Effects of the addition of glass fibers, mica and vermiculite on the mechanical properties of a gypsum-based composite at room temperature and during a fire test

This work presents thermomechanical experiments whose results have led to a new formulation of composite panels for building construction. This panel has the advantage to be lightweight and 2 h firebreak. Plaster, under the β-hemihydrate form, is used as a matrix and mineral products (vermiculite, mica, glass fibers) are added as lightweight additives, mechanical reinforcement and thermal insulator. The both effects of the particles size distribution of plaster, and of the amounts of additives, on the mechanical properties are investigated at room temperature. Three approaches are proposed and compared: experimental, analytical and numerical to quantify the impact of additives on the mechanical properties. Thus, the results obtained, including porosity, density and mechanical property, permit to retain a formulation of composite. This formulation is tested under ISO 834 fire conditions to validate its use as passive protection in building construction.