The preparation and characterization of low-temperature foams based on the alkali activation of waste stone wool. Issue 12 (15th June 2022)

• Record Type: Journal Article
• Authors: Pavlin, Majda; Horvat, Barbara; Češnovar, Mark; Ducman, Vilma
• Is Part Of: Ceramics international. Volume 48:Issue 12(2022)
• Page Start: 17668
• Page End: 17681
• Publication Date: 2022-06-15
• Subjects: Waste mineral wool -- Alkali-activated foams -- Porosity -- Mechanical properties -- Thermal conductivity; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.03.037
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Waste mineral wool represents a huge amount of construction and demolition waste that is still not adequately returned into the value chain but needs to be landfilled. In the present study, waste stone wool (SW) was evaluated for the preparation of alkali-activated foams. For this purpose SW was milled and sieved below 63 μm, then the activator (sodium silicate) and different amounts of foaming agent (hydrogen peroxide, H2 O2 ), varying between 1 wt% and 3 wt%, were added to the slurry and cured in moulds at an elevated temperature (70 ° C) for three days. In this way, foamed, highly porous materials were obtained whose density and mechanical properties were influenced by the amount of foaming agent used. The densities obtained ranged between 1.4 and 0.5 g/cm 3, with corresponding mechanical properties of between 12.6 and 1.5 MPa and total porosities in the range 37.8–78.6%, respectively. In the most porous samples with the total porosity of 78.6%, a thermal conductivity of 0.092 W/(m∙K) was confirmed. The study confirmed the suitability of waste mineral wool (in our case SW) as a precursor for alkali-activated foams with potential use in the construction sector or other industrial applications. Highlights: Waste mineral stone wool was used as a precursor in alkali activated foaming process. Foams were obtained with density down to 0.5 g/cm 3 and mechanical properties 1.5 MPa. Pore size and their distribution significantly affect mechanical properties. Unreacted fibres positively affect the mechanical properties. Interconnected pores decrease the thermal conductivity.