Strengthening and toughening behaviors and dynamic constitutive model of carbon-based hierarchical fiber modified concrete: Cross-scale synergistic effects of carbon nanotubes and carbon fiber

Abstract

Considering the synergistic effects (filling, activating, bridging, anti-cracking, and interface-optimizing) of combined carbon fiber and carbon nanotubes, the strategy of using carbon nanotubes-carbon fiber cross-scale reinforcement (CNTs-CF) to enhance concrete was proposed. The strengthening and toughening behaviors of CNTs-CF modified concrete (CCMC) were experimentally investigated. The results showed that CCMC had good crushing resistance capacity, and the addition of an appropriate amount of CNTs-CF was conducive to alleviating the brittle failure characteristics of concrete materials. Compared with ordinary concrete, the static and dynamic strength properties and toughness indexes of CCMC were greatly improved. When the volume content of CNTs-CF in concrete was 0.3%, CCMC showed the most superior strengthening and toughening behaviors. The hierarchical assembly and synergistic effect of carbon fiber and carbon nanotubes realized the combination of high strength and high toughness of concrete materials. The proposed rate-dependent constitutive model with damage based on Weibull statistical theory in this study can be used to accurately predict the dynamic compressive stress-strain relationship curve of concrete under different fiber content and strain rate.