Construction detailing in 3D concrete printing from real-world building projects

3D concrete printing (3DCP) is increasingly recognized as a promising technology for enhancing productivity, reducing material consumption, and advancing the digitalization of construction processes. While existing research has predominantly focused on material development, printing technologies, and laboratory-based performance testing, empirical evidence from real-world construction projects remains limited—particularly regarding the implementation of construction detailing. This study presents a comparative field study of extrusion-based 3D concrete printing projects in Germany using a single printer platform (COBOD BOD2) and a hybrid wall construction approach. The investigated system combines printed mortar-based stay-in-place formwork with conventionally reinforced concrete cores for load-bearing walls, while non-load-bearing exterior walls consist of printed mortar shells with insulation infill. The research combines field studies, project documentation, and semi-structured expert interviews with key stakeholders, including architects, printer manufacturers, and material suppliers. The analysis focuses on the execution of critical construction details, such as plinth connections, wall openings, and lintels, which represent key interfaces between additive manufacturing and conventional construction processes. The results show that, despite the potential of 3DCP to enable efficient fabrication of monolithic wall structures without conventional formwork, the realization of construction details still requires hybrid construction approaches that integrate automated printing with conventional techniques and manual interventions. Recurring challenges include dimensional tolerances, material flow behavior, and structural constraints, which necessitate temporary supports, post-processing, and adaptive design strategies during construction. By comparatively analyzing two realized construction projects and contextual observations from additional planning-stage projects, this study provides practice-oriented insights into current detailing approaches in 3D concrete printing and identifies recurring implementation challenges and hybrid solution strategies. The findings contribute to a better understanding of the integration of additive manufacturing into construction workflows and highlight key areas for future research, particularly in the standardization and automation of detailing processes.