First-of-its-kind 3D concrete printed footbridge unveiled in Venice

The 12-by-16-metre arched footbridge is made entirely without reinforcement.
The 12-by-16-metre arched footbridge is made entirely without reinforcement.

A first-of-its-kind 3D concrete printed bridge, designed by Block Research Group and Zaha Hadid Architects, in collaboration with incremental3D and made possible by Holcim was unveiled in Venice today.

Inspired by the structural logic of the 1600s, the Striatus footbridge holds together through compression with no reinforcements, applying computational design and 3D printing, for minimal material use and maximum strength.

The 12-by-16-meter footbridge is not the longest 3D printed concrete bridge in the world. That title currently belongs to a 3.6-metre wide, 26.3 meter long concrete bridge created by a team at the Tsinghua University School of Architecture across a canal in Shanghai’s Baoshan district.

However, what makes the Striatus bridge unique, according to Philippe Block, co-director of the Block Research Group at ETH Zurich, is the bridge’s structural logic and fabrication process.

“In arched and vaulted structures, material is placed such that forces can travel to the supports in pure compression. Strength is created through geometry, using a fraction of the materials used in conventional concrete beams. This, furthermore, opens a breadth of opportunities to build with lower-strength and in a more ecologically friendly way,” he said.

What is completely new is the type of 3D-printed concrete, which the researchers developed together with the company Incremental3D. The concrete is not applied horizontally in the usual way but instead at specific angles such that they are orthogonal to the flow of compressive forces. This keeps the printed layers in the blocks nicely pressed together, without the need for reinforcement or post-tensioning. The special concrete ink for the 3D printer was developed by the company Holcim precisely for this purpose.

Because the construction does not need mortar, the blocks can be dismantled, and the bridge reassembled again at a different location. If the construction is no longer needed, the materials can simply be separated and recycled.

Using an additive process, the construction dubbed “Striatus” was built with concrete blocks that form an arch much like traditional masonry bridges.
Using an additive process, the construction dubbed “Striatus” was built with concrete blocks that form an arch much like traditional masonry bridges.

Jan Jenisch, Chief Executive Officer of Holcim said Striatus was designed by some of the best architectural and creative minds in their fields.

“It demonstrates the infinite possibilities of 3D concrete printing to enable more sustainable, faster and effective building structures, without compromise on aesthetics and functionality. Its digital and circular design uses concrete at its best, with minimal material use and blocks that can be repeatedly reassembled and infinitely recycled.”

Striatus is a complex structure made possible by a specific, custom-made ink, from Holcim’s TectorPrint range, developed by its 3D concrete printing research team. It sets a blueprint to build for the future using advanced technologies from computational design to 3D concrete printing. The next generation of inks can include Holcim’s green building solutions, from its ECOPact green concrete to its ECOPlanet green cement, including recycled construction and demolition waste.

Today, Holcim is working on a range of 3D concrete printing applications, from complex infrastructure to affordable housing. In Malawi, Holcim launched the world’s-first 3D concrete printed school, taking only 18 hours to build the walls and using 70 per cent less materials than traditional building techniques.

Holcim is also working with GE Renewable Energy and COBOD to 3D concrete print taller wind turbine towers on-site, doubling their height to harness stronger winds and capture 33 per cent more renewable electricity at lower cost.

The bridge is now open to the public in the Marinaressa Gardens during the Venice Architecture Biennale until November 2021.

Discover more about Striatus here:

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