Compatibility between gypsum and polyamide powder waste to produce lightweight plaster with enhanced thermal properties

► This paper presents an experimental study on the use of polyamide powder waste. ► Mixtures are prepared with different volumes of polyamide waste. ► Plasters do not show any deleterious effect by the incorporation of this polymer. ► We find new composites materials potentially useful for thermal insulation purposes. This paper presents the results of an experimental study on the use of polyamide powder waste to produce a new lightweight plaster material with improved thermal properties. Plaster blends were prepared using different volumetric proportions of polyamide. The characteristics of the tests specimens were defined and tested by fixing the consistency at a good workability and then determining the mechanical properties, Shore C hardness and the water vapour permeability that correlates with the pore structure obtained with Mercury Intrusion Porosimetry (MIP). The compatibility of the interface zone of materials was analysed using Fast Scanning Electron Microscopy (FSEM), in order to define the effect of the polyamide on the microstructure of the lightweight plaster. Moreover, its thermal behaviour was examined by thermogravimetry and thermal conductivity analysis. Our results show that an increase in the amount of polyamide affects the properties of the plaster, decreasing its density and mechanical properties, as well as increasing its permeability and its thermal resistance. These results confirm that plasters produced with recycled polyamide are comparable to lightweight plasters made with traditional materials.