Sensing properties of CNT-filled cement-based stress sensors

The piezoresistive responses of carbon nanotube (CNT)-filled cement-based sensors are investigated at different compressive stress amplitudes and different loading rates. The correlation between compressive stress and the change in electrical resistance of the sensors is established for the compressive stress in the range from 0 to 10 MPa. Experimental results indicate that the CNT-filled cement-based sensors have stable and reversible piezoresistive responses within the elastic regime. The fabricated sensors achieve a sensitivity of 0.911 k Omega/MPa, a linearity of 7.16%, a repeatability of 1.53% and a hysteresis of 7.24%, and the relationship between input (compressive stress) and output (change in electrical resistance) of the sensors is Delta R = -0.911 sigma. The piezoresistive responses of the sensors are almost free from the effect of loading rate when the loading rate is lower than 0.20 cm/min. If the loading rate exceeds 0.20 cm/min, it will affect the piezoresistive responses of the sensors, and the effect increases with the loading rate.