Heating Performance and Flexural Strength of Steel Fiber–Carbon Nanotube Cement Composites for Black Ice Prevention

Cementitious composites incorporating multi-walled carbon nanotubes (MWCNTs), known for their superior mechanical, electrical, and thermal properties, present significant potential for multifunctional infrastructure applications. This study quantitatively evaluates the heat generation behavior, electrical resistivity, and flexural performance of hybrid cementitious composites reinforced with MWCNTs and steel fibers. A total of 72 specimens were tested following ASTM and KS standards, considering MWCNT concentrations of 0.0, 0.5, and 1.0 wt% and a steel fiber content of 2.0 vol%. The results revealed that increasing MWCNT concentration markedly enhanced heat generation, reaching a maximum temperature rise of 80.1 °C, while electrical resistance decreased by over 99% compared with basic mortar. The inclusion of steel fibers slightly reduced heat generation but improved flexural strength by up to twofold due to fiber bridging and crack control. Microstructural analyses (FE-SEM, XRD, and TGA) confirmed the formation of continuous CNT networks that facilitated electron transport and improved matrix densification. Although the findings are based on laboratory-scale specimens, the combined use of MWCNTs and steel fibers offers a promising pathway for developing self-heating, mechanically enhanced cementitious materials applicable to black-ice prevention and durable pavement systems.