Preparation and characterization of innovative cement mortar incorporating fatty acid/expanded graphite composite phase change material for thermal energy storage.

To explore the application of phase change energy storage materials in building energy conservation, in this study, an innovative composite thermal energy storage cement mortar (CTESCM) was developed using lauric acid-palmitic acid/expanded graphite (LA-PA/EG) as the composite phase change material (CPCM). Seven different CTESCM test blocks with different CPCM mass contents were prepared. The thermal characterization of the CTESCMs was achieved using a differential scanning calorimeter (DSC), a thermogravimetric analysis (TGA), thermal conductivity tests, and heat storage/release tests. The physical behavior was assessed using density, mechanical performance was assessed using compressive strength, and the microstructure was observed using a scanning electron microscope (SEM). The results indicate that the phase transition temperature of the CTESCMs was lower than that of the LA-PA/EG CPCM, and the latent heat consistently decreased with the decrease of the CPCM mass content. With the addition of the CPCM, which had a low-density porous structure, the thermal conductivity, density, and compressive strength of the CTESCMs decreased. CTESCM with a mass fraction of 20%C (20% cement) CPCM can be used for building energy conservation such as floor radiation heating systems.