Experimental investigations on self-heating capability of cement composites incorporating CNT and CF: Impact of sample size and electrode spacing

The present study investigates the electrical properties and electrical heating capability of cementitious composites incorporated with carbon nanotube (CNT) and carbon fiber (CF) of various sizes and different electrode spacing. Paste and mortar samples were fabricated by incorporating CNTs and CFs of various sizes, and electrodes were inserted at varying distances. The electrical resistivity was determined by measuring the electrical resistance using both the 2-probe and 4-probe methods. A monotonic heating test was conducted for 1 hour to evaluate the heat-generation capability. The results of the test indicated that the maximum temperature decreased with increasing electrode spacing. This observation suggests that the electrical resistance increases as the electrode spacing enlarges, resulting in a decrease in the electrical current when the same voltage is applied, therefore, this reduces the total electrical energy required for heat generation. Furthermore, it was found that there was a linear relationship between electrical power and temperature increase. This trend remained consistent regardless of the type and size of the sample, as well as the electrode spacing.