Robotic knitcrete: Computational design and fabrication of a pedestrian bridge using robotic shotcrete on a 3D-Knitted formwork

Philipp Rennen*, Stefan Gantner, Gido Dielemans, Lazlo Bleker, N. Christidi, Robin Dörrie, Majid Hojjat, Inka Mai, Mariana Popescu, More Authors

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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The research project presented here aims to develop a design-informed manufacturing process for complex concrete shell structures in additive manufacturing and thus overcome limitations of traditional construction methods such as formwork- and labor intensity. To achieve this, an effort was made to merge the two technologies of CNC knitted stay-in-place formwork, known as KnitCrete, and robotically applied shotcrete, known as Shotcrete 3D Printing (SC3DP), and thereby reduce their respective limitations. The proposed workflow unites both digital fabrication methods into a seamless process that additionally integrates computational form finding, robotically applied fiber reinforcement, CNC post processing and geometric quality verification to ensure precision and efficiency. As part of a cross-university, research-based teaching format, this concept was implemented in the construction of a full-scale pedestrian bridge, which served as a demonstrator to evaluate the capabilities and limitations of the process. While overcoming some challenges during the process, the successful prove of concept shows a significant leap in digital fabrication of complex concrete geometry, reducing reliance on labor-intensive methods. The results shown in this paper make this fabrication approach a promising starting point for further developments in additive manufacturing in the construction sector.

Original languageEnglish
Article number1269000
JournalFrontiers in Built Environment
Publication statusPublished - 2023


Funding Information:
The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The Authors gratefully acknowledge the German Research Foundation (DFG), for funding the collaborative research center TRR 277—Additive Manufacturing in Construction (Subprojects A04, A05, B05, C02 and C06) and the DFG Large Research Equipment, Digital Building Fabrication Laboratory (project numbers 416601133 and 414265976). We acknowledge support by the Open Access Publication Funds of Technische Universität Braunschweig. PR gratefully acknowledges Holcim Innovation Center for funding his research work.


  • additive manufacturing in construction
  • digital fabrication
  • flexible formwork
  • green-state post-processing
  • knitcrete
  • robotic fiber winding
  • shotcrete 3D printing
  • stay-in-place formwork


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