Microstructural Characterization and Bonding Performance Evaluation of 3D-Printed Concrete-Mortar Composites (2026-03)¶

This study examines the microstructural and mechanical behavior of composite specimens comprising 3D-printed concrete and ordinary mortar. CT-based pore analysis was carried out for the printing, mortar, and bonding regions, and the low-order probability function was applied to quantify pore distribution and continuity. Directional tensile strength and stiffness were further evaluated using a phase-field fracture model. The printing region showed an anisotropic pore network with relatively low continuity parallel to the layer stacking, while the mortar region displayed isotropic characteristics. The bonding region exhibited an intermediate pore distribution but was notably affected by continuous pores oriented perpendicular to the stacking direction, leading to reduced interfacial bonding strength. Overall, the findings highlight how interfacial morphology governs the mechanical response of printed–mortar composite systems.