Effect of ZnO nanoparticles on thermoelectric properties of cement composite for waste heat harvesting

Thermoelectric (TE) technology can directly convert thermal energy into electricity for waste heat harvesting and renewable energy production. However, the potential use of TE technology for energy harvesting in civil infrastructure has not been fully explored yet. In this work, the possibility of developing concrete with TE properties to harvest stored heat in concrete structures have been systematically investigated by incorporating zinc oxides (ZnO) based nanoparticles in cement paste. It was found that the addition of ZnO nanoparticles improved the TE properties of cement paste due to the formation of Zn(OH)2 and increased volume of pore solutions in ZnO-cement composites. The results showed that after adding nanoparticles to the mixture, Seebeck coefficient of cement particles was increased to 17% due to a decrease in the amount of hydration reactions. Thermal conductivity was decreased to 9% due to decreased density and crystallinity of materials, and electrical conductivity was increased to 37% compared to that of plain cement paste because of the increased movement of ions. The apparent thermoelectric properties in ZnO-cement composites indicated its potential use for thermal energy harvesting in concrete structures and pavements.