The role of microfibrillated cellulose fibres to tune the rheological behaviour of fibre-cementitious and fibre-clay mixture for 3D printing application

The use of sustainable material in the construction sector is one of the solutions to reduce its environmental impact. In parallel, this sector is facing a technical revolution with 3D printing.

The rheological behavior of cement/clay materials and its time evolution are significant in an extrusion and 3D printing process to ensure the layer-by-layer stability.

Therefore, there is an urgent need to improve the adequacy between this process and the material (cement or clay) requirements.

This proposal aims at elucidating the role of cellulose nanofiber or microfibrillated cellulose (CNF) on the complex rheological and mechanical properties of CNF-cement and CNF-clay for the further 3D printing process.

The addition of CNF will affect the fresh-state and hardened state properties (durability, mechanical strength) resulting in a change of flow behavior of the composite, which is significant to tune the 3D printing process (so-called printability index).

The processing of CNF gel can be mostly done in very low solid contents, where the high amount of water is one of the barriers to extrude the CNF gel with polymers, while the cement/clay materials are on the opposite side of the polymers extrusion process, as 25-50 wt% water is needed to prepare the slurry.

If this content is a limiting factor in the extrusion process, it could be taken as an advantage in the preparation of the slurry.

To go further, this project will explore the novel idea of UV-induced functions of CNF gel to activate the surface of the in-print layer and speeds up the hardening time due to entanglement of UV treated CNF of the mixture after having exposed by UV light.

Taking advantage of the complementary expertise of the fellow and three world-leading institutions, the proposed research aim at unleashing the potential of CNF-gel as a raw material in the construction sector.

This project will provide the candidate with a unique scientific repertoire and will be a crucial step in his future career.