This work proposes a mesostructure-guided computational framework to evaluate the effective thermal conductivity (ETC) of concrete affected by aggregate and interfacial transition zone (ITZ) configurations at a mesoscopic scale. An unified aggregate shape descriptor for gravels and crushed rocks is characterized by superellipsoid covering from convexity to non-convexity, as well as random static and dynamic packings of superellipsoidal aggregates (SAs) are carried out to generate tri-phase concrete mesostructures consisting of homogeneous mortar, densely packed aggregates and their surrounding ITZs. A closed-form expression for the ITZ volume fraction is theoretically developed in the present concrete mesostructure, which is also validated using the one-point probability function simulation. Moreover, an optimized Browanian motion numerical strategy is developed to estimate the ETC of tri-phase concrete. This strategy is confirmed to be an accurate numerical technique by comparing against the Mori-Tanaka model. The present framework reveals the quantitative responses of various configurations on the ETC, which manifest rigorous “constituent-mesostructure-ETC” relations. The results are available for tailoring components to optimize ITZ structures for the improvement of thermal efficiency and durability of buildings.

中文翻译：

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混凝土的 ITZ 体积分数和导热系数：砾石和碎石的统一随机堆积模型


这项工作提出了一种细观结构引导的计算框架，用于评估细观尺度上受骨料和界面过渡区（ITZ）配置影响的混凝土的有效导热率（ETC）。砾石和碎石的统一骨料形状描述符的特点是超椭球覆盖从凸面到非凸面，并对超椭球骨料（SA）进行随机静态和动态填充，以生成由均质砂浆组成的三相混凝土细观结构、密集聚集体及其周围的ITZ。从理论上讲，在目前的混凝土细观结构中开发了 ITZ 体积分数的封闭式表达式，并使用单点概率函数模拟对其进行了验证。此外，还开发了一种优化的布劳瓦运动数值策略来估计三相混凝土的 ETC。通过与 Mori-Tanaka 模型的比较，该策略被证实是一种精确的数值技术。目前的框架揭示了ETC上各种构型的定量响应，体现了严格的“成分-介观结构-ETC”关系。结果可用于定制组件以优化 ITZ 结构，从而提高建筑物的热效率和耐用性。