1. Analysis of alkali-activated mineral wool-slag binders : evaluating the differences between one-part and two-part variationsElijah Adesanya, Rawia Dabbebi, Christine Rößler, Majda Pavlin, Zhenming Li, Tero Luukkonen, Juho Yliniemi, Mirja Illikainen, 2024, izvirni znanstveni članek Povzetek: Two synthesis pathways (one- and two-part) in alkali-activated binders were compared using ground granulated blast furnace slag (GGBFS), mineral wool (MW) activated using dry and liquid alkali activators with similar Na2O/SiO2 modulus. The effect of activator type on reaction kinetics, strength development, setting times, and durability shows that one-part synthesis does not only improve early strength, but also provide better durability properties. While the highest compressive strength (56 MPa, 90 days) was achieved for the one-part mix (DM), the reaction products (presence of Mg–Al layered double hydroxide and C–S–H-like phases) observed for both mortar mixes were similar. The DM mortars showed better resistance to sulfate attack than two-part mix (WM) mortars and sets faster. The results highlight the significance of the one-part pathways in the synthesis of alkali-activated materials.
Ključne besede: recycling, alkali activated material, mineral wool
Objavljeno v DiRROS: 11.03.2024; Ogledov: 107; Prenosov: 77
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2. Pilot production of façade panels : variability of mix designMajda Pavlin, Barbara Horvat, Vilma Ducman, 2023, objavljeni znanstveni prispevek na konferenci Povzetek: As part of the WOOL2LOOP project, the Slovenian National Building and Civil Engineering Institute (ZAG), in collaboration with Termit d.d. were responsible for the production of façade panels. An initial mix design was developed at ZAG, where alkali-activated façade panels were produced, primarily from stone wool waste, while production took place at Termit. The mix design was changed twice during the pilot production, before a final product with suitable durability was developed. A compressive strength of up to 60 MPa and bending strength of approximately 20 MPa was achieved. The mechanical properties, however, varied, due to the unevenly milled batches of the milled mineral wool. Milling on a larger scale is very challenging, and it is difficult to obtain consistent quality of the milled material. Once the correct curing process had been found, however, the panels produced showed good performance. Moreover, the results from leaching tests showed that the elevated concentrations of certain elements (Cr, As and Mo) did not exceed the legal limits for non- hazardous waste.
Ključne besede: waste mineral wool, alkali activated material, façade panels, pilot production, circular economy
Objavljeno v DiRROS: 28.11.2023; Ogledov: 272; Prenosov: 102
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3. Production of lightweight alkali activated mortars using mineral woolsAhmad Alzaza, Mohammad Mastali, Paivo Kinnunen, Lidija Korat, Zahra Abdollahnejad, Vilma Ducman, Mirja Illikainen, 2019, izvirni znanstveni članek Povzetek: This experimental study aimed to develop a fiber-reinforced lightweight mineral wool-based alkali activated mortar. The lightweight mineral wool-based alkali activated mortars were produced using premade foam and reinforced by polypropylene (PP) fibers. They were assessed in terms of fresh and hardened-state properties. Fresh-state properties were investigated by mini-slump tests. Hardened-state characteristics were assessed by ultrasonic pulse velocity, dry density, compressive and flexural strengths, drying shrinkage, efflorescence, water absorption, and permeable porosity. For the first time, the resistance of the synthesized lightweight mineral wool-based alkali activated mortars against harsh conditions (carbonation, freeze and thaw, and high temperature) were evaluated. The porous structures of the developed lightweight alkali activated mortars were also analyzed using an X-ray micro-computed tomography (CT) technique. Lightweight mix compositions with densities in a range of 770%1510 kg/m3, compressive strengths of 1%9 MPa, and flexural strengths of 2.6%8 MPa were developed. Increases in both density and strength after carbonation were also recorded, while a decrease of strength was noticed after exposure to freeze/thaw and high temperatures of up to 500 %C.
Ključne besede: alkali activation, mineral wool, mortars
Objavljeno v DiRROS: 24.10.2023; Ogledov: 327; Prenosov: 130
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4. Mechanical, microstructural and mineralogical evaluation of alkali-activated waste glass and stone woolMajda Pavlin, Barbara Horvat, Ana Frankovič, Vilma Ducman, 2021, izvirni znanstveni članek Povzetek: Mineral waste wool represents a significant part of construction and demolition waste (CDW) not yet being successfully re-utilized. In the present study, waste stone wool (SW) and glass wool (GW) in the form received, without removing the binder, were evaluated for their potential use in alkali activation technology. It was confirmed that both can be used in the preparation of alkali-activated materials (AAMs), whether cured at room temperature or at an elevated temperature in order to speed up the reaction. The results show that it is possible to obtain a compressive strength of over 50 MPa using SW or GW as a precursor. A strength of 53 MPa was obtained in AAM based on GW after curing for 3 days at 40 °C, while a similar compressive strength (58 MPa) was achieved after curing the GW mixture for 56 days at room temperature. In general, the mechanical properties of samples based on GW are better than those based on SW. The evolution of mechanical properties and recognition of influential parameters were determined by various microstructural analyses, including XRD, SEM, MIP, and FTIR. The type of activator (solely NaOH or a combination of NaOH and sodium silicate), and the SiO2/Na2O and liquid to solid (L/S) ratios were found to be the significant parameters. A lower SiO2/Na2O ratio and low L/S ratio significantly improve the mechanical strength of AAMs made from both types of mineral wool.
Ključne besede: alkali activation, waste mineral wool, mechanical strength
Objavljeno v DiRROS: 31.07.2023; Ogledov: 244; Prenosov: 235
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5. Preparation of façade panels based on alkali-activated waste mineral wool, their characterization and durability aspectsMajda Pavlin, Barbara Horvat, Vilma Ducman, 2022, izvirni znanstveni članek Povzetek: 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.
Ključne besede: alkali activation, waste mineral wool, SEM, XRF, XRD, mechanical strength
Objavljeno v DiRROS: 19.06.2023; Ogledov: 317; Prenosov: 141
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6. 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, izvirni znanstveni članek Povzetek: 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.
Ključne besede: alkali activation, waste mineral wool, mechanical strength, open access, alkalijska aktivacija, odpadna volna, SEM, XRF, XRD, mehanska trdnost, odprti dostop
Objavljeno v DiRROS: 19.06.2023; Ogledov: 265; Prenosov: 205
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