Novel Interlocking Nozzle Geometry for Enhanced Interlayer Strengthening in 3D Concrete Printing (2025-08)¶

3D Concrete Printing (3DCP) represents a pioneering advancement in the construction industry, leveraging additive manufacturing techniques to fabricate complex concrete structures with precision and efficiency. However, the mechanical integrity of 3D-printed concrete is often compromised at the interfacial regions between layers, which exhibit weaker mechanical properties than traditionally cast materials. This inherent weakness at the interface leads to a significant reduction in overall structural performance. This study investigates the enhancement of interlayer bonding strength through the development of a novel interlocking nozzle geometry in the 3D concrete printing process. The proposed nozzle design aims to create mechanical interlocks at the interface of successive vertical and horizontal layers, thereby increasing the contact surface area and enhancing shear resistance. By optimizing the shape of the nozzle, the printed layers exhibit a unique interlocking pattern that counteracts delamination and improves load transfer across layers. Experimental trials were conducted using a custom-designed nozzle, tailored to produce the interlocking geometry. Concrete specimens were printed and subjected to interlayer shear strength, flexural performance, and compressive strength assessments. The mechanical properties of these interlocked samples were compared against control samples printed using conventional flat nozzles. The results demonstrated a marked improvement in interlayer shear strength, with the interlocking geometry providing enhanced cohesion between layers.