistivity testing conditions and evaluating conductive concrete performance under complex environments.