Improving electrical and piezoresistive properties of cement-based composites by combined addition of nano carbon black and nickel nanofiber

This article aims to improve the electrical and piezoresistive properties of cement-based composites by the combined addition of nano carbon black (NCB) and nickel nanofiber (NiNF). The cement-based composites with NCB/NiNF and NCB were fabricated. The distribution of NCB and NiNF in cement matrix was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX). The effects of several factors, including NCB content, temperature and humidity on the electrical conductivity of cement-based composites were examined by four-electrode method. Besides, the piezoresistive properties of composites under cyclic loading and monotonic loading were explored. Experimental results show that two types of cement-based composites exhibit visible percolation phenomenon. Hybrid use of NCB and NiNF can obviously degrade the resistivity of composites. NCB/NiNF cement-based composites have better temperature sensitivity and humidity adaptability. Under cyclic loading, NCB/NiNF cement-based composites are superior to NCB cement-based composites in linearity and repeatability. Cement-based composites hybrid with NCB and NiNF show more stable compression load response under monotonic loading. In addition, the constitutive relation between stress and fractional change in resistivity (FCR) is proposed, which can be used as the calibration curve for cement-based sensor. •Nano carbon black and nickel nanofiber can improve the self-sensing properties.•The state of nano carbon black and nickel nanofiber in cement matrix is observed.•The resistivity is measured by the four-electrode method.•The relation between stress and fractional change in resistivity is proposed.