Development of novel 3d thermal energy storage concrete

Abstract

Extrusion-based 3D concrete printing is presenting a prospective pathway for engineering thermally functional cementitious materials for building applications. The incorporation of microencapsulated phase change materials (mPCM) into such systems also opens a route toward emerging 4D concrete, in which printed materials exhibit temperature responsive functional behavior. A number of research teams have studied the integration of mPCM into 3D printing cementitious materials. However, a systematic multi-parameter investigation that simultaneously addresses printability, fresh-state behavior, early-age hydration, mechanical performance, physical properties, and thermal functionality across multiple mPCM dosage levels within a simplified and reproducible mix design framework is yet to be studied. This study addresses that gap by incorporating mPCM into a simplified Portland cement-based printable concrete as partial replacement of sand and comprehensively evaluating its material behavior. The system was examined by using characterization tests (SEM, XRF, FTIR, and TGA) and a broad experimental program. It includes printability, fresh state behavior, early-age hydration, mechanical performance, physical properties, drying shrinkage, mass loss and thermal response. Introduction of mPCM influenced the material response across entire characteristics examined. It affected structural build-up, hydration evolution, strength development, dimensional stability, and heat transfer behavior, while overall printability was maintained by minor adjustments in water and superplasticizer dosage. In comparison to the traditional thermal insulation materials that mainly act by resisting heat transfer, mPCM enhanced thermal performance by way of heat absorption, storage, and delayed release. It also reduced heat accumulation during early-age hardening and lowered drying shrinkage, suggesting potential benefits for crack mitigation. However, higher replacement levels associated with trade-offs in mechanical performance and early-age structural development. Overall, the results indicate that mPCM-modified 3D-printable concrete can be engineered as a thermally enhanced cementitious material with the latent heat storage capability. The research also points that simplified printable mix designs offer an effective path towards developing multifunctional cement-based materials used in additive manufacturing of energy-efficient buildings.