Fire resistance characterization of low carbon composite materials under extreme thermomechanical stresses. Application to the rehabilitation of the built heritage.

About this position

The proposed project is at the crossroads of several major issues, although of unequal scope; the development, rehabilitation and securing of underground infrastructures with a view to controlling the resources used, limiting the induced carbon footprint and reducing health and safety risks.

Urban or non-urban tunnels directly linked to the field of transport (automobile, rail, metro, etc.) or to the circulation of networks (sewers, communications) correspond to a network of existing infrastructures to be developed, maintained and rehabilitated, in particular with regard to extreme stress conditions (fires) in operating conditions. Beyond the fire risk, which is now prevalent, many typologies have been highlighted by the CETU: (disorders of the waterproofing and drainage devices; disorders of the load-bearing structure (cracking) (excessive deformations); disorders of the equipment (roadway, partition, refuge, etc.); accidental disorders (explosion). While it is undeniable that the mobilization of polymer-based composite materials (PRF: Polymer Reinforced Fabric) has made it possible to overcome certain limitations of the various implementation techniques, they are nonetheless ineffective with regard to the fire risk due to the nature of the matrix, which also has properties that are not very in line with health and safety issues.

Thus, low-carbon TRC (Textile Reinforced Concrete) composite materials (mineral matrix, geopolymer, carbon-free technical textile: plant, basalt, etc.) constitute an original and promising alternative solution.

As part of a Campus France funding program, this work will implement a new multi-scale approach with the guiding idea of studying in detail the thermo-mechanical coupling in extreme conditions after having formulated and optimized the TRC materials:

• Formulate composites (TRC) meeting the basic performance requirements for the development and rehabilitation of underground infrastructures (Materials and processes in terms of resistance, sealing for the structural work to reduce the gray energy of the structures).

• Characterization of the thermo-mechanical resistance of the selected low-carbon TRC composite material.

• Performance characterization of the system (composite/structural element). Analysis of the degradation mechanisms and kinetics of fire failure via the "hot" and residual approaches.

• Numerical modeling of the resistance of the systems (composite/structural element)