In-process textile reinforcement method for 3D concrete printing and its structural performance

In-process textile reinforcement method for 3D concrete printing and its structural performance

3D concrete printing (3DCP) is an innovative technology for constructing complex freeform structures that are difficult or expensive to build using conventional construction methods. The printing of double-curved shells and aesthetically pleasing geometries for façade panels and roof elements requires a detailed investigation of the load-carrying capacity and failure mode during complex loading. Moreover, integrating reinforcement into printed elements is one of the major challenges in 3DCP for manufacturing structural components. Textile reinforcement has high formability and tensile strength and can be used as an in-process reinforcing method during printing. In this study, one layer of alkali-resistant glass textile was used to reinforce the 3D printed and mould-cast high-performance concrete curved members. The commonly used concrete printing nozzle was modified to allow ease in textile placement along the printing path. Further, the feasibility of the modified nozzle was evaluated by printing two different curved structures and was validated. In addition, two different curvatures of curved elements, with and without textile reinforcement were printed to study the effect of textile reinforcement and geometry when subjected to a point load in the middle. The deformation behaviour, crack development, and propagation were monitored using digital image correlation. It was observed that the textile reinforcement enhances the interlayer bonding leading to slower crack propagation and enhanced load-carrying capacity. An increase of about 10 % in the peak load-carrying capacity of 3D printed specimens was observed with the addition of textile reinforcement when compared to their mould-cast. Also, 3D printed specimens was observed to have larger deformation ductility compared to mould-cast specimens. Further, the textile aligns better with increasing curvature which enhances the resistance of membrane forces more uniformly resulting in a 15.5 % increase in the ultimate moment capacity. In addition, the first crack load and the ultimate load were predicted based on the arch equations and the results showed that the current method predicts the capacity with reasonable accuracy.