Moisture-dependent piezoresistive responses of CNT-embedded cementitious composites

This study experimentally investigated the effect of moisture content on the piezoresistive responses of carbon nanotube (CNT)-embedded cementitious composites. In an experiment, changes in electrical resistance were measured under repeated application of sinusoidal compressive forces to the CNT-embedded cementitious composite specimens with different moisture contents. Experimental results revealed that as the internal relative humidity (IRH) of the specimens decreased, the piezoresistive responses, such as initial electrical resistivity, amplitude of electrical resistivity change, and piezoresistive sensitivity, increased significantly. The rate of change in piezoresistive sensitivity resulting from IRH variation increased nonlinearly with IRH drop, and rapid increase was observed when IRH drop was more than 35%, which was related to evaporation of surface multilayer adsorbed water in the specimens. The results of this study can be used for improving quantitative evaluation of the piezoresistive responses of CNT-embedded cementitious composites with variable moisture content, in the long term.