Electrical Properties of Strain-Hardening Cement Composite (SHCC) with Multi-Walled Carbon Nanotubes Exposed to High temperature up to 900 °C

Abstract

Cement-based sensors mixed with carbon nanotube (CNTs) for structural health monitoring were studied to detect changes in electrical resistance under the influence of temperature, pressure, and mass. Strain-hardening concrete composite mixed with CNT was heated to 900 °C to analyze the electrical resistance characteristics at high temperatures. The temperature and electrical resistance were measured using a thermocouple and an LCR meter during the heating and cooling processes. The resistance trend changed between 300 and 400 °C during the heating process, after which the resistance change rate with respect to temperature decreased. At 700 °C or higher, the resistance became larger as the initial resistance increases. In the cooling process, when the temperature dropped below 700 °C, a rapid change in resistance was observed, and the resistance began to drop sharply between 500 °C and 600 °C to become negative resistance. Following this, self-sensing ability decreased owing to changes in the resistance with respect to temperature. Multi-walled carbon nanotubes could not be distinguished by scanning electron microscope imaging after heating.