Research on the electrical conductivity and mechanical properties of copper slag multiphase nano-modified electrically conductive cementitious composite

•Nano-graphite as a functional filler incorporated into concrete can significantly improve its electrical conductivity. Meanwhile, the proper amount of nano-graphite addition can also increase its mechanical strength.•The addition of copper slag improved the mechanical properties and electrical conductivity of ECCC.•The chemical activation improved the reactivity of the volcanic ash in the fly ash–cement system. The ultrasonic vibration process facilitates the uniform distribution of nano-graphite.•Combined activation is the best method to improve mechanical properties and electrical conductivity, possessing the advantages of chemical and ultrasonic activation.