The transportation system contains a large amount of high-entropy energy, among which the pavement absorbs a large amount of solar radiation and accumulates thermal energy. Through thermoelectric conversion technology, thermal energy in the pavement can be converted into electrical energy, hence converting dissipated high-entropy energy into usable energy. Composite thermoelectric materials can be applied to pavement energy harvesting. This paper uses Bi2O3, Sb2O3, and expanded graphite as additives to prepare cement-based thermoelectric materials. The Seebeck effect and thermoelectric properties of the materials are evaluated by the thermoelectric figure of merit, ZT, and the synergistic effect to improve the thermoelectric properties between the additives is explored. The relationship between compressive strength and the proportions of the additives is analyzed and SEM on the microstructure of the specimen is conducted. A proportion of precursors with high thermoelectric performance and reasonable compressive strength is obtained, which unfolds new prospects for the application of cement-based thermoelectric materials.