Thermoelectric properties of the main species present in Portland cement pastes

Several experimental studies have been conducted on the thermoelectric properties of cementitious materials, but a detailed inspection of the intrinsic properties of their main ingredients is still missing. This work focuses on the thermoelectric properties of portlandite and tobermorite, two mineral components found in Ordinary Portland Cement pastes. To this end, atomistic simulations were carried out to predict the thermoelectric properties of cement-based materials. The methodology is based on the density functional theory approach together with GW-quasiparticle and Boltzmann transport equation methods. As expected, the undoped minerals have low thermal conductivity. However, both the Seebeck coefficient and the electrical conductivity can be dramatically increased by appropriate carrier doping. In fact, an enhanced figure of merit of Z = 0.6 at 650 K and 0.79 at 600 K is observed for portlandite and tobermorite. Therefore, our results confirm that there are still much promising prospects for enhancing the characteristics of concrete materials for energy harvesting.