Technological Aspects of Fabricating a Reinforced Concrete Shell Using 3D Concrete Printing (2025-11)¶

The article focuses on the technological aspects of fabricating a reinforced concrete shell using concrete 3D printing combined with polystyrene formwork. A comprehensive literature review was conducted to analyze recent advancements in additive manufacturing methods for shell structures, with a particular emphasis on the development and application of flexible and stay-in-place formwork systems. A step-by-step manufacturing procedure for the test shell element was implemented, including the generation of a digital parametric model, followed by the fabrication of a custom polystyrene mold. The mold was assembled using layered foam sheets, which were cut according to pre-defined templates, bonded using adhesives, and manually refined to ensure geometric accuracy. The digital model was processed in CAD software and converted into a format suitable for slicing. The slicing operation was performed to define the layer height, printing path, and tool trajectories. Based on the generated G-code, a robotic concrete printer (console-type, “UTU 3D”) was employed to execute the additive layering process. The concrete was deposited layer-by-layer on the pre-installed polystyrene form, beginning from the bottom ring, which was reinforced with embedded steel bars to accommodate lifting hooks. Thixotropic concrete mix was used to maintain the stability of each deposited layer and to prevent slippage on the curved surface of the mold. Short pauses between layers were introduced to manage curing and maintain interlayer bonding. The finished shell was allowed to cure under ambient conditions until the desired structural strength was achieved. The study confirmed the feasibility and efficiency of combining foam-based formwork and 3D printing for creating thin-walled curved concrete structures, offering significant potential for use in both experimental and industrial-scale applications in the construction industry. Further research is aimed at conducting full-scale tests of the shell under the action of quasi-uniform static loading in order to determine the bearing capacity and deformability of the structure.