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  • 1.
    Kothari, Ankit
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Skanska Teknik AB, Skanska Sverige AB, 40518 Göteborg, Sweden.
    Ellison, Tommy
    BESAB AB, Technical Manager, Berg & Betong, Tagenevägen 7, 42259 Hisings Backa, Göteborg, Sweden.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Partial replacement of OPC with CSA cements – effects on hydration, fresh-, hardened-properties2023In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 35, no 5, p. 207-224Article in journal (Refereed)
    Abstract [en]

    The effects of a partial replacement of Ordinary Portland cement (OPC) with three types of calcium sulfoaluminate (CSA) cements (40 wt% and 20 wt%) were investigated. The obtained results were generally in agreement with previously published data but with few interesting exceptions. Setting times were shortened due to the formation of ettringite. The maximum hydration temperature increased for concretes containing 40 wt% of CSA but decreased when 20 wt% replacement was used. The decrease was related to the deficiency of the available sulfates, which limited the formation of ettringite. The presence of extra anhydrite and calcium oxide was associated to the delayed establishment of the second temperature peak in contrast to OPC-based concretes. Their surplus delayed calcium aluminate and belite reactions, and triggered renewed formation of ettringite, C-S-H and portlandite. Effects of aluminum hydroxide were also indicated as possibly important, although not proved experimentally in this research. The slightly lower compressive strength measured for mixes containing 40 wt% of CSA were linked with more formed ettringite. The same factor was indicated as the key to the reduction of the total shrinkage in mixes containing 40 wt% of CSA and increased for the lower CSA replacement level. In that case, the insufficient amount of formed ettringite caused too small expansion, which could not efficiently mitigate or compensate the developed shrinkage.

  • 2.
    Rajczakowska, Magdalena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Skanska Sverige AB, 40518 Göteborg, Sweden.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Autogenous self-healing of low embodied energy cementitious materials: Effect of multi-component binder and crack geometry2023In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 376, article id 130994Article in journal (Refereed)
    Abstract [en]

    Concrete's ability to auto-repair the cracks reduces the need for maintenance and repair. Autogenous self-healing is an intrinsic property of concrete highly dependent on the binder composition. The urgent necessity to decrease CO2 emissions of concrete by replacing cement with “greener” materials provides challenges and opportunities for self-healing cementitious materials. This research aims to verify the self-healing behavior of environmentally friendly multi-component binders. An experimental study is conducted to test the effect of binder composition-related parameters (e.g., phase composition, porosity) and crack geometry on the self-healing efficiency of the “green” mortars. Cementitious materials with 50 wt.%cement replacement with limestone powder blended with fly ash, blast furnace slag, and silica fume are investigated. Sorptivity change, compressive strength regains, and crack closure after self-healing are used to quantify the self-healing efficiency. Quantitative analysis and correlations between chemical composition/microstructural features, geometrical crack characteristics, and self-healing measures are investigated. The results indicate that “green” binder composition affects the self-healing mechanism leading to different levels of performance recovery. Some SCMs-limestone binder formulations enable a better self-healing efficiency than pure OPC or OPC/limestone cementitious materials, presumably due to a synergistic effect between the limestone and the mineral additions. Correlation analysis indicated that geometrical complexity characterized by fractal dimension and tortuosity of the crack does not affect the external crack closure, whereas the fractal dimension and maximum crack width are correlated with the internal crack healing.

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  • 3.
    Rothhämel, Mirja
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Cement-CKD stabilized sandy clayey silt soil with sulfide contents exposed to freezing and thawingIn: ISSN 0165-232XArticle in journal (Refereed)
  • 4.
    Rothhämel, Mirja
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Mácsik, Josef
    Ecoloop AB, Stockholm, Sweden.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stabilization of sulfide soil with by-product originated hydraulic binder in a region with seasonal frost - a field investigation2022In: Transportation Geotechnics, ISSN 2214-3912, Vol. 34, article id 100735Article in journal (Refereed)
    Abstract [en]

