1. Green transition in slovenian building and civil engineering industry : 10 years of research on alkali-activated materials and alkali-activated foamsBarbara Horvat, Branka Mušič, 2024, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje) Povzetek: The building and civil engineering industry yearly causes more than 40% of man-made CO2 and consumes raw materials for two-thirds of Mont Everest. To decrease the carbon footprint and consumption of raw materials, alkali-activated materials (AAMs) are researched as an alternative to conventional building and civil engineering products like cements, mortar, and ceramics. Ideally, locally available waste materials are used as ingredients: (i) as precursors that react with alkali and form an aluminosilicate network, and (ii) as fillers that get permanently encapsulated and safely stored in AAMs. The addition of gas bubbles and lightweight fillers transforms AAMs into alkali-activated foams and alkali-activated lightweight materials that have the potential to be used as thermal and acoustic insulation materials. Although AAMs are researched worldwide, this review focuses on the state-of-the-art localised solely to Slovenia, particularly on the materials and curing procedures used, as well as on the scientific contribution of the basic research. Besides, the year 2024 marks 10 years of research on alkali activation of raw and waste inorganic materials in Slovenia. Ključne besede: secondary raw material, alkali-activated material, alkali-activated foams, alkali, circular economy, microwave irradiation, mechanical strength Objavljeno v DiRROS: 12.03.2024; Ogledov: 554; Prenosov: 447 Celotno besedilo (84,58 MB) Gradivo ima več datotek! Več... |
2. Influence of ammonium polyphosphates and 2,4,6-triamino-1,3,5-triazine on the mechanical-physical properties of polyurethane and alkali-activated materialsBranka Mušič, Barbara Horvat, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: In building constructions, the tendency towards an ever-better material directs us to composite materials. In this work, we prepared an organic-organic and organic-inorganic composite material by incorporating fire retardants, ammonium polyphosphates, and 2,4,6-triamino-1,3,5-triazine, into a polyurethane network and an aluminosilicate network (ASN) of alkali-activated material. Polyurethane foams (PUR) are well-known materials that, due to their properties, such as low weight-to-strength ratio, low electrical and thermal conductivity, flexibility, and relatively simple preparation process, are used in various industries, also in the construction industry, e.g., for thermal insulation of windows and doors or fixing and sealing joinery. Opposite, the ASN of alkali-activated metakaolin, successfully paves the way for new applications, such as high-temperature protection. In this paper, these interactive properties of prepared composites are studied using thermal testing and mechanical analysis. It was found that inhibitors significantly increase the fire resistance of PUR systems while they slightly reduce the mechanical properties. Incorporating polymer flame retardant into ASN in building products, such as façade panels , can decrease the mechanical properties but can offer the non-flammable building envelope not get heated from burning surroundings, i.e., not becoming a convection heat source, but rather represent a fire-distinguisher for flammable materials. Ključne besede: flame retardants, polyurethane, alkali activated material, metakaolin, microwave irradiation, mechanical strength Objavljeno v DiRROS: 12.03.2024; Ogledov: 629; Prenosov: 466 Celotno besedilo (2,52 MB) Gradivo ima več datotek! Več... |
3. Waste rubber incorporated in the alkali-activated metakaolin’s aluminosilicate network enhanced by microwave irradiationBarbara Horvat, Branka Mušič, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: Building materials represent the possibility of prolonging the life of waste materials. The key is to ensure that the products are suitable for their function. So we activated metakaolin with the alkaline Na-silicate solution in the ratio that ensures the prevention of efflorescence and high mechanical strength (Horvat and Ducman, 2019). As the waste material (to be incorporated in the aluminosilicate network (ASN) of the alkali-activated metakaolin) ground waste rubber from electric cables was used in the preselected mass ratios. Its inclusion in products, like paving stones, can reduce stiffness, improve durability, dampen vibrations, and reduce road noise. The mechanical strengths of test samples with rubber present on the active surface or slightly below were higher compared to samples where rubber was encapsulated throughout the volume. Compressive strength was higher when samples were irradiated with low powers of microwaves while irradiation with higher powers led to the foaming of alkali-activated slurry. The encapsulation quality of the ground rubber was evaluated by SEM while the chemical influence on ASN was determined by EDS, FTIR, and XRD. Slipperiness change on the active surface of pavement stones proved that the addition of the ground rubber enhanced the walking safety of the product. Ključne besede: secondary raw material, alkali activated material, waste rubber, metakaolin, encapsulation of organic in inorganic material, microwave irradiation, mechanical strength Objavljeno v DiRROS: 12.03.2024; Ogledov: 888; Prenosov: 550 Celotno besedilo (13,99 MB) Gradivo ima več datotek! Več... |
