Cycle-Terre: Soil as raw material for circular construction

Soil excavated for building and infrastructure projects is considered waste and is often used to fill quarries, or simply dumped somewhere. But for Cycle Terre, soil is raw material. The French project uses it to create value in the circular economy. With European funding, a factory was built just outside Paris to produce unfired bricks. Project leader Silvia Devescovi: “It is new territory on the one hand, but strangely enough it is also an old, forgotten construction technique that we have had to learn anew”.

The idea for Cycle Terre originated at the Terres de Paris conference (2016), which showed that it is possible to make building materials from raw earth from locally mined land. A call for projects of the Urban Innovative Actions, an initiative of the European Commission, brought the parties together for the preparation of pilot project. The Parisian suburb of Sevran, once an industrial stronghold but which has lagged behind since the 1980s and 1990s, was keen to take part. A lot of digging has already been done within the municipal boundaries, because in 2024 (if everything goes according to plan) the city will get two new metro stations, extensions of the network around the French capital, which will host the Olympic Games that year.

Circular urban renewal

Sevran, which lies some 13 kilometres north-east of the périphérique and has a population of over 51,000, is a poor city that is eager to try new things, says the urban renewal project manager. There is a need for new impetus after the departure of industry at the end of the last century opened the door to unemployment and crime. Devescovi: “Cycle Terre is still a small-scale project, but it is visible. And even though we do not yet employ many people, they are very proud to work there.”

Cycle Terre’s innovative production process has to be done precisely so that the sturdiness of the building materials can be guaranteed. Besides the ‘raw’ bricks, Cycle Terre also manufactures cement and wall coating from excavated soil, and hopefully soon also building panels. Devescovi: “There is a lot of demand for that, even though it is very innovative and not very well known yet. We are still looking for new funding for it.”

Collaboration with Reeleaf

The opening of the factory recently completed the implementation phase of the project. Reeleaf has been on board from the moment the European funding was granted for the financial management and to ensure that all European legislation is complied with. Devescovi: “The entire subsidy goes to the city of Sevran, which in turn has to distribute the money among all the partners, which is a great responsibility. It is very nice to work with Reeleaf, because they know the system well and give very good guidance. They can tell you exactly what is possible and what is not, and under what conditions. They work very meticulously and systematically, but at the same time are flexible and intelligent in finding solutions.”

Pioneering with raw earth

Was all the knowledge available at the start of the project for the implementation? Certainly not, says Devescovi. Cycle Terre has thirteen implementation partners and even for the experts in earth construction that are included, there was and is still a lot to discover. Parts of the project therefore had to be changed during the course of the project. “Few decisions had been made at the start. It was still uncertain what our product would be, we did not yet have a site for the building, we did not yet know where we would have to get the excavated soil. In fact, everything had to be researched from the start.”

Project surrounded by uncertainty

For Devescovi, it was initially quite disconcerting that the project was surrounded by so much uncertainty right from the start. New insights constantly led to changes in the plans. “It is a miracle that it all worked out,” she says now. “We were able to stay true to the original idea and did not have to jettison the values we had fought for. But as project manager, I had to accept the uncertainty of not knowing whether the project would ever be delivered. We just did our best and tried not to think too much about the end goal.”

Regulations get in the way

Although production is not yet 100% functional, the factory and machines are now in place and dozens of people come every week to see how the materials work, says Devescovi. “Everyone is very enthusiastic. At the same time, we are still looking for good solutions for certain parts of the process. The biggest challenge now is how to get the excavated soil. Our project is relatively small-scale and the quantities are too small for transporters to be profitable. There are also regulations that stand in our way, because you can’t just do whatever you want with waste. You have to know exactly where it comes from and where it is going. Although we have a solution now, it relies heavily on the goodwill of stakeholders. Ideally, we don’t depend on that, and we have a solution that everyone is happy with.”

Hope for the future

“Most of us are still like: did it all really work out? We’re not quite there yet, but there is confidence. All stakeholders believe that this project will succeed. Sevran is a poor city with a lot of crime, but now we really have something we can be proud of. It has already done a lot for the image of the city. My hope for the future is limitless.”