Characteristics of Raw Materials Used for Alkaline Activation and Geopolymerization Processes

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Mineralogical Crystallography and Biomineralization".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 5449

Special Issue Editors

Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144, USA
Interests: crystal structure of clay minerals; interactions of crystals with environmental contaminants; environmental remediations using nano materials and Earth materials
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Guest Editor
Faculty of Materials Engineering and Physics, Cracow University of Technology, Al. Jana Pawła II 37, 31-864 Kraków, Poland
Interests: geopolymer; composite; lightweight material; fly-ash; additive manufacturing; fibre
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Guest Editor
Cracow University of Technology, Institute of Materials Engineering, Faculty of Material Engineering and Physics, Kraków, Poland
Interests: alkaline-activated materials
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Special Issue Information

Dear Colleagues,

Reducing the release of CO2 in the production and emission of CO2 is a highly important environmental problem in the production of concrete; there is a need to develop materials that can replace concrete with engineering materials whose production does not have such a heavy burden on the environment. The most promising alternative solutions for the production of Portland cement are technologies of materials production based on alkali activation and geopolymerization. Such materials have a significantly lower carbon footprint than traditional construction materials.

In addition, the above process has another environmental benefit, i.e. the possibility of using anthropogenic raw materials (minerals) such as slags and fly ashes and other wastes for the production. Modern energy, mining, and metallurgical industries produce huge amounts of post-processing waste, whose deposition may cause serious ecological problems related to soil and water contamination. Alkali activation enables one to use such waste as a raw material for manufacturing new products in low energy and low emission processes.

This Special Issue aims to attract original contributions in topics related to the usage of different raw materials for processes of alkali activation and geopolymerization, covering aspects ranging from the preparation of such materials (especially using natural or waste materials), their characterization, and application in different areas, especially in the construction industry.

We believe that this collection will summarize the current state-of-the-art in the field of characterization of raw materials used for alkaline activation and geopolymerization processes, and will become a source of new ideas resulting in the development of knowledge in this area.

Dr. Zhaohui Li
Dr. Kinga Korniejenko
Dr. Michał Łach
Guest Editors

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Keywords

  • alkaline activation
  • geopolymerization
  • fly ash
  • slag
  • mine tailings
  • industrial waste
  • clay
  • metakaolin
  • calcination
  • aggregate recycling

Published Papers (2 papers)

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Research

8 pages, 2975 KiB  
Article
Long-Term Properties of Different Fiber Reinforcement Effect on Fly Ash-Based Geopolymer Composite
by Rihards Gailitis, Andina Sprince, Tomass Kozlovskis, Liga Radina, Leonids Pakrastins and Nikolai Vatin
Crystals 2021, 11(7), 760; https://doi.org/10.3390/cryst11070760 - 29 Jun 2021
Cited by 14 | Viewed by 2619
Abstract
Geopolymer composites have been around only for 40 years. Nowadays, they are used in buildings and infrastructures of various kinds. A geopolymer’s main benefit is that it is a green material that is partially made by utilizing waste products. The carbon footprint from [...] Read more.
Geopolymer composites have been around only for 40 years. Nowadays, they are used in buildings and infrastructures of various kinds. A geopolymer’s main benefit is that it is a green material that is partially made by utilizing waste products. The carbon footprint from geopolymer matrix manufacturing is at least two times less than Portland cement manufacturing. Due to the nature of the geopolymer manufacturing process, there is a high risk of shrinkage that could develop unwanted micro-cracks that could reduce strength and create higher creep strains. Because of this concern, a common strategy to reduce long-term strains of the material, such as shrinkage and creep, is to add fiber reinforcement that would constrain crack development in the material. This article aims to determine how various kinds and amounts of different fiber reinforcement affect fly ash-based geopolymer composites’ creep strains in compression. Specimen mixes were produced with 1% steel fibers, 1% polypropylene fibers, 5% polypropylene fibers, and without fibers (plain geopolymer). For creep and shrinkage testing, cylindrical specimens Ø46 × 190 mm were used. The highest creep resistance was observed in 5% polypropylene fiber specimens, followed by 1% polypropylene fiber, plain, and 1% steel fiber specimens. The highest compressive strength was observed in 1% polypropylene fiber specimens, followed by plain specimens, 1% steel fiber specimens, and 5% polypropylene fiber-reinforced specimens. The only fiber-reinforced geopolymer mix with improved long-term properties was observed with 1% polypropylene fiber inclusion, whereas other fiber-introduced mixes showed significant decreases in long-term properties. The geopolymer composite mix with 1% polypropylene fiber reinforcement showed a reduction in creep strains of 31% compared to the plain geopolymer composite. Full article
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13 pages, 3475 KiB  
Article
Interactions between Cationic Dye Toluidine Blue and Fibrous Clay Minerals
by Qingfeng Wu, Kristen Carlson, Qi Cheng, Xisen Wang and Zhaohui Li
Crystals 2021, 11(6), 708; https://doi.org/10.3390/cryst11060708 - 20 Jun 2021
Cited by 6 | Viewed by 2146
Abstract
Interactions between cationic dyes and negatively charged mineral surfaces have long attracted great attention from clay mineralogists, environmental scientists, and chemical engineers. In this study, the interactions between a cationic dye toluidine blue (TB) and palygorskite and sepiolite were investigated under different experimental [...] Read more.
Interactions between cationic dyes and negatively charged mineral surfaces have long attracted great attention from clay mineralogists, environmental scientists, and chemical engineers. In this study, the interactions between a cationic dye toluidine blue (TB) and palygorskite and sepiolite were investigated under different experimental conditions. The results showed that in addition to cation exchange, the specific surface area (SSA) of the minerals, particularly the formation of dimer molecules on the surface of both minerals, also accounted for the much higher TB uptake in comparison to their cation exchange capacities (CEC). The TB molecules were sorbed to the external surfaces, as no d-spacing expansion was observed in X-ray diffraction analyses. FTIR analyses showed strong interactions between the C=N or N-(CH3)2 group and the mineral surfaces, suggesting net electrostatic interactions if either of these functional groups bears a positive charge. Results from molecular dynamic simulations suggested dense monolayer TB formation on palygorskite because of its limited SSA and large CEC values. In comparison, a loosely dimeric formation was revealed on sepiolite for its large SSA and limited CEC values. Therefore, palygorskite is a better carrier for the sorption of cationic dyes, as evidenced by Maya blue paintings. Full article
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