A circular approach to stone wool: Alkali-activated lightweight aggregates

This study investigates the high-value recycling of stone wool from construction and demolition waste into alkali-activated lightweight insulation aggregates, designed for ground cover insulation. Various proportions of milled and as-is stone wools are alkali-activated to produce aggregates. The aggregates demonstrate loose bulk densities ranging from 720 to 850 kg m⁻³ and dry thermal conductivity from 0.075 to 0.094 W m⁻¹·K⁻¹, with moderate water sorption capacities. The fibre morphology of as-is stone wool influences rheology, introducing a greater number of pores or defects, which results in a decrease in mechanical strength. Hydrothermal simulations reveal that the floor assembly of the rehabilitated crawl space, partially filled with the fabricated aggregates, shows a reduction in water content and an increase in floor surface temperature. This observation suggests potential benefits for maintaining the structural integrity of buildings and enhancing occupant comfort.