A 7m pedestrian bridge in the Netherlands has been unveiled as the world's first structure of its kind using a concrete mix that the developers say is carbon‑neutral.

The structure, built by by construction firm Heijmans and materials company Paebbl, uses a combination of Paebbl’s carbon‑storing material, biochar and recycled aggregates. The project partners said the mix contains 75% circular raw materials and contains no primary sand or gravel.

According to the consortium behind the project, 30% of the cement in the concrete was replaced with Paebbl’s material, and the resulting deck permanently sequesters about 66kg of CO₂. They report an embodied‑carbon reduction of nearly 30% compared with a low‑carbon reference concrete.

Cement production is a major source of industrial greenhouse gases; industry studies put it at around 8% of global CO₂ emissions. The companies say Paebbl’s product both stores captured CO₂ in a stable mineral form and can replace part of conventional cement, offering a route to lower‑carbon construction materials.

Paebbl’s process is said to accelerate natural mineralisation reactions that lock CO₂ into minerals by a factor of a million. The firm claims its materials can sequester up to 300kg of CO₂ per 1,000kg produced, while also cutting embodied carbon in concrete by as much as 30%.

The bridge project was constructed as a collaborative effort where Heijmans led and built the structure, HCM Cement supplied an optimised cement formulation, Van der Kamp B.V. produced the concrete, CarStorCon® Technologies provided biochar integration and Urban Mine supplied recycled aggregates.

Engineers involved report that the CO₂‑neutral mix met standard strength requirements for the pedestrian bridge, indicating that a high proportion of circular inputs need not degrade structural performance. The partners present the project as a demonstration that conventional concrete construction can move towards circularity and reduced emissions.

Heijmans innovation manager Nick Vervoort said: “At Heijmans, we believe that innovation in construction must address the climate crisis head-on.

“This bridge proves that carbon-neutral structural concrete is not a future aspiration, it’s achievable today.

“For the first time, CO₂-neutral concrete has been poured using an innovative mix of materials: Paebbl, biochar and recycled concrete.

“This demonstrates what collaboration and ambition can achieve. We’re very proud that the concrete mix used in this bridge is fully CO₂-neutral and contains 75% circular raw materials.”

Paebbl vice president of products Ana Luisa Vaz adds: “A 30% cement replacement rate in structural concrete is our highest to date.

“This demonstration pedestrian bridge demonstrates that carbon-storing materials aren’t just viable for decorative or non-structural uses, they’re ready for real infrastructure.”

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