Influence of Concrete Printing Techniques and Geometry on Shear-Compressive Capacity of Dry Concrete Joints (2026-04)¶

Additive manufacturing (AM) enables the production of complex, modular, 3D-printed concrete segments; however, achieving dimensionally controlled dry interlocking remains a significant challenge. This study systematically evaluates dry concrete joints fabricated through hybrid additive–subtractive workflows under combined shear and compression. Test blocks were produced using shotcrete, extrusion, and particle-bed AM methods, with joint interfaces formed as smooth, triangular, and sinusoidal profiles. A custom testing setup applied axial compression at three levels (up to 240 kN) and displacement-controlled shear, resulting in 87 shear–compression tests and companion material tests. The joint response was primarily influenced by interface geometry and axial precompression, with the AM route and layer orientation exerting secondary effects. Milled sinusoidal joints demonstrated the highest performance among all geometries, achieving capacities up to 90% of the monolithic reference. Within the tested set and under the present monotonic protocol, shotcrete specimens generally showed a more stable deformation response and less abrupt fragmentation than the particle-bed series. Saw-cut triangular joints provided a practical balance between capacity and fabrication efficiency. These findings indicate that interface geometry and material properties are principal factors governing shear transfer, supporting their use for modular structures, e.g., post-tensioned systems.