Wool-geopolymer composite boards with insulating and fireproof properties

Thanks to its specific properties, sheep wool is particularly suitable for the design of insulating systems, especially if coupled with other materials that may impart additional mechanical properties. In this regard, if considered as potential replacement of other synthetic fibrous materials, sheep wool has the additional benefit of being completely hazard-free for human health and has lower costs. In this study thermal insulating boards were designed and produced by embedding different amount of wool wastes in a geopolymer matrix. In addition to showing insulating properties, the boards are non-flammable, thanks to the geopolymer binder that prevents the fibers to ignite and, consequently, the composite to degrade in case of fire. In addition, the ceramic nature of the matrix allow the composite to be used also as self-bearing elements, thanks to enhanced mechanical properties. Thermal and fireproof properties of the boards were evaluated by thermogravimetric analysis, thermal conductivity and cone-calorimetry tests, while mechanical properties were determined by 3-points bending tests and compressive strength tests. Obtained results showed that a geopolymer matrix loaded with 10%wt of wool fibers can ensure thermal insulating and fireproof properties (class A2 according to UNI-EN 13501-1) similarly to other synthetic products but with a considerable gain in terms of environmental impact.