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Phoenix represents a step forward in the realisation of circular construction with concrete. As an iteration of the Striatus bridge built in Venice, Italy, in 2021, Phoenix shows a significant advancement in the application of an unreinforced-masonry structural logic to 3D concrete printing (3DCP), mainly on circularity, environmental impact reduction, and structural robustness aspects.
Compared to Striatus, the CO2 emissions were cut by 25%, largely due to a new concrete mix developed by Holcim, which uses locally sourced and recycled materials, and the decreased reliance on single-use materials for falsework during construction. Phoenix resulted from the partial recycling of the original blocks of Striatus.
Unlike the original Striatus, Phoenix is designed as a permanent structure. Its shallower geometry eliminates the need for steps, making it more accessible and functional for pedestrian use. The bridge also features a handrail system elegantly held in place by the thrust in the balustrade arches.
To enhance assembly precision while minimising single-use falsework components, the assembly logic of Phoenix was entirely reworked. Modular falsework components were developed that integrate a minimal timber waffle structure with standard reusable, off-the-shelf steel beams to minimise the volume of single-use timber elements. Three to six 3DCP blocks were precisely assembled on each falsework module before being lifted on pre-installed scaffolding towers.
The assembly followed a predefined sequence, starting from the centre towards the supports, where a gap of a few centimetres was left from the foundations. This strategy was adopted to control the fabrication tolerances and assembly imprecisions at midspan and push them towards the last interface with the supports, where they could be compensated by filling the resulting gap with mortar before decentering.
Short credits
- ETH Zurich - Block Research Group, ETH Zurich (BRG)
- Zaha Hadid Architects - Computation and Design Group (ZHACODE)
- incremental3D (inc3D)
- Holcim
Full credits
Design
- ZHACODE: Jianfei Chu, Vishu Bhooshan, Henry David Louth, Shajay Bhooshan, Patrik Schumacher
- ETH BRG: Tom Van Mele, Alessandro Dell’Endice, Philippe Block
Structural engineering
- ETH BRG: Tom Van Mele, Alessandro Dell’Endice, Philippe Block
- Amodis: Ibrahim Alachek, Jeremy Ouedraogo, Gianluca Cardia
- Holcim : Serge Nana, Fulei Zhou
Fabrication design
- ZHACODE: Vishu Bhooshan, Heba Eiz, Taizhong Chen, Efthymia Doroudi, Shajay Bhooshan
- ETH BRG: Serban Bodea, Alessandro Dell’Endice, Vasilis Aloutsanidis, Tom Van Mele
3D concrete printing
- inc3D: Johannes Megens, Sandro Sanin, Georg Grasser, Thomas Badegruber, Nikolas Janitsch, Janos Mohacsi, Marcel Hiller, Thomas Koger
- Holcim: Christian Blachier, Mickaël Peraud, Marjorie Chantin-Coquard
Material development
- Holcim: Loïc Regnault de la Mothe, Sandrine Reboussin, Sylvain Duchand, Helene Lombois-Burger, Bilal Baz, Serge Nana
Assembly & Construction
- Bürgin Creations: Theo Bürgin, Martin Jucker, Semir Mächler
- ETH BRG: Alessandro Dell’Endice, Serban Bodea, Tom Van Mele
- Holcim: Cyril Chiale, Alain Dunand, Mickaël Peraud, Fabien Sandra, Adrien Moulin, Emmanuel Bonnet
Additional partners
- DEKRA: controls and monitoring
- Groupe NOEL: balustrade manufacturing and assembly
- Ackermann GmbH: CNC timber formwork and neoprene lasercutting
- Pletscher: tension ties
Documentation
- ETH BRG: Alessandro Dell’Endice, Serban Bodea
- incremental3D: Johannes Megens
- Holcim: Cecilia Vuillermoz
- Vincent Delesvaux
Location
Holcim Innovation Centre, Lyon, France - 45°66'23.7"N 5°09'05.32"E
