Quantitative evaluation of thermal conductivity of earth materials with different particle size distributions

The thermal conductivity of earth materials is closely related to density and particle size distribution. However, existing studies on the thermal conductivity of these materials have neglected the influence of particle size distribution, leading to inconsistent results and hindering the quantitative evaluation of the thermal performance of earth materials. To promote the utilization of earthen building materials in energy-efficient design, this study establishes a quantitative assessment model for the thermal conductivity of earth materials, grounded in their microscopic agglomeration morphology and pore structure properties, through experimental analyses and theoretical derivation. The average prediction error of the model is about 1.77%, which improves the precision of characterizing the thermal conductivity of earth materials. Utilizing this model, the impact of clay, sand, and gravel content on the thermal conductivity of earth materials was investigated quantitatively. The findings reveal that the thermal conductivity of earth materials attains its minimum value when the sand content is approximately 37.3%, and diminishes progressively with tthe increase of the clay content. The above findings offer a theoretical foundation for optimizing the thermal performance and fabrication process of earth materials, thereby fostering the integration and application of these materials in sustainable building systems.