    Fine-grained soils often show a low bearing capacity as well as a high frost susceptibility. These aspects are a challenge for the needs of infrastructure. The addition of hydraulic binder to fine-grained soils is common worldwide to improve the soil properties for engineering purposes. The classical hydraulic binders are lime and cement, but nowadays more and more by-producs are used as well like e. g. fly ash, slag or filter dust. The binders are called “hydraulic” because they react with water. By this reaction new minerals are formed, connecting the soil particles together. This improves the properties of the soil: A strength increase is even visible when the curing takes place in cold environment or after freezing and thawing cycles. Another challenge that occurs in fine-grained sulfidic soils is their possible acidification, when aerated due to e. g. excavation or drainage. Sulfide minerals in contact with oxygen produce sulfuric acid. The low pH caused by this oxidation can mobilize metals from the soil minerals, with harmful consequences for the environment. The addition of lime or calcite is one possible action to improve acid sulphate soils for agricultural and aqua-cultural purposes. The high pH of the lime and calcite increases the buffer capacity of the soil. However, the addition of hydraulic binder to a fine-grained sulfide soil in order to improve both the engineering properties and to buffer the potential acidification is sparsely investigated. In the present publication a field investigation is described where a cement mixture with cement kiln dust (CKD) is used alone and in combination with a calcite-rich by-product from the paper industry to improve a fine-grained sulfide soil for possible usage in earthworks. Samples taken from the surface after one year show a buffering of the potential acidification. Additionally, a strength increase can be seen in the stabilized soil when compressed and stored in a tube in field conditions.

  • 5.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Mechanical activation of clay: a novel route to sustainable cementitious binders2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    EU Sustainable Development Strategy planned to achieve improvement of life-quality by promoting sustainable production and consumption of raw materials. On November 2018, EU Commission presented a long-term strategy, aiming among others a climate-neutral economy by 2050. Cement production is contributing to 6-10% of the anthropogenic CO2 emissions. Thus, several strategies for total or partial replacement of Portland cement in concrete production have been developed. The use of supplementary cementitious materials (SCM) and alkali-activated materials (AAM) is considered the most efficient countermeasure to diminish CO2 emissions. The broadening of knowledge with particular attention to the sustainable goals is the primary requirement to be fulfilled when novel materials are investigated. This study aims to develop a novel clay-based binder that can be used as a sustainable alternative to produce SCM as well as AAM. Clay is a commonly occurring material, with large deposits worldwide. However, natural clay has a low reactivity and various compositions, depending, e.g. on the weathering conditions. The present research aims exactly at enhancing the reactivity of natural clays occurring in Sweden subjecting them to mechanical activation in a planetary ball mill. Ball milling (BM) is considered a clean technology able to enhance the reactivity of crystalline materials without resorting to high processing temperatures or additional chemicals. BM was able to induce amorphization in clay minerals and to transform the layered platy morphology to spherical shape particles. The efficiency of the process was strictly related to the used process parameters. Higher ball to processed powder (B/P) ratio, longer time of grinding and higher grinding speeds increased the degree of the obtained amorphization. However, an undesired extensive caking and agglomeration occurred in certain setups. The potential of activated clay as a SCM was investigated in specific case studies. The measured compressive strength results showed a direct correlation between the enhanced amorphization degree of the mechanically activated clay and the increased strength values. The pozzolanic activity was induced and enhanced after the mechanical activation of the clay. The reactivity was assessed by the strength activity index (SAI). Furthermore, preliminary tests have shown that the alkali activation of the processed clays produced solidified matrixes with considerable strength.

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  • 6.
    Tole, Ilda
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Revalorization of poorly reactive sources by mechanochemical activation: An alternative approach for sustainable cementitious binders2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The latest report from the Intergovernmental Panel on Climate Change made once again clear the urge to take immediate actions to reduce the emissions of carbon dioxide and other greenhouse gases. Among the UN Sustainable Development Goals (SDGs), Nr. 12 (“Ensure sustainable consumption and production of raw materials”) aims to improve the industrial sector and to ensure a high quality of life. Concrete is the second most used material after water and in its traditional form utilizes cement clinker, whose production contributes to 8-10% of the anthropogenic CO2 emissions. Among the strategies to diminish the CO2 footprint, use of supplementary cementitious materials (SCM) and alkali-activated materials (AAM) are currently considered the most efficient countermeasures.  

