Enhancement of the piezoresistive and mechanical properties of cement-based composites filled with CNTs/GO and nano-SiO₂ sprayed steel fibers

Steel fibers (SFs) are one of the most suitable functional fillers for the preparation of large-volume self-sensing concrete due to their good dispersion and toughness, whereas it has poor sensing performance. In this paper, a CNTs/GO-sprayed method was proposed to modify the surface of SFs as well as nano-SiO₂ was used to enhance the interface between SFs and matrix, in which the content of carbon-based materials could be precisely quantified. Then, self-sensing performance, pull-out test, and macro stable mechanical performance were carried out. The results revealed that the specimens filled with straight smooth (SS) SFs sprayed with GO and nano-SiO₂ had the highest self-sensing ability. Compared to unmodified SFs, the degree of improvement reached 225% and 270% within 0 ∼ 60 kN and 0 ∼ 90 kN, respectively, and the addition of nano-SiO₂ increased the pull-out energy. In addition, the macro mechanical properties of the specimens filled with the modified SS SFs were better than that of the hooked end (HE) SFs.