Maxence Grangeot
Lausanne, Switzerland

Estetica del Riuso: Maxence Grangeot

Maxence Grangeot is an architect, teacher, and researcher based in Switzerland. His work explores new ways of upcycling undesirable materials into load-bearing structures. At the forefront of this emerging field, he develops tools, processes, prototypes, and tectonics that contribute to the transition towards a more circular construction industry, while actively collaborating with the sector. This interview is part of our Estetica del Riuso series and introduces our public programme, taking place in Rome on October 1 and 2 at Ex Mattatoio. Maxence Grangeot is one of four international guests featured in the lecture series “International Experiences”, dedicated to exploring different approaches to reuse. Each guest will present their work in a 20-minute public presentation. In the interview, Grangeot discusses the potential of reusing concrete rubble as a structural material, exploring how digital tools can transform demolition waste into load-bearing masonry. He also reflects on the environmental benefits of the process, which can reduce CO₂ emissions by around 80%, and on the regulatory, economic, and practical challenges of bringing these methods into wider use. More info about the public programme in Rome, HERE

 

Industry adoption

MG: There is currently strong interest from architects and engineers who see the potential for the significant environmental benefits, but perhaps more importantly, embrace it for its circular narrative and engaging aesthetics. Various projects are emerging across Europe, building on work that started during my PhD thesis: this represents quite a rapid adoption for a new fabrication process. As for clients, the enthusiasm is more nuanced. While some are sceptical, others are highly motivated, and several municipalities see great potential in making better use of concrete waste locally. For example, the city of Barcelona selected the prefabrication process for rubble reuse as a winning competition entry, with the aim of scaling it up across the city’s infrastructure. For those who aren’t convinced yet, if limits on carbon emissions and waste generation are introduced, this research will most likely become a valuable circular solution for addressing the environmental impact of the construction industry’s most problematic material.

 

Digital innovation

MG: When handling large concrete rubble from demolition, weight and irregularity are the biggest challenges to its reuse. To address these challenges, I use digitisation as a tool to facilitate tasks such as inventorying irregular shapes and virtually arranging them into high-performing masonry. In the past, this was more complicated. I iteratively refined the process to integrate the complexity of construction sites: each piece of rubble is scanned using a single photograph taken with a phone; everything is planned in 2D and assembled manually  using a small crane. Today, beyond converting the process into a user-friendly app, the challenge lies in enabling masons to adopt the process without the need for experts.

 

Impact & implementation 

MG: An 80% reduction in CO₂ emissions! This is because the volume of newly needed concrete compared to a standard wall is reduced by around 80%, and because there is much less steel reinforcement. Depending on parameters such as transport distances, the availability of electric machinery and the binder used for the infill concrete —all of which vary by region— this reduction may vary slightly, but the order of magnitude remains the same. Regulatory frameworks vary significantly from one country to another, easing or slowing adoption; for example, it’s easier in Switzerland than in France. Still, existing standards for irregular stone masonry and concrete can be leveraged to design and dimension load-bearing structures. These are the standards we used across all demonstrators and projects. We also conducted some load tests, including at full scale, which gave us more confidence. Ideally, broader structural testing campaigns would supplement these findings and inform tailored regulation. Even without this additional testing and regulation, the process is already good enough to be used in practice and adopted by the market. However, it requires a significant amount of additional labour compared to regular concrete casting, which impacts costs, and there are still a few details that could be improved. The exciting part of embracing this construction system now is to be part of its development and refinement!

 

Skills & training

MG: The goal of this new fabrication process is to rely on existing tools, expertise, and supply chains. I see this as a silent innovation with enormous potential: anyone willing to adopt it locally can! Masons have the skills to assemble rubble pieces and cast the voids; structural engineers have the skills to dimension single-leaf masonry walls. Recycling centres and demolition sites already have an abundant supply of concrete rubble available locally and all year round. Every precast facility has an overhead crane and a concrete drill. 

Today, there is still a need to guide people through the process the first time they do it, as this is not yet tacit knowledge. After that, it should snowball, and this assistance won’t have to come from me. That’s the beauty of open-source technology: prioritising the environment over proprietary technology and profits. We urgently need scalable and free solutions!

 

Barriers & costs

MG: Costs are mainly driven by labour, material and tools. These vary significantly by region. Evidently, this reuse method is more easily adopted in regions where labour is abundant and new materials are expensive. Where labour is expensive, I’ve refined the fabrication method over the years to minimise it, in particular through horizontal prefabrication. This requires more powerful lifting machinery than simply stacking rubble pieces in layers of mortar, but those regions are adequately equipped. 

As previously mentioned, it is also a matter of time before concrete casting and waste become more expensive due to environmental taxes.

 

20260914Lecture Maxence Grangeot2 ➡️ Pile of rubble.20260914Lecture Maxence Grangeot3 ➡️ Handling irregular concrete rubble with available tools.20260914Lecture Maxence Grangeot4 ➡️ Scanning rubble pieces in 2d using a phone picture.20260914Lecture Maxence Grangeot6 ➡️ Assembling rubble pieces into single-leaf masonry walls.20260914Lecture Maxence Grangeot6 ➡️ Masonry walls from large concrete rubble.20260914Lecture Maxence Grangeot7 ➡️ Prefabricated structural walls from large rubble.20260914Lecture Maxence Grangeot8 ➡️ Public pavilion made of reclaimed concrete.

All Ph. Maxence Grangeot. SXL & CRCL EPFL

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