Study on thermal conductivity of 0D/1D/2D carbon filler reinforced cement composites with phonon physical model

Thermal conductivity of cement composites is crucial for developing various sustainable engineering structures, creating an urgent need to elucidate the influencing factors and their associated mechanisms. Introducing various 0-, 1- and 2-dimensional carbon fillers into traditional cement composites with tailored thermal conductivity demonstrates great potential for practical engineering applications. However, limited studies have been done on the thermal conductivity of cement composites involving temperature- and pore size-dependent mechanisms. This work firstly attempts to develop a comprehensive micromechanical framework combining phonon thermal transport in carbon fillers and phonon boundary scattering in pores. The overall thermal conductivity of 0D-carbon black (CB), 1D-carbon nanotube (CNT) and 2D-graphene nanoplatelet (GNP) reinforced saturated/dry porous cement composites subject to temperature is predicted. The effects of porosity, saturation and the attributes of pores and the carbon fillers are considered. It is found that the order of the contribution of the carbon fillers to the improvement of the thermal conductivity is 2D-GNP>1D-CNT>0D-CB. The effective thermal conductivity of the porous cement composites tends to decrease as the temperature rises. Furthermore, as the aspect ratio of the carbon fillers increases, the thermal conductivity of the composites with 1D-CNTs and 2D-GNPs increases and decreases, respectively. The effective thermal conductivity of the cement composites with random distribution of pore size is significantly higher than that with uniform distribution. The effective thermal conductivity of the saturated porous cement composites is less sensitive to the aspect ratio of the pores compared to their dry counterparts. This work provides guidelines for optimizing the thermal conductivity of porous cement composites for various potential engineering applications.