Piezoresistivity of three dimensional graphene-carbon nanotubes/cement paste

In order to explore the piezoresistivity of three dimensional graphene-carbon nanotubes (G-CNTs)/cement paste, the four-electrode method was used to study the resistivity change of the G-CNTs/cement paste under load. The influence of G-CNTs content, loading amplitude, loading speed and constant load on the resistivity change was analyzed. The results show that the resistivity decreases first and then tends to stabilize with the increase of the G-CNTs content. When the G-CNTs content increases from 0.2wt% to 1.6wt%, the resistivity decreases by 51.8%. The resistivity is negatively correlated with temperature. When the G-CNTs content is higher than 0.8wt%, the piezoresistivity of the cement paste is significantly improved, and the rate of change in resistivity has an obvious corresponding relationship with the stress-strain. The stress sensitivity coefficient and the strain sensitivity coefficient of the specimens with 1.2wt% G-CNTs are 2.3%/MPa and 291, respectively. The amplitude of the rate of change in resistivity of G-CNTs/cement paste increases as the loading amplitude increasing. The rate of change in resistivity curve corresponding to the stress-strain changes under different loading speeds and constant load exhibits good piezoresistivity.