Preparation and Properties of Expanded Perlite-Based Paraffin Phase Change Reinforced Concrete

Phase change materials (PCMs) exhibit high thermal energy storage capacity but typically suffer from degraded mechanical properties. Research on phase change concrete (PCC) incorporating silica fume (SF) and fly ash (FA) has been conducted to compensate for this mechanical deterioration, thereby achieving an improved balance between thermal and mechanical performance. The compressive strength variation in concrete with varying PCM dosages was investigated. Results show that reinforced PCC exhibits significantly enhanced compressive strength compared to conventional PCC, particularly at higher PCM contents, where the reinforcing effect is most pronounced. When the PCM content was 40%, the compressive strength of the reinforced group was 33.61 Mpa, which was 25.71% lower than that of the reinforced group with 10% PCM content; in contrast, the compressive strength of the conventional group dropped to 26.25 Mpa, with a reduction in as much as 40.32%.Scanning electron microscopy (SEM) analysis demonstrates that thorough mixing enables effective paraffin (PA) encapsulation within expanded perlite. The incorporation of SF and FA significantly reduces the porosity, thereby forming a more compact microstructure under high PCM dosage conditions and promoting a more thorough hydration reaction, which in turn significantly enhances the mechanical properties of PCC.