In-Process Integration of Reinforcement for Construction Elements During Shotcrete 3D Printing

Abstract

The current state of the art for additive manufacturing often utilises horizontal layer printing approaches for a variety of materials and applications. However, it imposes restrictions on the integration of utilities, mounting fixtures, installations, and reinforcement. Particularly the integration of reinforcement into 3D concrete printing still faces many challenges. It is currently restricted by the nozzle to strand distance, the lack of bond quality, automation, and geometric limitations of the respective 3D concrete printing techniques. The following research presents a case study on additively manufactured concrete construction elements utilising the Shotcrete 3D Printing (SC3DP) technique, focusing on interlayer- and short rebar reinforcement. To demonstrate the potential benefits for an automated reinforcement integration and to uncover further challenges and research questions, a wall segment was produced using a unique combination of Interlayer Reinforcement (ILR) and Short Rebar Insertion (SRI). By incorporating these methods, it was possible to generate three-dimensional continuous reinforcement structures within the wall. The innovative approach showcased takes full advantage of the SC3DP technique, enabling the integration of reinforcement during the printing process itself, thus utilising the geometric freedom, the fast build up rate and the kinetic energy during application. This eliminates the need for premanufactured reinforcement structures, enabling a more efficient and flexible manufacturing process. Furthermore, the discussion includes the potential for surface finishing and attainment of geometrical accuracy through the direct integration of reinforcement. An outlook is given as future construction elements can be produced structurally reinforced without formwork and with a high degree of geometric freedom.