Abstract
Despite mineral wool waste is only a small fraction of total construction and demolition waste (CDW) by mass, it requires large transportation and landfilling capacities due to its low bulk density, and its utilization remains low compared to other CDW types. It is essential to understand the physical and chemical properties of this waste fraction in order to utilize it, e.g. as fiber reinforcement in composites or as supplementary cementitious material. Here, we provide a chemical and physical characterization of 15 glass wool and 12 stone wool samples of different ages collected from various locations across Europe. In addition, the chemical compositions of 61 glass and stone wool samples obtained from the literature are presented. Glass wool samples show little variation in their chemical composition, which resembles the composition of typical soda-lime silicate glass. Stone wool presents a composition similar to basaltic glass but with variability between samples in terms of calcium, magnesium, and iron content. Potentially toxic elements, such as Cr, Ba, and Ni, are present in mineral wools, but in low concentrations (<0.2%). Both wool types contain organic resin, which may decompose into smaller molecular fragments and ammonia upon heating or contact with alkaline solution. Mineral wool wastes have relatively similar length and width distributions, despite the age and type of the mineral wool. Overall, both mineral wool waste types have homogenous chemical and physical properties as compared to many other mineral wastes which makes their utilization as a secondary raw material promising.
Highlights
The generation of construction and demolition waste (CDW) is a globally increasing problem because in a modern society, the average lifetime of a concrete building is only 40 years (Huuhka, 2016)
On landfills and waste management stations, sam pling was conducted from piles of mineral wool waste that had been exposed to the weather, typically for a long time
Glass wool compositions in this study (N = Glass wool compositions in the literature (N = 18)
Summary
The generation of construction and demolition waste (CDW) is a globally increasing problem because in a modern society, the average lifetime of a concrete building is only 40 years (Huuhka, 2016). The change in raw materials over time may affect the chemical composition of mineral wool products, even though the com positions are carefully controlled during the manufacturing process. The development of biosoluble stone wool fibers mainly involves changes in Al2O3 and SiO2 content (Guldberg et al, 2000) Another critical material property of mineral wool waste is fiber width and length (i.e., physical dimensions). After melting the mineral raw materials in the manufacturing process, the melt is fiberized, typi cally by a spinner wheel in the case of stone wool and by a spinning machine with more than 2,000 small holes in it in the case of glass wool (Kowatsch, 2010). The presence of organic components may, for example, affect the re actions involved in the cementitious binders significantly; the organic resin content and type should be monitored when using mineral wool waste as a secondary raw material. The fiber length and width of mineral wool samples are reported as analyzed via a fiber-imaging method based on ultra highdefinition (UHD) image analysis
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