1. Why geopolymers and alkali-activated materials are key components of a sustainable world : a perspective contributionWaltraud M. Kriven, Cristina Leonelli, John L. Provis, Aldo R. Boccaccini, Cyril Attwell, Vilma Ducman, Claudio Ferone, Sylvie Rossignol, Tero Luukkonen, Jannie S. J. Van Deventer, José V. Emiliano, Jérôme E. Lombardi, 2024, original scientific article Abstract: This perspective article delves into the transformative potential of alkali-activated materials, acid-activated materials, and geopolymers in mitigating climate change and market challenges. To harness the benefits of these materials, a comprehensive strategy is proposed. This strategy aims to integrate these materials into existing construction regulations, facilitate certification, and promote market access. Emphasizing research and innovation, the article advocates for, increased funding to refine the chemistry and production of these materials, prioritizing low-cost alternatives and local waste materials. Collaboration between academia and industry is encouraged to expedite technological advances and broaden applications. This article also underscores the need to develop economic and business models emphasizing the long-term benefits of these materials, including lower life-cycle costs and reduced environmental impact. Incentivizing adoption through financial mechanisms like tax credits and subsidies is suggested. The strategy also includes scaling up production technology, fostering industrial collaboration for commercial viability, and developing global supply chains. Educational programs for professionals and regulators are recommended to enhance awareness and adoption. Additionally, comprehensive life-cycle assessments are proposed to demonstrate environmental benefits. The strategy culminates in expanding the applications of these materials beyond construction, fostering international collaboration for knowledge sharing, and thus positioning these materials as essential for sustainable construction and climate change mitigation.
Keywords: geopolymers, alkali activated materials, perspective
Published in DiRROS: 15.04.2024; Views: 113; Downloads: 63
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2. Characterization and Mechanical Properties of Sintered Clay MineralsSara Tominc, Vilma Ducman, Jakob Koenig, Srečo D. Škapin, Matjaž Spreitzer, 2024, published scientific conference contribution Abstract: The need to reduce energy consumption and the carbon footprint generated by firing ceramics has stimulated research to develop sintering processes carried out at lower temperatures(ideally not above 300 °C) and high pressures (up to 600 MPa), the so-called cold sintering process (CSP) (Grasso et al., 2020, Maria et al., 2017). To evaluate the applicability of CSP to clays, we focused on two representative clay minerals, kaolinite and illite, and on the natural clay material obtained from a Slovenian brick manufacturer. The selected clay materials were characterized on the basis of mineralogical-chemical composition (XRD, XRF) and particle size distribution (SEM analysis, PSD, BET). The powders of clay minerals and natural clay material were first sintered in a heating microscope to determine the sintering conditions and then in a laboratory furnace at 1100 °C for 2 hours and additionally at 1300 °C for kaolinites. The effect of compression of the initial powders on their final properties was also investigated.
Keywords: conventional sintering, cold sintering, clay minerals, characterization, mechanical properties
Published in DiRROS: 29.03.2024; Views: 128; Downloads: 57
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3. Innovative pre-fabricated components including different waste construction materials reducing building energy and minimising environmental impacts (InnoWEE)Elena Loredana Fodor, Vilma Ducman, Giovanni Ferrarini, Sergio Tamburini, Constantinos Tsoutis, Francesca Becherini, Antonio Garrido-Marijuán,, Giulia Mezzasalma, Leonardo Rossi, Emil Lezak, Adriana Bernardi, 2019, published scientific conference contribution Abstract: InnoWEE is a four-year project (from 2016 to 2020) financed by the European Community that involves ten partners from different European countries, as Greece, Italy, Belgium, Romania, Slovenia, Spain and Poland. The aim is to use the waste materials coming from construction and demolition processes of buildings and include them into a geopolymeric matrix with the purpose of producing prefabricated panels for different applications. Construction and demolition waste (CDW) materials with suitable characteristics have been selected to develop high performance geopolymeric panels for building walls envelopes and radiant panels for indoor walls and ceilings with low environmental impact. Field tests will be carried out in different sites in Europe characterized by different climatic conditions to check the simplicity of the installation procedure and the performance of the panels in terms of energy efficiency and environmental impact.
Keywords: prefabriced elements, geopolymers, CDW
Published in DiRROS: 08.03.2024; Views: 107; Downloads: 56
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4. Evaluation of fly ash-based alkali activated foams at room and elevated temperaturesKatja Traven, Mark Češnovar, Srečo D. Škapin, Vilma Ducman, 2020, published scientific conference contribution Abstract: 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.
Keywords: lightweight porous insulating material, alkali activated materials, microstructural analysis
Published in DiRROS: 05.03.2024; Views: 106; Downloads: 45
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5. Foundry wastes as a potential precursor in alkali activation technologyBarbara Horvat, Alenka Sešek Pavlin, Vilma Ducman, 2020, published scientific conference contribution Abstract: In this study the amount of amorphous phase of elements useful in alkali activation of waste materials produced by the foundry industry was determined. Waste foundry sands, foundry flue gas and waste casting cores were alkali activated, and waste green ceramics and bottom ash were added to one of the foundry sand samples to shorten the time for producing measurable compressive strength from 1.5 years to 1 week.
