In the same way as for the walls of the castle overlooking the nursery, lime is used in the stability of the walls as a binder for the local aggregates. Without reinforcement, human hands compacted successive layers, reinforcing the horizontality of the structure. A laminated timber roof rests and covers the jewel case. A star-shaped framework organizes and sets the rhythm of the interior spaces through the four living units, open to protected courtyards. The spaces are simple, clear, and bright. The many interior visual connections and the two central patios encourage cross views and transparency.
This apparent simplicity enhances each material, each detail. The precise implementation, using the right material in the right place, creates a perfect balance between structure and space. Local craftsmanship and the arrangement of manufactured elements highlight the hand of each artisan. The pronounced mineral quality of the nursery, combined with the protective wooden framework, aims to reinvent architecture, respectfully and sustainably integrating into the site. To anchor the building to its territory, structural and chromatic research on the concrete was carried out during the construction phase between the architects, the company, and the engineering office.
Two tests were performed with aggregate residues from a nearby quarry: one using a cement binder, the other using lime. They revealed the impact of lime on color. It enhances the beige hue of the limestone while respecting structural constraints. The site-compacted concrete has no reinforcement or lintel. It is associated with a simple construction system: continuous concrete footing, pre-slab, and prefabricated wooden framework. This project was a real experimental site, involving both local officials and the workers.
They aimed to develop new skills and techniques. Due to its uniqueness, material, and color, this concrete invites every visitor to question and embrace it. The concrete used is called “dry” site concrete. It was produced from a mixture of 0/20 gravel, NHL-5 lime from Saint-Astier, and water. Prepared on-site, the concrete was placed in a dry consistency into a formwork in successive horizontal layers of 12 cm, then compacted to 10 cm using a pneumatic tamper. This step needed to be carefully done to achieve a minimum dry density of 2,150 kg/m3 to ensure stability.
To improve work pace and reduce misalignments in the walls, which can lead to defects, the company studied the implementation of a sliding formwork. The final appearance is that of a rammed-earth wall, light in color, tending toward a natural beige. The site concrete is treated on the surface with a mineralizing agent. It is protected at the base by a concrete foundation and at the top by an aluminum coping with a significant overhang