Physical Origin of Temperature Induced Activation Energy Switching in Electrically Conductive Cement

Electrically conductive cement (CEMe), enabled by percolative networks of conductive fillers, presents a promising future for multifunctional cementitious composites in next-generation sustainable infrastructure. However, the mechanisms governing temperature-dependent charge transport, particularly the temperature-induced switching of Arrhenius activation energy, remain poorly understood. This study provides a rigorous investigation into the physical origin of variable activation energy behaviour in CEMe across different percolation regimes, a key factor for ensuring reliable multifunctional performance. It is demonstrated that activation energy switching arises from structural degradation within the biphasic conduction architecture: ionic transport through liquid-filled connected pore network and electronic conduction via conductive carbon fibre network. In contrast, the intrinsic non-Arrhenius behaviour of the pore solution and the Arrhenius behaviour of the carbon fibre have negligible influence on the overall activation energy switching behaviour. For the first time, Meyer–Neldel Rule (MNR) is observed in CEMe, attributed to the stable intrinsic conductivity (≈0.046 S m−1) of calcium silicate hydrate (C─S─H) gel across the temperature range of 5–90 °C and carbon fibre contents of 0–1.5 vol%. These findings advance the fundamental understanding of charge transport in CEMe and biphasic conducting materials systems, establishing a robust scientific basis for designing intelligent, multifunctional materials that adapt to dynamic environments.