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  1. Article ; Online: Thermodynamics of the Eu(III)-Mg-SO

    Dos Santos, P F / Lassin, A / Gaona, X / Garbev, K / Altmaier, M / Madé, B

    Dalton transactions (Cambridge, England : 2003)

    2024  Volume 53, Issue 14, Page(s) 6289–6299

    Abstract: The solubility of Eu(III) was investigated under undersaturated conditions in acidic, dilute to concentrated ... ...

    Abstract The solubility of Eu(III) was investigated under undersaturated conditions in acidic, dilute to concentrated MgSO
    Language English
    Publishing date 2024-04-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472887-4
    ISSN 1477-9234 ; 1364-5447 ; 0300-9246 ; 1477-9226
    ISSN (online) 1477-9234 ; 1364-5447
    ISSN 0300-9246 ; 1477-9226
    DOI 10.1039/d3dt04322c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Book ; Online: Chemo-mechanical characterization of hydrated Calcium-Hydrosilicates with coupled Raman and nanoindentation measurements

    Stemmermann, P. / Garbev, K. / Gasharova, B. / Beuchle, G. / Haist, M. / Divoux, T.

    2020  

    Abstract: Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS) that possesses a potential for minimizing the ratio C/S from above 3 in OPC down to 1, which significantly reduces the amount of CO$_2$ released during processing. ...

    Abstract Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS) that possesses a potential for minimizing the ratio C/S from above 3 in OPC down to 1, which significantly reduces the amount of CO$_2$ released during processing. The reaction kinetics of hCHS differs from that of classical clinker phases due to the presence of highly reactive silicate species, which involve silanol groups instead of pure calcium silicates and aluminates and aluminoferrites. In contrast to Portland cement, no calcium hydroxide is formed during hydration, which otherwise regulates the Ca concentration. Without the buffering role of Ca(OH)$_2$ the concentration of the dissolved species c(Ca$^{2+}$) and c(SiO$_4^{4-}$) and the corresponding pH must be controlled to ensure a reproducible reaction. Pure hCHS reacts isochemically with water, resulting in a C-S-H phase with the same chemical composition as a single hydration product, with a homogeneous distribution of the main elements Ca and Si throughout the sample. Here we study via nanoindentation the mechanical properties of two different types of hardened pastes made out of Celitement (C/S=1.28), with varying amounts of hCHS and variable water to cement ratio. We couple nanoindentation grids with Raman mappings to link the nanoscale mechanical properties to individual microstructural components, yielding in-depth insight into the mechanics of the mineralogical phases constituting the hardened cement paste. We show that we can identify in hardened Celitement paste both fresh C-S-H with varying density, and C-S-H from the raw material using their specific Raman spectra, while simultaneously measuring their mechanical properties. Albeit not suitable for phase identification, EDX measurements provide valuable information about the distribution of alkalis, thus further helping to understand the reaction pattern of hCHS.

    Comment: 32 pages, 8 figures
    Keywords Condensed Matter - Materials Science ; Condensed Matter - Mesoscale and Nanoscale Physics ; Physics - Applied Physics
    Subject code 660
    Publishing date 2020-03-10
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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  3. Article: Chemo-mechanical characterization of hydrated calcium-hydrosilicates with coupled Raman- and nanoindentation measurements

    Stemmermann, P / Garbev, K / Gasharova, B / Beuchle, G / Haist, M / Divoux, T

    Applied geochemistry. 2020 July, v. 118

    2020  

    Abstract: Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS). It is produced by mechanochemical activation of Calcium-Silicate-Hydrates (C-S-H) in a grinding process. Due to the lack of typical clinker minerals, its CaO/SiO₂ ...

