Popcorn Effect-inspired Self-propagating Formation of High-conductivity Cement Composite for Multifunctional Applications.

The surge in modern civil technologies demands a transformation in cement composites to surpass traditional roles and integrate smart functionalities. In this regard, enhancing the electrical conductivity of cement composites is a critical challenge. This study introduces a novel strategy for the self-propagating formation of expandable graphite-based high-conductivity cement composites through a simple thermal treatment with 3 wt.% expandable graphite and 1 wt.%carbon fiber as conductive fillers. Inspired by the popcorn effect, this method leverages the rapid expansion of graphite at high temperatures, promoting contact between conductive fillers and forming new conductive networks. The obtained composites demonstrate a remarkable reduction of 60% in electrical resistance after heat treatment compared to the electrical resistance of standard cement composites, and the enhancing mechanisms is explored. The conductive properties endow the material with excellent electrothermal (>100 °C at 10 V), electrothermochromic (response time of 2 s), and electromagnetic interference shielding (42 dB at 12.4 GHz) performance. This innovative approach provides vast opportunities for developing smart infrastructure with enhanced electrical properties, regarded as a promising candidate for promoting next-generation buildings and infrastructures.