Thermoelectric properties of metashale geopolymer mortar doped with graphite powder

Abstract Building materials with favorable thermoelectric properties can become a supplementary source of clean energy due to their ability to convert waste heat into electric energy. Depending on the thermoelectric conversion effectivity defined by the Seebeck coefficient, constructions made of these materials can serve as civil engineering energy harvesters. Since the conversion effectivity of common calcium(alumino)silicates (cementitious materials, geopolymers) is low, doping with electrically conductive admixtures is a crucial step to handle the issue. The paper is focused on the design of metashale mortar doped with graphite powder (3 wt.%), determination of its common material properties, as well as experimental determination of thermoelectric properties. The maximum thermoelectric voltage (161.65 mV, ΔT = 130 °C), Seebeck coefficient (538 μV K -1 ), and figure of merit (∼ 10 -9 ) revealed significantly better thermoelectric performance than cement pastes or alkali-activated slags doped with multi-walled carbon nanotubes and if of promising thermoelectric conversion potential.