Self-sensing performance of cementitious composites with electrostatic self-assembly carbon nanotube/titanium dioxide

Carbon nanotube/titanium dioxide (CNT/TiO₂) composite fillers were obtained using electrostatic self-assembly technology with combining conductive carbon nanotube (CNT) and microscale titanium dioxide (TiO₂) based on excluded volume effect. And then, cementitious composites with electrostatic self-assembly CNT/TiO₂ was used to develop cementitious composites with excellent self-sensing performance. The electrical properties of cementitious composites with electrostatic self-assembly CNT/TiO₂ were investigated. At the same time, the effects of different environmental conditions on self-sensing performance also were studied including loading amplitudes, loading rates and water content. Additionally, modification mechanisms of electrostatic self-assembly CNT/TiO₂ composite fillers on electrical and self-sensing performance of cementitious composites were also analyzed. Finally, the effect of different environmental factors on self-sensing performance were compared by radar chart. The results show that electrical resistivity of cementitious composites with electrostatic self-assembly CNT/TiO₂ is decreases by 99.8% when the volume content of CNT is 2.40%. Its maximum fractional change in resistivity is up to 49.23% under cyclic compression. Meanwhile, its stress and strain sensitivity can reach 8.21%/MPa and 812, respectively. The cementitious composites with electrostatic self-assembly CNT/TiO₂ present excellent self-sensing performance under different loading amplitudes, loading rates and water content. The sensitivities decrease with increasing of the loading amplitudes but increase with increasing of loading rates. In addition, the maximum fractional change in resistivity, stress and strain sensitivities increase with the decreasing of the water content. The maximum fractional change in resistivity, stress and strain sensitivities of cementitious composites with electrostatic self-assembly CNT/TiO₂ can reach 74.36%, 12.39%/MPa and 1350 under full drying at 50℃, respectively. The radar chart demonstrates that the important orders of the different environmental factors effect on self-sensing performance is water content, loading amplitudes and loading rates.