Study on the Anisotropic Mechanical and Durability Properties of 3D-Printed Recycled PVC Concrete (2026-02)¶

With the growing emphasis on sustainable construction, the integration of 3D printing technology with recycled materials has emerged as a significant research focus. This study developed 3D-printed concrete mixtures with varying contents of recycled polyvinyl chloride (PVC) by partially replacing fine aggregates, and systematically investigated their anisotropic mechanical properties and durability. Experiments included three-point bending and uniaxial compression tests along three orthogonal printing directions, as well as sulfate immersion tests coupled with SEM-based microstructural analysis to evaluate durability degradation. Results indicate that the incorporation of recycled PVC leads to a reduction in both compressive and flexural strength, with the most pronounced effect observed in the Z-direction due to weaker interlayer bonding. Interestingly, higher PVC content mitigates directional disparities, resulting in a more homogeneous compressive behavior. Durability assessments reveal that sulfate exposure accelerates property degradation, particularly in the Z-direction, and that the presence of PVC exacerbates this effect by impairing the matrix-aggregate interface. These findings provide new insight into the interplay between recycled PVC and printing-induced anisotropy. The observed homogenization of mechanical performance suggests potential for manufacturing structural components with more consistent properties, while the identified durability challenges underscore the need for strategies such as enhanced interlayer bonding and PVC surface modification. This study offers a scientific basis and practical guidance for promoting the sustainable use of recycled plastics in 3D-printed concrete.