    Within this framework, revalorization of poorly reactive sources by mechanochemical activation can contribute to the development of novel binders with decreased CO2 footprint that can be utilized as partial or full replacement of Portland cement in concrete. Natural clays, mine tailings and air-cooled blast furnace slags (ACBFS), were activated in this study. Their applicability to be used in concretes as SCMs or/and AAMs was assessed. Natural clays are a mixture of various phases, whose compositions depends on weathering conditions. Naturally, they do not possess sufficient chemical reactivity to be utilized as SCMs. Similar properties possess mine tailings generated after extraction of precious elements, and slags produced in  blast furnaces of traditional steel plants.  

    The present study aims to enhance the reactivity of these resources through mechanochemical activation (MCA) in a planetary ball mill. The process is considered a clean technology able to enhance the reactivity of crystalline materials without resorting to high processing temperatures or additional chemicals. MCA can induce amorphization, destroying the structure and breaking the bonds within the aluminosilicates and other minerals structure. The chosen parameters in the ball mill, as i.e. the filling amount, time of grinding, or speed of rotation, are strictly related to the degree of amorphization. Longer time of grinding, higher ball to processed powder (B/P) ratio, and higher grinding speeds generally increased the degree of the obtained amorphization. In such regard, an optimized process was chosen and further utilized to process all the poorly reactive resources. After MCA, the potential of clays and tailings as a SCM was investigated, while ACBFS was investigated as a precursor for alkali-activated materials. The achieved mechanical properties indicated a direct correlation between the enhanced amorphization degree of the mechanically activated clay and the increased strength values. The evaluation of SCMs was done by testing of their pozzolanic reactivity, enhanced after the mechanochemical activation. The reactivity was assessed by the strength activity index (SAI) and the Frattini test. Clays with higher content of clay minerals and tailings from the Kiruna mine deposit in Sweden showed increased pozzolanic reactivity and a great potential to be utilized as partial replacement of cement in concrete production. Furthermore, preliminary tests have shown that the alkali activation of the processed ACBFS produced solidified matrixes with considerable mechanical properties.   

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  • 7.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Supplementary cementitious materials and mechanochemistry for sustainable concrete production2020In: 4th International Balkans Conference on Challenges of Civil Engineering: Abstract Book / [ed] Enea Mustafaraj, Julinda Keçi, Erion Luga, Tirana: Epoka University Press , 2020, p. 27-27Conference paper (Refereed)
    Abstract [en]

    Excavation and removal of unstable clayey soils before construction works, e.g., in infrastructure, residential or commercial buildings, etc., can generate vast amounts of waste clay deposits. Treatment of those clays to achieve suitable supplementary cementitious materials (SCMs) for use in concrete production can extensively contribute to a circular economy. Mechanical activation (MC) by ball milling has shown suitability to be an alternative and sustainable method to process clays and to obtain dehydroxylation at reduced temperatures and without the addition of chemicals. Furthermore, BM can induce amorphization, increased chemical reactivity, and improved pozzolanic properties. Amorphization of crystalline phases can be achieved also for poorly reactive materials such as air-cooled blast furnace slags (ACBFS), which can be further utilized as a precursor in sodium silicate alkali-activated systems. This study shows how mechanical activation is promoting the reactivity of clay and ACBFS, and their potential to be used as a replacement for cement in concrete production. Evaluation of the pozzolanic activity before and after treatment was performed for the treated clay, suggesting increased pozzolanic properties. While alkali-activated systems based on mechanically treated ACBFS reached, after 28 days, comparable compressive strength values with the commonly used ground granulated blast furnace slag (GGBFS) 