4. 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: 530; Prenosov: 423 Celotno besedilo (1,28 MB) Gradivo ima več datotek! Več... |
5. Evaluation of fly ash-based alkali activated foams at room and elevated temperaturesKatja Traven, Mark Češnovar, Srečo D. Škapin, Vilma Ducman, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: Alkali activated materials (AAM) are, in their broadest classification, any binder systems derived by the reaction of an alkali metal source (silicates, alkali hydroxides, carbonates , sulphates) with a solid, amorphous alumosilicate powder (found in precursors such as slag, fly ash and bottom ash). A wide variety of products can be obtained by the alkali activation process and could replace traditional construction products. Among the se, alkali activated foams (AAF) represent one of the most promising materials, owing to their economically accessible alumosilicate rich source materials, including industrial waste materials, clean processing, higher added value and most importantly, pro ducts with competitive properties. In the present study, the properties of alkali activated fly ash - based foam materials were studied at room temperature as well as at elevated temperatures (up to 1200 °C ) in order to develop a durable material in terms o f mechanical properties and suitability for high temperature applications. Ključne besede: lightweight porous insulating material, alkali activated materials, microstructural analysis Objavljeno v DiRROS: 05.03.2024; Ogledov: 646; Prenosov: 471 Celotno besedilo (970,74 KB) Gradivo ima več datotek! Več... |
6. Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelopeBarbara Horvat, Nataša Knez, Uroš Hribar, Jakob Koenig, Branka Mušič, 2024, izvirni znanstveni članek Povzetek: Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties. Ključne besede: waste polyurethane foam, polymeric flame retardants, alkali activated material, metakaolin, microwave irradiation, thermal-fire behaviour, mechanical strength Objavljeno v DiRROS: 01.03.2024; Ogledov: 947; Prenosov: 890 Celotno besedilo (29,74 MB) Gradivo ima več datotek! Več... |
7. PUR in geopolymerBarbara Horvat, Nataša Knez, Uroš Hribar, Jakob Koenig, Branka Mušič, 2024, zaključena znanstvena zbirka raziskovalnih podatkov Povzetek: The dataset supports the results shown in the tables and figures in the article entitled “Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelope” (doi: 10.1016/j.jclepro.2024.141387). It contains measurements of fire-behaviour characteristics, thermal conductivity, the behaviour of the material in the electromagnetic field in relation to the frequency, mechanical and structural evaluation, as well as chemical and mineralogical analysis. Ključne besede: measurements, waste polyurethane foam, polymeric flame retardants, alkali activated material, metakaolin, microwave irradiation, thermal-fire behaviour, mechanical strength Objavljeno v DiRROS: 20.02.2024; Ogledov: 806; Prenosov: 302 Raziskovalni podatki (2,51 MB) Gradivo je zbirka in zajema 1 gradivo! |
8. Fibre reinforced alkali-activated rock woolMajda Pavlin, Barbara Horvat, Vilma Ducman, 2022, objavljeni znanstveni prispevek na konferenci Povzetek: Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-time runs out due to its small density leading to large volume consumption during transport and in landfills where it usually ends. Because rock wool is mineralogically and chemically a promising precursor material for alkali-activation, it was milled from few centimetres-decimeters long fibres to micron-sized fibres. Since fibres in alkali-activated materials generally show an increase in mechanical strength, especially the bending strength, 1 m% of additional fibres (basalt, cellulose (2 types), glass, polypropylene, polyvinyl alcohol and steel fibres) was used in the alkali mixture, that was curred at 40 °C for 3 days. Time dependence of the mechanical strengths of alkali- activated materials with and without additional fibres was followed. Maximal increase of compressive and bending strength after 28 days was reached with polypropylene fibres, i.e. it was 20% and 30% higher than compressive and bending strength of alkali- activated material without additional fibres respectively. Ključne besede: secondary raw material, alkali activated material, foaming, homogenization, mechanical strength Objavljeno v DiRROS: 21.12.2023; Ogledov: 638; Prenosov: 269 Celotno besedilo (8,39 MB) Gradivo ima več datotek! Več... |
9. Influence of homogenization of alkali-activated slurry on mechanical strengthBarbara Horvat, Mark Češnovar, Katja Traven, Majda Pavlin, Katja Koenig, Vilma Ducman, 2022, objavljeni znanstveni prispevek na konferenci Povzetek: Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost- effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali- activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and different drying methods (drying at room temperature, drying at 105 °C). The viscosity of the slurry before homogenization was higher than after homogenization, the distribution of elements was more uniform and the compressive strength higher in all homogenized alkali activated materials, regardless of other parameters. Ključne besede: secondary raw material, alkali activated material, foaming, homogenization, mechanical strength Objavljeno v DiRROS: 21.12.2023; Ogledov: 598; Prenosov: 256 Celotno besedilo (15,82 MB) Gradivo ima več datotek! Več... |
10. 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: 619; Prenosov: 307 Celotno besedilo (1000,34 KB) Gradivo ima več datotek! Več... |