Research on the conductivity and self-sensing properties of high strength cement-based material with oriented copper-coated steel fibers

In this paper, a cement-based sensor for monitoring the performance of high-strength concrete was prepared by adding 0.5 vol%, 1.0 vol%, 1.5 vol%, and 2.0 vol% copper-coated steel fibers (CCSF) as conductive fillers. The fresh cement-based mixture was poured into a funnel-type fiber alignment device, which used its fluidity of the mixture to achieve an aligned distribution of shear-induce fiber within the cementitious matrix. The analysis results indicate that the cementbased sensor with fiber oriented distribution exhibits enhanced electrical conductivity and lower percolation threshold. In addition, the aligned CCSF in the cement matrix mitigates the impact of temperature on resistivity. The resistivity and temperature of the copper-coated steel fibers cement-based sensors (CSFCS) between 5 degrees C and 70 degrees C conform to the Arrhenius relationship. The specimens with aligned fibers demonstrate greater flexural strength compared to those with randomly distributed fibers. Additionally, they also reflect greater piezoresistive response, including higher sensitivity, better repeatability as well as less hysteresis time. Through the twodimensional cross-section analysis, the angle between CCSF and the cross-section of the fiberaligned specimen is significantly reduced, and the fiber orientation factor and fiber orientation coefficient increased considerably. The funnel device for preparing fiber-reinforced cement-based materials can effectively improve fiber orientation.