Mechanical behaviour of geopolymers exposed to high temperatures
Résumé
The production of energy is a major topic in our industrial societies. Nuclear energy is one of the principal sources even if its use produces nuclear wastes that require management long-term. In France, the national agency for the radioactive wastes governance (ANDRA) is developing an underground storage center (CIGÉO) between the Meuse and Haute-Marne department in order to store the long term high and medium activity nuclear waste (HA and MA-VL). However, the construction of this site induces material excavation. In order to valorize these excavated materials (such as argillite), their use in construction or conditioning is studied. A way of valorization is the use of geopolymer as a fire protection. Several researches show that geopolymers have a better fire resistance than Portland cement thanks to its amorphous glass structure. However, several points are still not clear such as the impact of geopolymer formulation and testing procedures (sample size, heating rate, …). Considering this, the impact of material formulation (mineral additions in paste and aggregate percentages in mortar) on the mechanical properties exhibited before, during and after temperature rising is studied. Even if the geopolymer mechanical properties are correct after burning, it is important to test the induced strains during heating (especially with the thermal expansion coefficient (CTE) difference between geopolymer paste and aggregates), and the evolution of compressive strength and basic creep at elevated temperature.