A gray wall with a textured appearance hangs from the load chain, it weighs almost two tons.
Every gesture counts for the companion installed at the controls of the mobile crane.
Made up of layers of raw concrete, it is one of the thirty-five walls printed in 3D concrete that gives this site its atypical character.
Five terraced houses are emerging from the ground in the heart of the Réma'Vert eco-district in Reims (Marne).
A new construction method which has received a favorable opinion from the CSTB (Scientific and Technical Center for Building).
"We are no longer in traditional construction, it is a source of pride for my team to work for such an ambitious project", underlines Sébastien Allard, site supervisor for Demathieu Bard.
A little further on, several companions are busy with the wall being assembled.
A worker generously waters his base.
“We wet it before we put the mortar.
Then, we will install the wedges and then the wall will rest and compress the mortar, ”explains Jérôme Florentin, director of project management at Plurial Novilia.
A technique that saves 50% of material
The idea of this extraordinary project is to replace the bricks or the formwork with 3D printing. A not so new idea since at the end of the 1990s, a professor at the University of Southern California had developed robotic gantries to print large concrete structures. This is the same process here. “The walls were printed by the start-up XtreeE in its workshop in Rungis (Val-de-Marne). They worked with modern concrete at the cutting edge of innovation ”. And this technique saves 50% of material because the robot calculates the exact quantities needed.
The saving in raw material is not the only advantage.
“It frees architecture,” emphasizes Jérôme Florentin.
We can imagine new forms such as curved or elliptical structures ”.
But beware, the technique remains more expensive, it takes 25% more than a classic project.
On the other hand, a real revolution is taking place on the site.
Main advantage: speed of execution.
"It will take 10 months instead of 16 months for a classic production", emphasizes Jérôme Florentin.
And on the site, there is less handling, therefore less risk of accidents.
"The site becomes an assembly place where we reduce painful tasks thanks to technology."
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And to reduce costs, 3D technology is associated with the use of prefabricated wooden modules, which will contain the technical block with kitchen, pantry, toilet and bathroom. A ViliaPrint house and its garden could thus be sold for around 200,000 euros. These accommodations ranging from T3 to T5 will be rented between 600 and 850 euros. And the rest should be written quickly. The next step will be the construction of a small collective housing in 3D printing. With the obtaining of the Atex (Technical Experimentation Assessment) issued by the Scientific and Technical Center for Building, the possibility of duplicating the technique inaugurated this month in Reims on other French sites is opening up.