Thermal, mechanical, and energy-saving performance of capric acid-myristic acid/expanded perlite phase-change concrete for building envelopes

Phase-change concrete (PCC) can improve the heat-storage capacity of cement-based materials, but PCM incorporation often compromises mechanical performance. This study prepared PCC using capric acid-myristic acid (CA-MA) impregnated expanded perlite as a shape-stabilized PCM aggregate. PCM particles replaced 10%, 20%, and 30% of fine aggregate by volume, and five particle gradations were designed to examine the coupled effects of PCM content and gradation. The CA:MA mass ratio of 6:4 showed a phase-change temperature of 26 ℃ and a latent heat of 131.82 J/g. PCM incorporation increased specific heat capacity and reduced thermal conductivity, whereas excessive replacement caused evident strength loss. A 20% replacement ratio provided the best thermal-mechanical balance. Fractal analysis further indicated that PCM particle gradation affected both heat-transfer behavior and strength retention. In a DeST-h simulation for a severe-cold residential envelope in Shenyang, replacing ordinary concrete with PCC reduced annual heating and cooling loads by 1.5% and 1.6%, respectively. These results suggest that CA-MA/expanded perlite PCC is a promising thermal-storage construction material for building-envelope applications.