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Abstract: 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.
Keywords: alkali activation, waste mineral wool, mechanical strength
Published in DiRROS: 31.07.2023; Views: 233; Downloads: 221
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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: 306; Downloads: 134
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Abstract: In the present study, four different locally available waste glass materials (bottle glass-BG, glass wool-GW, stone wool-SW and cathode-ray tube glass-CRTG) were treated with hot concentrated potassium hydroxide (KOH) in order to obtain alternative alkali activators (AAAs). We evaluated the suitability of the solutions obtained for use as AAAs in the production of AAMs. AAMs were prepared using electric arc furnace slag and selected AAAs with a higher content of dissolved Si. We evaluated the performance of the AAMs in comparison to that of slags activated with KOH or potassium-silicate (K-silicate). The compressive strength of the AAMs prepared with KOH-based AAAs were high when Si and Al were simultaneously abundant in the AAA (9.47 MPa when using the activator sourced from the CRTG), and low with the addition of KOH alone (1.97 MPa). The AAM produced using commercial K-silicate yielded the highest compressive strength (27.7 MPa). The porosity of the KOH-based AAM was lowest when an alternative BG-based activator was used (24.1%), when it was similar to that of the AAM prepared with a K-silicate. The BG-based activator had the highest silicon content (33.1 g/L), and NMR revealed that Si was present in the form of Q0, Q1 and Q2. The concentrations of toxic trace elements in the AAAs used for alkali activation of the slag were also determined, and leaching experiments were performed on the AAMs to evaluate the immobilisation potential of alkali-activated slag. In the SW AAAs the results show acceptable concentrations of trace and minor elements with respect to the regulations on waste disposal sites, while in the activators prepared from BG, CRTG and GW some elements exceeded the allowable limits (Pb, Ba, Sb, and As).
Keywords: alkali activated materials/geopolymers, alternative activators, NMR, leaching
Published in DiRROS: 08.06.2023; Views: 302; Downloads: 195
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Published in DiRROS: 14.03.2023; Views: 540; Downloads: 181
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Abstract: Pljučnica je najpogostejši vzrok za težji potek okužbe z virusom SARS-CoV-2 in s hospitalizacijo. Potek covidne pljučnice je lahko različen; infiltrati, vidni na rentgenski sliki, se lahko resorbirajo spontano, včasih pa je potrebno zdravljenje s sistem-skimi glukokortikoidi. Ob odpustu iz bolnišnice zdravljenje običajno še ni končano, zato je Združenje pulmologov Slovenije v želji po enotnem obravnavanju bolnikov s covidno pljučnico izdelalo mnenje za obravnavo in sledenje bolnikov po od-pustu iz bolnišnice. Zavedamo se, da ob novi bolezni ne gre za dokončno priporočilo, saj bodo nova spoznanja o covidni pljučnici zanesljivo zahtevala obnavljanje priporočil.
Keywords: covid-19, mnenja, pljučnica, pulmologija, sistemski glukokortikoidi, covidna pljučnica
Published in DiRROS: 15.12.2021; Views: 1093; Downloads: 200
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