Making bridges circular with biomaterials

The Smart Circular Bridge project introduces a novel construction material: biobased fibres in combination with a biobased resin

When taking a stroll in the countryside of North-West Europe, it’s not unusual to be faced with violet flax fields reaching the flat horizon. This traditional crop is not only easy on the eye, it has also enabled families/farmers to make a living over generations. Thanks to the favourable climate and rich soil, flax can be seen from Caen (FR) through Belgium and all the way to Amsterdam (NL). The crop is used for traditional materials such as oil, paper, rope, linen shirts and other textiles. And since April 2022, thanks to the support of Interreg North-West Europe, a surprising new application of flax was inaugurated in Almere (NL): a brand-new pedestrian bridge!

Unlike wood and many other crops, flax is a fast-growing plant, and requires neither fertilizer nor watering to be cultivated. In times of climate change and scarce raw materials, bio-composites offer a great opportunity for the construction industry with its huge CO2 footprint and immense consumption of resources.

"The Smart Circular Bridge project introduces a novel construction material: biobased fibres in combination with a biobased resin"

Martijn Veltkamp, Design Lead at FiberCore Europe and partner in the project.

“The Smart Circular Bridge project introduces a novel construction material: biobased fibres in combination with a biobased resin. All real-life steps to come to a legally accepted bridge structure have been walked through. This pushed all partners to not just think, but also implement the innovations resulting from this project”, presented Martijn Veltkamp, Design Lead at FiberCore Europe and partner in the project.

The 15 meter-long bridge is located at the Floriade Expo site in the municipality of Almere, just outside Amsterdam. The structure is meant for bicycle and pedestrian traffic, strong enough to support 275 people. It weighs nine tonnes out of which 3.2 are made of flax. The natural fiber is combined with a bio-resin to form a light and stable material, with properties comparable to those of aluminum or light steel. The bio-resin is produced from biodiesel waste and recycled PET bottles.

“With the technical challenges now solved, the next step is to optimise the product and process, in order to make it more economically viable. A major part of this optimisation is to be derived from the long-term monitoring of the state and behaviour of the bridge”, continued Veltkamp.

A circular bridge

The construction industry needs to make a shift in material use. Reliable alternative solutions for improving material efficiency and natural resource use are lacking. In North-West Europe, a 0.5% yearly replacement of just pedestrian and cyclist bridges, equals 95.000 tonnes per year of primary raw material saved. Smart Circular Bridge promotes circular infrastructure through development and uptake of a smart circular pedestrian/cyclist bridge infrastructure system as an alternative to the traditional industry, avoiding the use of fossil raw material.

The bridge was created through the combined efforts of five universities, three municipalities and nine companies, joined by three suppliers. The partnership is now working on the development of two other bridges using the same techniques, one in Ulm (DE) and a third one in Bergen op Zoom (NL). The project has a total budget of € 6.86 M, with € 3.93 M provided by Interreg North-West Europe.

A smart bridge

As the name also says, the bridge is “smart”. Sensor technology combined with computer algorithms allow to equip structural components with sensors and follow their degradation. Material behaviour is evaluated in real time thanks to “Structural Health Monitoring”. An innovative smart sensor system evaluates input and generates warnings before critical levels of material degradation are reached. This enables real time maintenance or replacement of components. The project compensates the uncertain aspects of material-ageing with the Structural Health Monitoring system, guaranteeing the overall safety for users. This new approach has the potential to significantly boost the use of biomaterials in infrastructure.

"As Mayor of Almere, I am very proud that my city is a partner in this fantastic project and I’m very happy to see the achieved result."

Ms Ank Bijleveld-Schouten, Mayor of Almere, NL

“The bridge is meant to be recycled again! As Mayor of Almere, I am very proud that my city is a partner in this fantastic project and I’m very happy to see the achieved result. The unique bridge is made from bio-based materials and equipped with a monitoring system that helps to measure the life cycle of the bridge” said Mayor Ank Bijleveld-Schouten at the official opening of the bridge on 22 April.

EU's Bio-Economy Strategy

The EU's Bio-Economy Strategy presents the need for a shift towards biomaterials. Despite an increasing market demand, the construction industry remains cautious to implement new biomaterial applications. Due to their material properties, particularly the degradation properties, pilot initiatives such as the Smart Circular Bridge are required to demonstrate safe use and hence contribute to building industry confidence.

“We are facing a big challenge in the Netherlands. Before 2040, 85.000 bridges and viaducts have to be replaced. The construction or renovation of hundreds of thousands of bridges across Europe requires a huge amount of raw materials. As the city of Almere, we see and feel this urgency. We also want to actively contribute to national and European ambitions aiming at a climate neutral and sustainable future.”, highlighted Mayor Bijleveld-Schouten.

The 2022 Floriade Expo site opened on 14 April and will run until 9 October. Pedestrians and cyclists interested in testing the bridge are welcome daily from 10 am to 7 pm.

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