Optimization of Alkali-Activated Mineral Wool Mixture for Panel Production

A significant amount of mineral wool waste is generated during the construction and demolition of buildings. At the moment, most of this material ends up in a landfill without further utilization. Alkali activation is one technology already recognized to produce low carbon dioxide binders and other products/materials from several industrial by-products, and could also be employed to recycle mineral wool waste. This study shows the result of milling and homogenization of different types of wool waste and their subsequent use as precursors in the alkali-activation process. Two different types of mineral wool waste were taken from the mining company Termit (Slovenia). Stone and glass wool were milled, pulverized and sieved below 63 μm. After homogenization, different alkali-activated pastes were prepared using two different alkali activators (NaOH and/or Na–water glass). The compressive and flexural strength of each alkali-activated material was measured, showing higher values for glass wool in comparison to stone wool. In addition, different curing temperatures were assessed (room temperature and 40 °C). The compressive and flexural strength of glass wool after three days at 40 °C was 34.7 and 8.7 MPa respectively, compared to values of 29.1 and 9.3 MPa for stone wool. After 3 days at room temperature, the strengths were not measurable, however, after 28 days the respective compressive and flexural strength were 29.9 and 14.4 MPa in the case of glass wool, and 40.6 and 14.9 MPa for stone wool.