Effect of Form-Stable Phase Change Particle Gradation on Thermal Conductivity of Concrete

The application of phase change materials in concrete can effectively improve the thermal performance of concrete. Form-stable phase change (FSPC) particles can be used to prepare FSPC concrete to achieve this objective. However, the influence of FSPC particles on the thermal conductivity of FSPC concrete is not yet clear. In this study, the relationship between the particle gradation and thermal conductivity of FSPC concrete was analyzed based on fractal and gray correlation theory. The results show that the thermal conductivity of FSPC concrete with a fine aggregate replacement rate of 10%, 20%, and 30% was 9.16%, 13.12%, and 28.31%, respectively, lower than that of ordinary concrete. The FSPC particles have self-similarity in the fractal dimension range of 0.49–1.68. Increasing the amount of FSPC particles of 4–5, 5–6, and 8–10 mm can reduce the thermal conductivity of FSPC concrete. The use of fractal theory and gray correlation theory can effectively establish the relationship between thermal conductivity and particle size distribution of FSPC concrete.