Mineral wool is a commonly used insulation material, and during the construction and demolition of buildings, a lot of mineral wool waste is generated. Currently, most of the material ends up in a landfill. Recycling mineral wool waste is problematic due to the small weight and big volume that makes transport of material more difficult. Alkali activation technology seems to be a promising solution also for waste wool recycling. But mineral wool needs a higher temperature to achieve early strength, therefore suitable additives should be added, like blast furnace slag which is also a commonly used material for alkali-activation.
This study aimed to evaluate the influence of different slags on the mechanical strength and microstructural properties of alkali-activated products. After sorting and milling of waste wool, we obtained powdered materials with more than 90% of the amorphous phase that is suitable for the alkali-activation process. Various slags which differ in their origin (electric arc furnace steel slag, ladle furnace basic slag, ground granulated blast-furnace slag), as well as in their chemical and mineralogical composition were chosen as additives. Sodium water glass was used as an activator. All mixtures were cured at 40°C. Based on the mechanical properties and microstructural evaluation, the optimal ratio of slag/mineral wool has been estimated.
This study confirmed the potential of secondary use of mineral wool waste as well as blast furnace slags for different building/construction materials obtains through alkali activation technology.