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.

中文翻译：

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基于声子物理模型的 0D/1D/2D 碳填料增强水泥复合材料的热导率研究


水泥复合材料的导热性对于开发各种可持续工程结构至关重要，因此迫切需要阐明影响因素及其相关机制。将各种 0 维、1 维和 2 维碳填料引入具有定制导热性的传统水泥复合材料中，显示出实际工程应用的巨大潜力。然而，关于水泥复合材料的热导率的研究有限，涉及温度和孔径依赖性机制。这项工作首先尝试开发一个综合的微力学框架，将碳填充物中的声子热传输和孔隙中的声子边界散射相结合。预测了 0D-炭黑 （CB）、1D-碳纳米管 （CNT） 和 2D-石墨烯纳米片 （GNP） 增强饱和/干多孔水泥复合材料在温度下的整体热导率。考虑了孔隙率、饱和度以及孔隙和碳填料属性的影响。研究发现，碳填料对提高热导率的贡献顺序为 2D-GNP>1D-CNT>0D-CB。多孔水泥复合材料的有效导热系数随着温度的升高而趋于降低。此外，随着碳填料长径比的增加，具有 1D-CNT 和 2D-GNPs 的复合材料的热导率分别增加和降低。孔径随机分布的水泥复合材料的有效导热系数显著高于均匀分布的水泥复合材料。与干法水泥复合材料相比，饱和多孔水泥复合材料的有效导热系数对孔隙的纵横比不太敏感。 这项工作为优化多孔水泥复合材料的热导率提供了指导，以用于各种潜在的工程应用。