This thesis aims to develop new finishing materials based on cellulose and raw earth for the building and architecture sector. The main objective is to produce fine, resistant materials that can serve as an alternative to conventional finishing materials.
To design these materials, fine-granulometry raw earth from aggregate quarry waste was combined with cellulose in various forms: virgin or recycled fibres, micro-fibrillated cellulose (MFC) and cellulose derivatives. The work first explored the production of MFC with low environmental impact, with a view to using this resource as reinforcement in earth-fibre composites. The core of the project then focused on the manufacture of fine earth-fibre materials using innovative processes: twin-screw extrusion, foaming and 3D printing. The twin-screw extrusion process, which has been patented, has made it possible to produce fine materials with a high fibre content (≥ 30%) and good mechanical properties. These performances are due to the alignment of the fibres and the addition of a cellulose derivative that facilitates extrusion while acting as a binder, thus offering a promising alternative to plasterboard.
Foam materials have also been developed to produce lightweight, fire-resistant and compression-resistant products, offering a potential alternative to false ceiling tiles.
Finally, a formulation based on raw earth and MFC has made it possible to produce complex structural elements using 3D printing.
A collaboration with design students has resulted in the design of over 200 prototypes of earth-fibre materials for various applications: space separators, solar filters, acoustic dampers, etc. All of this work demonstrates that it is possible to develop different types of bio- and geo-sourced materials from the same raw materials by adapting the manufacturing processes, thus paving the way for various applications in the field of finishing materials for buildings.