  • 8.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Delogu, Francesco
    Revalorization of mine tailings by mechanochemical activationManuscript (preprint) (Other academic)
  • 9.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Delogu, Francesco
    Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari, Italy.
    Qoku, Elsa
    School of Civil and Environmental Engineering, Georgia Tech,790 Atlantic Drive, Atlanta, GA 30332, Georgia.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Enhancement of the pozzolanic activity of natural clays by mechanochemical activation2022In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 352, article id 128739Article in journal (Refereed)
    Abstract [en]

    Replacement of cement with supplementary cementitious materials (SCMs) is a proven method to reduce clinker in cement and contribute to decreased CO2 emissions. Natural clays are commonly occurring materials that do not possess pozzolanic activity in their original state. Mechanochemical activation (MCA) can be an alternative and sustainable method to enhance their reactivity. In this study, the pozzolanic reactivity of three natural clays, originating from Sweden, was analyzed after the application of MCA in a planetary ball mill. Strength activity index (SAI), Frattini test, and conductivity test were used to evaluate the pozzolanic reactivity. All processed clays by MCA have achieved a SAI greater than 100%, while the Frattini test indicated an improved pozzolanic activity of samples containing a higher amount of clay minerals. The obtained results show that MCA could improve the pozzolanic reactivity, but the effect depends on the mineralogical composition and particle size of the clays.

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  • 10.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Mechanochemical activation of natural clay minerals: an alternative to produce sustainable cementitious binders – review2019In: Mineralogy and Petrology, ISSN 0930-0708, E-ISSN 1438-1168, Vol. 113, no 4, p. 449-462Article in journal (Refereed)
    Abstract [en]

    Mechanochemical activation can be defined as a process able to induce structural disorder through intensive grinding. In certain conditions, it may increase the chemical reactivity of the processed material. The process is extensively utilized in extractive metallurgy, synthesis of nanocomposites or pharmacology. It is also considered an environmentally friendly alternative to activate kaolinitic clay avoiding high calcination temperature. This paper aims to give a comprehensive overview of the process, its evolution, process parameters and applications. The paper focuses on the mechanochemical treatment of natural clay minerals, aiming at their transformation into cementitious or pozzolanic materials. It provides a summarized review of the theories related to the mechanochemistry and discusses commonly used models. The paper also analyzes various key factors and parameters controlling the mechanochemical activation process. The optimization and control of the several factors, as the filling ratio, the grinding media, the velocity, the time of grinding, etc., can promote developments and new research opportunities on different fields of application. Examples of applications, with a special focus on mechanochemically activated clay minerals and their use as cementitious binders, are listed as well.

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  • 11.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Mechanochemically activated clay as asustainable cementitious binder2019In: Proceedings ICSBM 2019: Volume - Greened Materials / [ed] V. Caprai; H.J.H. Brouwers, Technische Universiteit Eindhoven, 2019, Vol. 3, p. 462-468Conference paper (Refereed)
    Abstract [en]

    High-temperature requirements, emission of hazardous substances from cement kilns and the significant CO2 footprint in the calcination step are factors requiring special attention in the cement industry. Local and commonly occurring clays can be a sustainable alternative for producing cementitious binders. Structural disorder in natural clay minerals can be induced through mechanochemical activation (MCA), by which the material develops an enhanced reactivity. The treatment of a Swedish natural clay through intensive grinding is carried out in order to assess its potential as a sustainable cementitious binder. Several grinding parameters influence a MCA product. The filling ratio of the jar, the rotation speed, the time of grinding, as well as wet and dry environment, are variated to optimize the MCA process. The MCA process doesnot require high temperatures or added chemicals and shorter processing times can avoid high-energy requirements during fine grinding. The structural changes of the clay were analysed by X-Ray Diffraction (XRD). Analysis of the particle size distribution of the raw and processed clay suggested a correlation with the grinding duration. An increased ratio of grinding media versus the amount of ground material, while longer grinding duration increased the overall efficiency of the MCA process. The strength activity index (SAI) indicated an enhanced pozzolanic activity for the mechanochemically processed clay. Compressive strength tests have shown a strong correlation between an enhanced amorphization rate and increased compressive strength values.

