Strength, toughness and interface modification of graphene oxide grafted carbon fiber modified concrete

Graphene oxide grafted carbon fiber (CF-GO) is prepared by "grafting to" chemical graft method. The elements and chemical bonds on the surface of CF-GO are characterized by XPS test, which confirms the successful preparation of CF-GO, and the monofilament tensile strength of CF-GO is tested. The dispersion effect of CF-GO under different dispersion methods is compared, and CF-GO modified concrete (CF-GOMC) is prepared. The strength and toughness of CF-GOMC are tested and compared with those of carbon fiber modified concrete. In addition, the modification mechanism of CF-GO on fiber/concrete matrix interface is analyzed by SEM-EDS test. The results show that the monofilament tensile strength of CF-GO increases by 22.22% compared with that of carbon fiber. When dispersing with high-efficiency water reducer combined with ultrasonic wave, the dispersion effect of CF-GO is the best, the resistivity of CF-GOMC is the minimum, and the strength is the maximum. CF-GO can improve the strength and toughness of concrete, and its improvement effect is better than carbon fiber. The optimal contents of CF-GO and carbon fiber are 0.3% and 0.2% respectively. Graphene oxide on the surface of CF-GO enhances the fiber/concrete matrix interface physically and chemically by improving the mechanical interlocking force between CF-GO and concrete matrix and promoting the formation of hydration products on the surface of CF-GO. Moreover, the content of C-S-H crystal at the CF-GO/concrete matrix interface increases.