
The Phoenix bridge, a successor to the first-of-its-kind Striatus presented at the 2021 Venice Architecture Biennale, is a remarkable evolution in 3D-printed concrete construction.
Developed by Holcim, in collaboration with Block Research Group at ETH Zurich; Zaha Hadid Architects Computation and Design Group (ZHA CODE); and incremental3D; Phoenix is constructed from 10 tons (10.16 tonnes) of recycled materials, including aggregates from the original Striatus blocks.
Using Holcim’s proprietary technology, the concrete ink for Phoenix incorporates an optimized low-carbon formulation, resulting in a 40 per cent lower CO2 footprint compared to the 2021 Striatus bridge and an overall carbon footprint 25 per cent lower than the original structure. The circular construction, powered by computational design and 3D printing, enables a material reduction of up to 50 per cent without compromising performance.
Built solely through compression without reinforcement, Phoenix’s blocks are designed for easy disassembly and recycling, adhering to circular principles. Located at Holcim’s Innovation Hub in Lyon, France, the project demonstrates the successful integration of circular construction and 3D concrete printing, achieving significant carbon reductions.

Edelio Bermejo, head of global research and development (R&D) at Holcim, expresses excitement about Phoenix, highlighting the collective goal of demonstrating circular and low-carbon infrastructure. Philippe Block, co-director of Block Research Group at ETH Zurich, emphasizes the sustainable and circular approach, aligning with historical principles of masonry arches. Shajay Bhooshan, head of ZHA CODE, views Phoenix as a significant milestone in technology readiness, showcasing advancements in digital design tools and tight integration with robotic concrete printing parameters.
“Thanks to its design principles, Striatus already represented 3D concrete printing in its purest possible form. Now, after two years and in its second iteration, Phoenix adds a largely reduced carbon footprint and permanence according to building codes along with many other further improvements. Consequently we, the incremental3d team, are very excited about Phoenix and we are looking forward to many other projects that will evolve in similar spirit,” says Johannes Megens, co-founder of incremental3D.