  • 12.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Optimization of the Process Parameters Controlling the Degree of Amorphization during Mechanical Activation of Clay Using the Taguchi Method2019In: The 1st International Conference on Smart Materials for Sustainable Construction, MDPI, 2019, article id 15Conference paper (Refereed)
    Abstract [en]

    Mechanical activation in a planetary ball mill (BM) is an environmentally friendly process able to enhance the chemical and pozzolanic activity of natural clays. Those materials can be used as supplementary cementitious materials (SCMs) to partially replace Portland cement in concrete. The process parameters of the BM are directly related to the degree of amorphization and thus to the enhancement of the chemical activity. Design of experiments (DOE) is a well-known statistical tool, which can assist in selecting optimized conditions and in obtaining systematic data. However, full factorial design requires a large number of experiment. Taguchi method is based on the use of an Orthogonal Array (OA) to evaluate optimization of the selected factors but with less required experiments. In this study, three factors, each on 2 levels, were selected: ball to powder ratio (B/P) with level 3 and 25, time of grinding with level 5 and 20, and water to powder ratio (W/P) with level 0 and 1. The degree of amorphization (DOA) was selected as the main response for the Taguchi method. DOA was calculated as the ratio between the integral intensities of the main peak of the kaolinite [001] before and after grinding. For dry grinding, the predicted optimized value of DOA complied with the experimental results. Maximized DOA value was achieved for B/P equal to 25 and the grinding duration of 20. This method can be a valuable tool to predict the amorphization degree of minerals present in the natural clay, leading to the optimization of the mechanical activation process.

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  • 13.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Rajczakowska, Magdalena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Activation of a Raw Clay by Mechanochemical Process: Effects of Various Parameters on the Process Efficiency and Cementitious Properties2018In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, no 10, article id 1860Article in journal (Refereed)
    Abstract [en]

    The efficiency of the mechanochemical activation (MCA) is influenced by various process parameters as well as by the properties of the treated material. The main objective of this research was to optimize the MCA process, gaining enhancement of the chemical reactivity of a Swedish raw clay, which is going to be used as an alkali-activated cementitious binder. The effects of the amount of water, the filling ratio, the rotation speed, and the grinding duration on the amorphization degree were evaluated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Generally, wet and dry processes showed an extensive amorphization of both kaolinite and muscovite minerals present in the studied clay. On the contrary, quartz was amorphized mainly by the wet grinding process. The efficiency of both dry and wet grinding processes was enhanced by the increased number of grinding media versus the amount of the activated material. However, longer processing times caused significant agglomeration while a higher rotational speed enhanced the amorphization. Preliminary tests have shown that alkali activation of the processed clays produced hardened samples. Furthermore, the increased amorphization corresponded to the increased compressive strength values.

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  • 14.
    Tole, Ilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Rajczakowska, Magdalena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Humad, Abeer
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Kothari, Ankit
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Geopolymer Based on Mechanically Activated Air-cooled Blast Furnace Slag2020In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 5, article id 1134Article in journal (Refereed)
    Abstract [en]

    An efficient solution to increase the sustainability of building materials is to replace Portland cement with alkali-activated materials (AAM). Precursors for those systems are often based on water-cooled ground granulated blast furnace slags (GGBFS). Quenching of blast furnace slag can be done also by air but in that case, the final product is crystalline and with a very low reactivity. The present study aimed to evaluate the cementitious properties of a mechanically activated (MCA) air-cooled blast furnace slag (ACBFS) used as a precursor in sodium silicate alkali-activated systems. The unreactive ACBFS was processed in a planetary ball mill and its cementing performances were compared with an alkali-activated water-cooled GGBFS. Mixes based on mechanically activated ACBFS reached the 7-days compressive strength of 35 MPa and the 28-days compressive strength 45 MPa. The GGBFS-based samples showed generally higher compressive strength values.

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