21. Preparation of façade panels based on alkali-activated waste mineral wool, their characterization and durability aspectsMajda Pavlin, Barbara Horvat, Vilma Ducman, 2022, original scientific article Abstract: Mineral wool is a widely used insulation material and one of the largest components of construction and demolition waste, yet it mainly ends up in landfills. In this work, we explored the potential recycling of waste stone wool in the pilot production of alkali-activated façade panels. The current work shows mechanical properties, SEM-EDS and mercury intrusion porosimetry analyses for three different mix designs used for the preparation of façade panels. They are all composed of waste stone wool and differ in the amount of co-binders (local slag, lime, metakaolin and/or fly ash) selected by the preliminary studies. In this study, co-binders were added to increase early strength and improve the mechanical properties and freeze-thaw resistance. The mechanical properties of each were measured up to 256 days, different durability tests were executed, and, by evaluating the mechanical properties, microstructure and workability of the mortar, the most suitable mix was selected to be used for pilot production. In addition, the leaching test of the selected mixture showed no exceeded toxic trace elements and therefore got classified as non-hazardous waste after its use.
Keywords: alkali activation, waste mineral wool, SEM, XRF, XRD, mechanical strength
Published in DiRROS: 19.06.2023; Views: 333; Downloads: 146
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22. The preparation and characterization of low-temperature foams based on the alkali activation of waste stone woolMajda Pavlin, Barbara Horvat, Mark Češnovar, Vilma Ducman, 2022, original scientific article 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, H2O2), 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/cm3, 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.
Keywords: alkali activation, waste mineral wool, mechanical strength, open access, alkalijska aktivacija, odpadna volna, SEM, XRF, XRD, mehanska trdnost, odprti dostop
Published in DiRROS: 19.06.2023; Views: 268; Downloads: 208
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23. Clay rich river sediments calcined into precursors for alkali activated materialsLea Žibret, Wolfgang Wisniewski, Barbara Horvat, Mojca Božič, Boštjan Gregorc, Vilma Ducman, 2023, original scientific article Abstract: Alkali activated materials (AAMs), a potential alternative to cement-based products or ceramics, can incorporate large amounts of currently landfilled aluminosilicate rich materials such as calcined clay-rich river sediments collected at hydropower plant dams. Untreated fresh sediment and untreated aged sediment intended to serve as AAM precursors were calcined to increase their amorphous content, then activated by Na or K-based silicate or hydroxide solutions and cured at 60 ◦C for three days.
Up to 30 mass % (ma%) of fly ash (FA) or ladle slag (LS) increased the mechanical performance. The phase composition and microstructure are analyzed using X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and mercury intrusion porosimetry to gain further insight into how the additives influence the final properties of the resulting AAMs. The main crystalline components of the prepared AAMs are quartz, illite/muscovite and feldspar. The amorphous content reaches up to 52.5 ma% in the Na-activated AAMs and up to 48.8 ma% in K-activated AAMs. The acquired results confirm the suitability of the investigated sediments as sole precursors for AAMs. The mechanical properties of the AAMs can be improved by adding FA and/or LS.
Keywords: sediments, alkali activated materials, properties
Published in DiRROS: 30.05.2023; Views: 317; Downloads: 249
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