Additive Manufacturing of Reinforced Concrete—Development of a 3D Printing Technology for Cementitious Composites with Metallic Reinforcement

Abstract

Reinforced concrete (RC) is by far the most widely used composite material in the world. Despite the enormous economic importance of RC construction, there is a lack of viable concepts for its digital fabrication. While 3D printing of plain concrete has been pushed forward by a growing research community in recent years, methods for integration of steel reinforcement have only scarcely been researched and little attention has been payed to meet the practical requirements of construction sites and prefabrication plants. Therefore, full-scale implementations of current approaches are hardly available. Based on both, a sound review of R&D for digital fabrication of RC structures and an analysis of practical requirements, the present paper proposes a novel 3D printing process for RC structures, called Additive Manufacturing of Reinforced Concrete (AMoRC), viable for real-world application. In this hybrid process, consisting of an intermittent stud welding process and a continuous concrete extrusion process, segmented steel reinforcing bars are joined to form a three-dimensional reinforcement mesh and simultaneously encased with extruded concrete. The paper describes the conceptual design and development of the process and demonstrates the results of preliminary investigations on its feasibility. As AMoRC enables the operation of rebar welding and concrete extrusion process with synchronized feed rates, combination of both processes in one hybrid print head for digital fabrication of RC is a key-advantage of the proposed method.

Extrusion-based concrete 3D printing from a material perspective: A state-of-the-art review

“…Moreover, the rolling of mesh reinforcement or nailing operation should be such it does not place constraints on the motion of the 3D printer. Recently, Classen et al [156] proposed a conceptual design of a print head that also accommodates a welding unit (see Fig. 8).…”

“…Fig.8. 3D printing process with pre-placed horizontal reinforcements and robotically welding the vertical reinforcements during the printing (adapted from Ref [156]…”

Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

“…In addition, the integration of reinforcement is an important research topic. Different approaches either based on nailing layers together [ 17 ], printing the reinforcement in advance [ 2 ], or adding reinforcement simultaneously to the concrete printing [ 18 , 19 , 20 ] have already been investigated.…”

Konzeptionierung eines praxisorientierten 3D‐Druckverfahrens für den Verbundwerkstoff Stahlbeton (AMoRC)

“…Im Folgenden wird die Konzeptionierung eines neuartigen 3D‐Druckverfahrens für Stahlbeton, das sog. Additive Manufacturing of Reinforced Concrete (AMoRC) [23], vorgestellt. Das AMoRC‐Verfahren ist in Bild 2 visualisiert.…”