Optimizing Electrical and Mechanical Properties of CAC-Based MWCNT/NCB Conductive Composites at Elevated Temperatures

The development of cementitious conductive composites with enhanced electrical and mechanical properties offers significant potential for multifunctional applications. However, the elevated temperatures' effect on the functional performance of these composites remains unclear. Therefore, the objective of this study was to investigate the effects of elevated temperatures of 200°C, 400°C, and 500°C on electrical and mechanical properties of different mix proportions of calcium aluminate cement (CAC)-based conductive composites incorporating varying contents of multiwalled carbon nanotubes (MWCNTs) and nanocarbon black (NCB). The experimental finding illustrated that the compressive strength of CB1-CB4 composites (MWCNT/NCB contents of 0.25/0.20, 0.50/0.40, 0.75/0.60, and 1.0/0.80) increased after exposure to 200°C. However, the electrical resistivity values of CB3 and CB4 slightly increased compared to that achieved at room temperature. After exposure at 400°C-500°C, the CB3 and CB4 composites with higher concentration maintained stable electrical resistivity values, whereas CB1 and CB2 with lower concentrations showed strength reduction and increased electrical resistivity. It was observed that the CB3 and CB4 composites demonstrated optimal performance, maintaining stable electrical resistivity and mechanical properties under elevated temperature conditions. These findings indicate that the inherent thermal stability of CAC reduces the explosive spalling risk, whereas MWCNT/NCB helps mitigate the adverse effects on electrical resistivity under high temperature conditions. This study offers a novel insight into the optimal concentration potential and highlights the considerable promise of conductive composites for reliable performance under high-temperature conditions.