Impact of groove-and-tongue parameters on the bonding behavior between 3d-printed UHP-SHCC and cast normal concrete

The utilization of 3D-printed formworks represents a significant advancement in traditional construction practices, offering the potential to enhance structural capacity and effectively address reinforcement challenges in 3D concrete printing. Ensuring strong bonding between formwork and cast concrete is critical for structural integrity. In this study, 11 composite specimens with varying groove-and-tongue parameters including the layer number, spacing, length, and thickness of tongues undergo splitting tests. Results reveal that increasing the tongue’s layer number enhances the interfacial splitting tensile strength, whereas tongue spacing has minimal impact on interfacial strength, and a thicker tongue negatively affects the interfacial splitting tensile strength. An optimized groove-and-tongue configuration can significantly increase the interfacial splitting tensile strength from 2.10 MPa to 3.66 MPa, with a maximum increase rate of 70.4% and achieving a higher value (20.8%) than that of fully cast normal concrete. A splitting tensile strength model is proposed, with predictions aligning well with experimental results.