Fabrication-Aware Design Method and Experimental Assessment of a Segmented Concrete Pedestrian Bridge Using SPI Technology

This paper presents the experimental results of a 1:1 scale prototype of a segmented pedestrian bridge produced by the Additive Manufacturing (AM) technology Selective Paste Intrusion (SPI). SPI employs a technique where aggregates are selectively bound layer-by-layer in a particle bed with cement paste, enabling the 3D printing of large-scale, free-formed geometries with high shape accuracy and resolution while maintaining material properties comparable to conventionally cast unreinforced concrete. Traditional reinforced concrete structures, like bridges, often face challenges during their end-of-life phase, including limited potential for recoverability, reconstruction difficulties, or, if recycled, time-consuming material separation processes. This paper presents a novel methodology for the fabrication-aware design and additive manufacturing of a bridge structure using unreinforced concrete elements within a post-tensioned system to address these challenges. Leveraging SPI’s geometric versatility, mechanical properties, and material separability, a system of prefabricated, dry-assembled, and post-tensioned concrete elements is proposed, resulting in a bridge structure that is fully demountable, reusable, or recyclable at the end of its life cycle. While briefly outlining the fabrication-aware digital design workflow, this paper focuses on the material testing, the manufacturing process, and the experimental results of the assembly and disassembly workflow of the bridge structure. By presenting the potentials, challenges, and limitations of the proposed methods, this research aims to contribute to the understanding of SPI's applicability for automated building construction, offering insights into potential refinements and directions for future exploration.