Electrical conductivity of cement composites incorporating carbon nanofillers for low-grade thermoelectric energy harvesting

Waste heat, causing the urban heat island effect, can be channelized for the generation of low-grade waste heat from pavements and building envelopes with the use of appropriate material. Cement is a key ingredient in modern infrastructure; studies have shown that adding carbon-based nanofillers can turn it into a conductor. In the present study, the inclusion of super-grade graphene (SGG), multi-walled carbon nanotube (MWCNT), and carbon soot-based carbon nanoparticles (CNP) developed a conductive network. Significant improvements in electrical conductivity and formation of conductive pathways are evident from SEM, XRD, Raman spectroscopy, and electrical conductivity analysis. Moreover, the samples exhibited a denser microstructure. The wet method is used to cast the samples. The Four-point probe method is used to evaluate the electrical response. Electrical conductivity of 0.072 S/cm at 2% dose of SGG at 65 °C and 75 °C, 0.28 S/cm at 15% dose of MWCNT at 60 °C, and 0.033 S/cm at 5% CNP at 85 °C is displayed by the respective samples. Percolation threshold, tunnelling, and hopping contribute to a jump in electrical conductivity.