Thermo-mechanical behaviour of hemp fibers-reinforced gypsum plasters

Due to the large latent heat related to dehydration into hemihydrate and anhydrite, gypsum is largely used to make firebreak systems. During a fire exposure, the dehydration can induce cracks inside the panels, since the loss of bound-water molecules leads to a large thermal shrinkage. In this study, hemp fibers were added into the plaster, acting as thermo-mechanical reinforcement of the gypsum panels and hindering the cracks formation. The effect of hemp fibers on the thermal behavior of gypsum panels was studied in terms of thermo-mechanical properties in isothermal conditions. Change in chemical composition and morphology of the gypsum matrix after the thermomechanical test were analysed by thermogravimetry (TGA), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Hemp fibers, even at high temperatures, preserved their “bridge action” between the fracture surfaces, increasing the tenacity of plaster and preventing its fragile collapse.