Experimental study on effect of temperature and moisture on piezoresistive effect of carbon nanotube concrete

Abstract

Carbon nanotube (CNT) reinforced cement based composite materials can be used as self-sensing sensors for intelligent monitoring of concrete structures. In practical engineering, concrete structures are affected and restricted by various environmental factors. Therefore, this paper conducted experimental research on the influencing factors of the piezoresistive effect of CNT concrete. The main influencing factors selected include CNT concentration (0 wt.%–0.5 wt.%), moisture content (immersion time of 0 min–120 min), and temperature (20 °C–60 °C). The experimental results show that the specimen with a CNT concentration of 0.5 wt.% has a higher stress sensitivity (SES), and the change in resistivity shows good stability and repeatability under cyclic stress. The resistivity decreases with prolongation of immersion time, and the SES increases first and then decreases, reaching a peak at 30 min of immersion. When the temperature increases from 20 °C to 60 °C, the resistivity decreases. The influence of temperature on dry and wet specimens is different. In the moisture state, the fraction change in resistivity and SES always decreased. In the dry state, as the temperature increases, the SES first increases and then decreases, with the maximum value occurring at 30 °C.