Improving electrical and mechanical properties of cement composites by combined addition of carbon black and carbon nanotubes and steel fibers.

A cost-effective cement composite material has been developed for grounding systems, utilizing carbon black, carbon nanotubes, and steel fibers as conductive dopants. The electrical conductivity, mechanical properties, and fluidity of cement composites are investigated, and the synergetic mechanism of multiple conductive dopants in cement composites is revealed based on microscopic means. The results show that the combination of carbon black, carbon nanotubes, and steel fibers facilitates the establishment of efficient conductive networks in cement composites. The addition of 5 % carbon black, 0.3 % carbon nanotubes (by weight of cement), and 0.6 % steel fibers (by volume of composite) reduced the resistivity of the cement composite from 5568 Ω·cm to 310 Ω·cm after 28 days of curing. Then, it decreased to 267 Ω·cm after natural drying in laboratory environment until the 90th day. In addition, the resistivity of cement composites varies less than 5 % in environments ranging from −20°C to 50°C. Furthermore, the compressive and flexural strengths were 30.06 MPa and 6.17 MPa, and the flow diameter was 167 mm, which provided good mechanical strength and workability for conventional engineering applications. This paves an effective way for the further application of cement composites in grounding systems. • Electrically conductive cement composite was developed using carbon black, carbon nanotubes, and steel fibers. • Carbon black, carbon nanotubes, and steel fibers has synergistic combination effect to composite. • The distribution of carbon black, carbon nanotubes, and steel fibers within the cement composites is closely observed. • This combination of conductive dopants facilitates large-scale production of electrically conductive cement composites. [ABSTRACT FROM AUTHOR]