    Abstract Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS). It is produced by mechanochemical activation of Calcium-Silicate-Hydrates (C-S-H) in a grinding process. Due to the lack of typical clinker minerals, its CaO/SiO₂ (C/S) ratio can be minimized from above 3 (as in Ordinary Portland Cement) down to 1, which significantly reduces the amount of CO₂ released during processing. The reaction kinetics of hCHS differs from that of classical clinker phases due to the presence of highly reactive silicate species, which involve silanol groups instead of pure calcium silicates and aluminates and aluminoferrites. In contrast to Portland cement, no calcium hydroxide is formed during hydration, which otherwise regulates the Ca concentration. Without the buffering role of Ca(OH)₂ the concentration of the dissolved species c(Ca²⁺) and c(SiO₄⁴⁻) and the corresponding pH must be controlled to ensure a reproducible reaction. Pure hCHS reacts isochemically with water, resulting in a C-S-H phase with the same chemical composition as a single hydration product, with a homogeneous distribution of the main elements Ca and Si throughout the sample. Here we study via nanoindentation tests, the mechanical properties of two different types of hardened pastes made out of Celitement (C/S = 1.28), with varying amounts of hCHS and variable water to cement ratio. We couple nanoindentation grids with Raman mappings to link the nanoscale mechanical properties to individual microstructural components, yielding in-depth insight into the mechanics of the mineralogical phases constituting the hardened cement paste. We show that we can identify in hardened Celitement paste both fresh C-S-H with varying density, and C-S-H from the raw material using their specific Raman spectra, while simultaneously measuring their mechanical properties. Albeit not suitable for phase identification, supplemental EDX measurements provide valuable information about the distribution of alkalis, thus further helping to understand the reaction pattern of hCHS.
    Keywords Raman spectroscopy ; alkalis ; calcium ; calcium hydroxide ; calcium oxide ; carbon dioxide ; cement ; chemical composition ; energy-dispersive X-ray analysis ; geochemistry ; grinding ; mechanical properties ; mechanochemistry ; minerals ; pH ; pastes ; raw materials ; reaction kinetics ; silica ; silicates ; silicon
    Language English
    Dates of publication 2020-07
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 1499242-5
    ISSN 0883-2927
    ISSN 0883-2927
    DOI 10.1016/j.apgeochem.2020.104582
    Database NAL-Catalogue (AGRICOLA)

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  4. Book ; Audio / Video ; Thesis: Struktur, Eigenschaften und quantitative Rietveldanalyse von hydrothermal kristallisierten Calciumsilikathydraten (C-S-H-Phasen)

    Garbev, Krassimir

    (Wissenschaftliche Berichte / Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, FZKA ; 6877)

    2004  

    Author's details Krassimir Garbev
    Series title Wissenschaftliche Berichte / Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, FZKA ; 6877
    Language German ; English
    Size VI, XVIII, 241 S., Ill., graph. Darst., 30 cm
    Edition Als Ms. gedr.
    Publisher Forschungszentrum
    Publishing place Karlsruhe
    Document type Book ; Audio / Video ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Heidelberg, 2003
    Note Mit engl. Zsfassung
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  5. Article ; Online: Starve to Sustain-An Ancient Syrian Landrace of Sorghum as Tool for Phosphorous Bio-Economy?

    Kanbar, Adnan / Mirzai, Madeleine / Abuslima, Eman / Flubacher, Noemi / Eghbalian, Rose / Garbev, Krassimir / Bergfeldt, Britta / Ullrich, Angela / Leibold, Hans / Eiche, Elisabeth / Müller, Mario / Mokry, Markus / Stapf, Dieter / Nick, Peter

    International journal of molecular sciences

    2021  Volume 22, Issue 17

    Abstract: Phosphorus (P) is an essential macronutrient, playing a role in developmental and metabolic processes in plants. To understand the local and systemic responses of sorghum to inorganic phosphorus ( ... ...

    Abstract Phosphorus (P) is an essential macronutrient, playing a role in developmental and metabolic processes in plants. To understand the local and systemic responses of sorghum to inorganic phosphorus (P
    MeSH term(s) Gene Expression Regulation, Plant ; Oryza/growth & development ; Oryza/metabolism ; Phosphate Transport Proteins/metabolism ; Phosphorus/metabolism ; Plant Development ; Plant Proteins/metabolism ; Plant Roots/growth & development ; Plant Roots/metabolism ; Plant Shoots/growth & development ; Plant Shoots/metabolism ; Sorghum/chemistry ; Sorghum/metabolism ; Stress, Physiological
    Chemical Substances Phosphate Transport Proteins ; Plant Proteins ; Phosphorus (27YLU75U4W)
    Language English
    Publishing date 2021-08-27
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms22179312
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Indirect observation of structured incipient zeolite nanoparticles in clear precursor solutions.

    Tosheva, Lubomira / Mihailova, Boriana / Wee, Lik H / Gasharova, Biliana / Garbev, