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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.

The present study systematically investigated the influence of varied conductive filler contents on the negative/positive temperature coefficient (NTC/PTC) effects in cement-based self-heating composites. Different composite formulations containing varying proportions of carbon nanotubes (CNT) and carbon fiber (CF) were prepared and subjected to self-heating tests at different input voltages. Analysis of temperature and electrical conductivity data obtained during the tests elucidated the NTC/PTC effects. Additionally, diverse analytical techniques were employed to characterize the physicochemical properties of the samples. Results indicated a correlation between NTC and PTC effects and thermal expansion as well as variations in electrical resistivity with increasing temperature. Moreover, a specific temperature and electrical resistivity range is identified where the NTC effect transitions to the PTC effect, a transition range influenced by the conductive filler content. Enhanced heat-generation accelerated the PTC effect by inducing structural alterations in the sample's physicochemical composition.

This study proposes a novel method of fabricating nanohybrid particles composed of carbon nanotubes and carbonyl iron powder (CNT@CIP), which are then embedded in a polymer for use as electromagnetic interference (EMI) shielding. First, a method of fabricating CNT@CIP nanohybrid particles is introduced, and their formation is verified using characterization tools such as zeta potential analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy. Then, the CNT@CIP nanohybrid particles are incorporated into a polymeric matrix. The electrical conductivity and EMI shielding capability of the resulting composites are systematically investigated. According to the experimental results, it can be found that the electrical conductivity and EMI shielding effectiveness increase with increasing of CNT@CIP nanohybrid particles contents. In addition, they are improved by the alignment of the CNT@CIP hybrid particles caused by the magnetization curing, reducing the amount of electrically conductive fillers required. Consequently, utilization of CNT@CIP nanohybrid particles and magnetization curing can greatly improve the electrical conductivity and EMI shielding capability, showing their potential as EMI shielding composites in various practical applications.