Seebeck Effect and Mechanical Properties of Carbon Nanotube-Carbon Fiber/Cement Nanocomposites

Carbon nanotubes (CNTs) were homogeneously dispersed in a mixed solution by surface-active agents and ultrasonics, and then mixed with short carbon fibers before added into cement paste. Seebeck effect, microstructure, and mechanical properties of the fabricated composites were measured. Results show that the addition of CNTs to carbon fiber/cement composites results in improvement in the compressive and splitting tensile strengths of the composites. The addition of 0.5% by weight of cement of CNTs to carbon fiber/cement composites results in the highest increase in the compressive and splitting tensile strengths by 18.4% and 21.8%, respectively. The doping of CNTs leads to a highest increase (up to 260%) reaching 23.5 μV K−1 in the positive thermoelectric power of the carbon fiber/cement composites, when CNTs addition reaches 0.5% by weight of cement. The microscopic observation shows that CNTs act as fillers, which result in a dense microstructure of cement paste.