Optimizing thermal energy storage in 3D printed concrete with hollow ceramsite composite phase change materials

3D printing has revolutionized construction, yet integrating phase change materials (PCMs) into 3D printed concrete (3DPC) to enhance energy efficiency remains a major challenge. This study presents a novel approach by incorporating hollow ceramsite composite phase change materials (HC-PCMs) into 3DPC, achieving an innovative balance between thermal energy storage and mechanical performance in thermal energy storage 3D printed concrete (TES-3DPC). Unlike conventional PCM-integration methods, the use of HC-PCMs overcomes leakage issues and enhances structural integrity due to their robust ceramic shell and high adsorption capacity. The impact of HC-PCMs on printing, mechanical, and thermal properties was evaluated. Results indicate that a 10 % HC-PCMs content improves fluidity, while a 30 % content increases specific heat capacity from 1.25 J/g·°C at 0 % to 1.82 J/g·°C, representing a 45.43 % increase, significantly enhancing thermal energy storage. Despite reduced extrudability due to particle interlocking, optimized extrusion speed enables successful printing. The compressive strength of the TES-3DPC with 30 % HC-PCMs remains at 48.1 MPa, and the elastic modulus is 29.4 GPa, demonstrating that HC-PCMs do not compromise mechanical integrity. Additionally, internal temperature fluctuations in 3D printed models were reduced by 6.8 °C, and the Overheating degree (OD) decreased from 3.3 °C·h to 1.12 °C·h, effectively improving thermal comfort. This study pioneers the integration of hollow ceramsite-based PCMs into 3DPC, offering a promising strategy for developing energy-efficient, thermally stable 3D printed buildings.