Evaluating the Structural Strength of Layered Concrete Reinforced with 3D-Welded Rebar (2023-02)¶

10.1115/imece2025-166732

Allameh Seyed, Miller Roger
Contribution - Proceedings of the ASME 2025 International Mechanical Engineering Congress and Exposition

#concrete #evaluation #layer #rebar #reinforcement #strength #structure #welding

Research on 3D-welded rebar fabricated via additive welding shows tensile strengths exceeding 60 % of that of conventional steel rebar, with room to improve its mechanical properties. Similarly, concrete beams reinforced with this 3D-welded rebar made by conventional casting methods demonstrated flexural strengths around 60 % of those of counterparts reinforced with conventional rebar. However, these studies have not addressed the influence of layer-by-layer printing on mechanical behavior—an important gap.

While single-story homes constructed by 3D printing of the walls and installing prefabricated roofs demonstrate practical feasibility, multi-story and high-rise buildings cannot be made in this fashion. They require high tensile strength reinforcement to sustain wind, seismic, and thermal loads. To ensure structural safety, durability, and performance, steel rebar is the material of choice. One way to address the tensile strength requirement is to embed 3D-welded rebar during concrete printing. To achieve this, the performance of steel rebar and resulting structures should be comparable to conventional counterparts. Comprehensive evaluation of safety, reliability, and long-term behavior in reinforced printed concrete structures is essential.

This study investigates the mechanical behavior of layered concrete reinforced by 3D-printed rebar and compares the results with those of conventionally reinforced beams. To achieve this, a construction-scale 3D printer developed in the lab was equipped with a MIG-welder torch and used to fabricate a self-supporting 3D-welded rebar, later made into a reinforcement cage. Concrete beams were then made by layering concrete and embedding two cages: one made from conventional rebar and the other from 3D-welded rebar. To isolate the effect of reinforcement type, these two concrete beams-a test beam with 3D-printed rebar and a control beam with conventional rebar - were prepared under identical conditions. To determine the mechanical properties of the beams, four-point bending tests were conducted on both specimens, and load-deflection behavior was monitored. This allowed the calculation of the flexural strength of the beams. The results were compared with previous tests on cast beams containing conventional and 3D-welded rebar. The results shed light on how the layering process interacts with different reinforcement types to influence structural behavior. Results of the tests clearly indicate the effect of concrete layering and how it amplifies differences between reinforcement types. The analysis of the data shows that the test beam with 3D-welded rebar achieved flexural strength approaching that of the control sample made with conventional rebar. Layer-by-layer effects were evident in load-deflection curves, suggesting that a higher capacity for fracture energy absorption may be achievable by embedding 3D-welded rebar. Further refinement in printing strategy and the texture and geometry of embedded rebar are still needed The co-deposition of concrete and reinforcement, when optimized, offers the potential to revolutionize construction. It could enable rapid, cost-effective, and structurally sound homes and commercial buildings. To achieve parity with traditional reinforced concrete, it is necessary to carefully tune the material properties as well as the printing methods.

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@inproceedings{alla_mill.2025.EtSSoLCRw3WR,
  author            = "Seyed M. Allameh and Roger Miller",
  title             = "Evaluating the Structural Strength of Layered Concrete Reinforced with 3D-Welded Rebar",
  doi               = "10.1115/imece2025-166732",
  year              = "2025",
  booktitle         = "Proceedings of the ASME 2025 International Mechanical Engineering Congress and Exposition: Volume 9: Micro- and Nano-Systems Engineering and Packaging; Safety Engineering, Risk and Reliability Analysis; Special Symposium on Additive Manufacturing on Benchmark Test Series; Special Symposium on Power; Research Posters",
}