Tailoring the thermal conductivity of functional cementitious composites with micro core-shell particles: A multiscale homogenization study

Abstract

Micro core-shell particles have been highlighted in developing energy-efficient functional cementitious composites (FCCs). In this paper, a multiscale model is established to predict the thermal property of cementitious matrices containing micro core-shell particles. Based on the composite material theory, the interfacial thermal conductance and inclusion size distribution are introduced to the Mori-Tanaka homogenization scheme. Following the scale division of FCCs, the effective thermal conductivity is homogenized step by step from the cement paste level to micro-encapsulated cementitious composites level. In what follows, the coupling effects of composition, microstructural and physical aspects are quantified through the model parametrization. As validated by experimental results, accurate numerical predictions can be obtained with the variations of w/c ratio, hydration degree, and mix proportion. Numerical parameter analysis further reveals that the thermal conductivity and volume fractions of composition phases dominate the maximum thermal design range of FCCs, while the size-dependent interfacial thermal conductance matters more when the thermal conductivity of shell material is lower than that of the core material. The findings provide a theoretical basis for the thermal design of multi-phase composites, and contribute to the rational utilization of micro particles to achieve desirable thermal properties of FCCs.