Experimental Study of Hardened Properties of 3D-Printed Concrete Under Compression, Tension and Shear Considering Interlayer Influence (2026-01)¶

The behavior of 3D-printed concrete (3DPC) differs significantly from conventional concrete, as 3DPC is printed in layers, leading to interface formation that impacts its hardened state mechanical strength. These interface layers are of different types according to the stacking nature, namely deposition interface (with self-weight aided cohesion due to vertical stacking of layers) and transition interface (without self-weight aided cohesion due to horizontal translation of layers). Thus, investigating the anisotropic mechanical properties of hardened 3DPC and studying the behavior of interfaces is crucial for ensuring its safe application in structural design. This research focuses on the anisotropic mechanical behavior of hardened 3DPC under compression and tension, considering directional properties owing to the interfaces. The study further investigates the shear behavior of interfaces. The study uses experimental tests such as the axial compression test for compression, split tension test for tension and couplet test for interface behavior under shear. The study compares the strength and deformation characteristics of hardened 3DPC and the bond strength between layers of different types of interfaces, through displacement-controlled monotonic static loading and quantifying the frictional properties such as cohesion and the internal angle of friction of the interfaces. The study observes a decrement of 18% for the transition interface compared to the deposition interface in terms of cohesive parameters. The study confirms that the deposition interfaces show higher resistance than transition interfaces, highlighting the latter’s weakness in achieving proper bonds between the layers and affecting the structural performance, which should be a concern for structural design.