Interfacial effects of thermal energy storage aggregates on the thermo-mechanical properties of cementitious composites

Interface engineering plays a pivotal role in the successful encapsulation and integration of phase change materials (PCM) into cementitious composites for building energy applications. However, the incorporation of thermal energy storage aggregates (TESA) in such composites often results in compromised mechanical properties and inefficient heat transfer due to poor interfacial compatibility between TESA and cementitious composites matrix. In this study, we presented a bottom-up encapsulation strategy combining in situ polymerization with droplet granulation to fabricate TESA using sodium sulfate decahydrate as the PCM core, achieving a high latent heat of 129.5 J/g. To overcome interface-related limitations, silicon carbide (SiC) particles were embedded within the polymer shell to form a thermally conductive and structurally reinforcing interfacial layer. Both experimental and numerical analyses demonstrated that the improved interface accelerates latent heat utilization and lowers indoor temperature peaks, thereby enhancing thermal regulation. Simultaneously, interfacial strengthening promotes better bonding between TESA and the cement matrix, mitigating strength degradation and improving durability under thermal cycling. Overall, this work revealed the pivotal role of interface design in achieving high-performance energy storage cementitious composites, offering a scalable pathway to enhance both the thermal efficiency and structural viability in sustainable building materials. • Developed a bottom-up method to fabricate salt hydrate-based thermal energy storage aggregates. • Enhanced interfacial mechanics to improve the compressive strength of TESCC by over 19%. • Optimized interfacial heat transfer to increase PCM utilization efficiency by 56%. • Revealed the interfacial mechanisms affecting the thermo-mechanical performance of TESCC.