Construction of a social housing building using 3D concrete printing, a first in France

"It's a bit like the 3D printer that everyone can have at home, except that it's gigantic because it will encompass the entire size of the building to be constructed," Jérôme Florentin, director of project management and development at Plurial Novilia, summarized for AFP.

This subsidiary of the Action Logement group is behind this rent-controlled building project in Bezannes, a town near Reims (northeast), which has been transformed since the creation of a TGV station.

So there's a movable gantry (11 meters high, 12 meters wide) and "a print head will print all the walls," continues this manager. The walls that rise are superimposed rows of a soft, gray tab that comes out of the "printer" and then solidifies. "The ink" is "real concrete, with aggregates, pebbles that come from quarries in the region," describes the project management director.

Concrete 3D printing is nothing new in France (or anywhere else), with the technology having led to the construction of an office tower near Valenciennes (north) and houses already proposed by the same social landlord in Reims. But this time, the walls aren't delivered ready-made (as with the houses), but are being built on the site. And the ambition is quite different: a 9-meter-high building (from the ground floor to the second floor) with 2 apartments for a total of 12 m³ of living space.

Germany, Denmark, Switzerland

International cooperation proves that the final product—scheduled for the first quarter of 2026—will be explored far beyond France's borders. Alongside the French architect (Hobo Collective) and a French company (Demathieu Bard), the cast includes German technology and a Danish gantry crane (Cobod).

Wearing a yellow helmet, Chikaeze Ugwu, an applied engineer at Peri 3D Construction (a German company), is one of two German workers overseeing the gantry. Digital tablet in hand, while his compatriot Simon Wein is in front of his laptop, surrounded by the moving gantry: it's a far cry from the cliché crane-trowel-formwork. Noise pollution is minimal compared to a typical construction site.

"Here on this site we are saving 10% of materials due to the design freedom allowed by 3D with rounded shapes," when right angles reign in traditional construction, explains Hélène Lombois-Burger, director of research and development for concrete and aggregates at Holcim (Swiss group), to AFP.

The robot "can print the shape you want; in traditional construction, you're limited by the specific formwork you have to create," notes Nicolas Bouillard, deputy regional director of Demathieu Bard. This company is responsible for work that the robot can't handle (elevator shafts, staircases, floors, beams, etc.).

Reduced deadline of 3 months

"We'll save about three months on the overall lead time compared to conventional technology," says Jérôme Florentin. He doesn't shy away from the pitfall: for these prototype projects, the additional construction cost "is still around 3% compared to a traditional building." A gap that should be eliminated "in five to ten years," according to him.

The total investment is €4,5 million, including a similar, traditionally constructed building for comparison. The additional cost also comes from the concrete, which "is required to be able to withstand the loads and also be low-carbon," explains Hélène Lombois-Burger.

"But it's a building that can be delivered sooner, with rent coming in faster," adds Jérôme Florentin. This means increased productivity, with staff cut in half compared to a traditional construction site, according to him. Should we fear job losses? "The building industry is less attractive, and it's difficult to recruit," Nicolas Bouillard puts things into perspective.

"No one wants to find themselves in an environment with heavy lifting, dust, physical risks, or noise anymore," continues Hélène Lombois-Burger. She adds: "We're going to create skilled jobs, for example, in robot manufacturing or maintenance."