Keywords: alkali activated materials, foundry wastes, compressive strength, upcycling, circular ecnomy
Published in DiRROS: 01.03.2024; Views: 133; Downloads: 62
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6. The deformation of alkali-activated materials at different curing temperaturesMark Češnovar, Katja Traven, Vilma Ducman, 2020, published scientific conference contribution Abstract: Alkali activation is a chemical process whereby materials rich in aluminosilicate, which dissolves in basic media at room temperature, form binding phases by polycondensation. The alkali- activated materials (AAM) are a promising alternative to binding materials such as cement or other products in civil engineering (van Deventer et al., 2012). This study investigates the early age shrinkage behavior of Slovenian ladle and electric arc furnace slag - based alkali activated materials at different curing temperatures. The dimensions of specimens cured at room temperature and elevated temperatures up to 90 °C were measured over the first 7 hours (every 10 min). The results show that the most shrinkage occurred at the highest temperature, owing to the highest rate of evaporation of liquid content. Loss of mass follows from the drying shrinkage.
Keywords: alkali activated materials, shrinkage, compressive strength
Published in DiRROS: 01.03.2024; Views: 127; Downloads: 86
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7. The influence of different fibres quantity on mechanical and microstructural properties of alkali-activated foamsKatja Traven, Mark Češnovar, Barbara Horvat, Vilma Ducman, 2022, published scientific conference contribution Abstract: Alkali activated foams (AAFs) were produced using electric arc furnace steel slag (EAF) and ladle furnace basic slag (LS), obtained from two metallurgical companies in Slovenia. They were activated with a mixture of sodium water glass (Na2SiO3) and solid NaOH and foamed with hydrogen peroxide (H2O2). Pores were stabilized with the addition of Triton as a surfactant. Four types of fibres were added to the studied mixture (polypropylene (PP), polyvinyl-alcohol (PVA), basalt (B), and glass wool (GW)) in five different quantities: 0.5, 1.0, 1.25, 1.5 and 2.0 vol % in order to additionally stabilize the structure and thus improve its mechanical properties. The results of mechanical properties showed, that compressive strength was increased in all 20 specimens, partially due to the increased density as well as to the fibre addition. Flexural strength on the other hand was the most improved in the samples where PP and PVA fibres were added. The samples with the addition of B and GW fibres on the other hand showed only small or no improvement in flexural strength in comparison to the referenced sample. Additionally, the microstructure of used fibres and selected foams was also investigated by the means of SEM analysis.
Keywords: fibers, alkali activated foams, properties
Published in DiRROS: 31.01.2024; Views: 149; Downloads: 62
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8. Characterisation of a 3D-printed alkali-activated material based on waste mineral wool at room and elevated temperaturesMajda Pavlin, Barbara Horvat, Romana Cerc Korošec, Rok Capuder, Lidija Korat, Vilma Ducman, 2024, original scientific article Keywords: recycling, alkalijsko aktivirani materiali, 3D print, mineralna volna
Published in DiRROS: 25.01.2024; Views: 237; Downloads: 115
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9. Alternative alkali activators based on waste bottle glass and waste cathode-ray tube glassKatja Koenig, Katja Traven, Vilma Ducman, 2021, published scientific conference contribution Abstract: Alkali-activated binders are an environmentally friendly alternative to Portland cement, particularly when locally-available raw materials are used. It is well known that alkali activation with a sodium silicate activator generates a hardened binder with higher compressive strength than a binder hardened with sodium hydroxide. As the alkali-silicate activators are produced through energy extensive processes, and their use can significantly increase the carbon footprint of the final products, it is of great significance to develop alternative alkaline activators based on locally-available waste materials. This article assesses the potential to apply waste bottle glass and waste cathode-ray tube (CRT) glass to synthesise alternative alkali activators by the hydrothermal method. Inductively coupled plasma-optical emission spectrometry (ICP-OES) was used to determine silicon and aluminium content in the alternative activators. The influence of dissolution process parameters (time, temperature, particle size) on the concentrations of silicon and aluminium in the alternative activators was investigated. The alternative activators with silicon concentration up to 19 g/L and aluminium concentration up to 0.9 g/L were prepared at T = 120 °C and boiling time 24 h. The alternative alkali activators and, for comparison, also commercial sodium silicate were used in the alkali activation of fly ash powder. The formed pastes were cured at 70 °C for 72 h. Mechanical strength measurements indicated that alkali activation of fly ash with the optimal alternative activator yielded hardened paste with compressive strength of 33 MPa. However, the compressive strength of hardened paste prepared from fly ash and commercial sodium silicate reached 70 MPa. Part of this difference can be ascribed to the lower density of hardened pastes prepared with alternative activators.
Keywords: alkali -activated materials, alternative alkali activators, waste bottle glass, waste cathode -ray tube glass, fly ash, hydrothermal method
Published in DiRROS: 25.01.2024; Views: 171; Downloads: 113
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10. Influence of curing / drying methods including microwave heating on alkali activation of waste casting coresBarbara Horvat, Vilma Ducman, 2021, published scientific conference contribution Abstract: Within previous investigation alkali activation of waste casting cores at room temperature did not give promising results, i.e. when the precursor was gently ground and sieved below 600 %m the alkali activated material fell apart at demolding, and when the precursor was ground below 90 %m, the alkali activated material did not solidify in more than 2 years. , Therefore different drying/curing methods were applied to enhance the reaction. Waste casting cores were prepared in two granulations (sieved below 600 %m and below 90 %m), activated with Na -water glass and 10 M NaOH, cured at different temperatures (70 °C and room temperature), and subsequently cured/dried at three different conditions: room temperature, 110 °C, and irradiated with microwaves. The highest compressive strength, 25 MPa, was gained with subsequent curing/drying at 110 °C. The lowest density, 0.5 kg/l, with compressive strength above 3 MPa, was achieved with subsequent curing/drying with microwaves .
Keywords: waste casting cores, alkali activation, curing, drying, microwaves, mechanical strength
Published in DiRROS: 22.01.2024; Views: 206; Downloads: 105
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