Research on the smart behavior of MCNT grafted CF/cement-based composites

To solve the disadvantages of weak bonding between the carbon fiber (CF) and the cement matrix, as well as the poor dispersion performance of multi-walled carbon nanotubes (MCNT) in cement paste, hydrothermal synthesis and chemical grafting methods were combined to graft MCNT on the surface of CF. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were coupled used to evaluate the grafting efficiency. Four-electrode method and electrochemical impedance spectroscopy (EIS) were applied to assess the electrical property of MCNT grafted CF/cement-based composites. The smart behavior of MCNT grafted CF/cement-based composites were characterized under monotonic and cyclic loading. Results showed that the hydrothermal synthesis method can effectively graft MCNT on the surface of CF, and the grafting ratio as indicated by nitrogen element was 6.78%. The conductivity of MCNT grafted CF/cement-based composites was far superior to that of untreated CF/cement-based composites. Also, the composite with the addition of MCNT grafted CF was more sensitive to the cyclic stress. Therefore, the stress sensitive property of MCNT grafted CF/cement-based composites was significantly improved, compared to its untreated counterpart.