Study on electrical characteristics and properties of cementitious composites with functional fillers

Abstract Cement-based thermoelectric materials offer the capability to convert usable environmental heat absorbed by building surfaces during summer into electrical energy, holding significant engineering potential for green, low-carbon initiatives and energy recovery. Two types of functional fillers, namely graphene (Gr) and carbon black (CB), were incorporated at three different volume fractions—0.2%, 0.4%, and 0.6%—into the cement composites. The compressive strength was measured, and resistivity was evaluated using a two-electrode method to investigate temperature dependence and the Seebeck effect. Furthermore, the microstructure of the composites was examined via scanning electron microscopy (SEM). The experimental results indicated that the highest percentage increase in compressive strength was achieved at a functional filler content of 0.4 vol%. Electrical resistivity exhibited a negative correlation with temperature, and higher filler content facilitated the formation of conductive networks, leading to reduced resistivity. The lowest resistivity value at 100 °C was observed in samples with 0.6 vol% graphene (Gr). Furthermore, at the 0.6 vol% functional filler content, Gr demonstrated comparatively enhanced thermoelectric performance. SEM observations revealed that the mechanical, temperature-sensitive, and thermoelectric properties were strongly influenced by the distribution and interconnection of the functional fillers within the cement matrix.