Production and thermo-mechanical characterization of wool-geopolymer composites

Load-bearing and thermal insulating wool waste/geopolymer composites with fire-resistant properties were produced and characterized. Two formulations, with different amounts of wool fibers, corresponding in the final composites to about 23 vol% and 31 vol%, were tested. The composites exhibited an average density of 1.0 g/cm3, with a thermal conductivity of 0.2 W/mK, and compressive and flexural strength around 9 and 5 MPa, respectively. The flexural strength and fracture behavior were improved by the presence of the fibers, which promoted the onset of a toughening mechanism in the material. Results showed that a geopolymer matrix loaded with 23 vol% of wool fibers is suitable as flame-resistant barrier, as reaction to fire is in class A2 (UNI-EN 13501-1), and as insulating structural partition in buildings because it ensures a consistent load-bearing ability coupled with thermal insulating properties, similarly to other man-made fiber products, with a considerable gain in terms of cost and environmental impact.