Tailoring sensing properties of smart cementitious composites based on excluded volume theory and electrostatic self-assembly
Liqing Zhang, Qiaofeng Zheng, Xufeng Dong, Xun Yu, Yanlei Wang, Baoguo Han
Abstract
The excluded volume effect is the reduction in free volume of a matrix filled by secondary fillers, which can enhance the conductive network of carbon nanotubes (CNTs) composites and work effectively with microscale secondary fillers. Besides, the electrostatic self-assembly method has been proved effective for dispersing CNTs. Therefore, this study aims to assemble microscale TiO 2 with CNTs to develop smart cementitious composites, in an effort to tailor the sensing properties based on the excluded volume theory and electrostatic self-assembly method. The results show the composites with CNT/TiO 2 have a high sensitivity, a wide stress/strain monitoring range, and acceptable mechanical properties. In elastic state, the strain sensitivity of cementitious composites can reach 317. The composite can monitor the compressive stress from 0 to 80.7 MPa, with the maximum fractional change in resistivity as high as 84.09%. Furthermore, due to its low water absorption property, the CNT/TiO 2 filler exhibits little negative effect on the mechanical properties of cementitious materials with best piezoelectric performance.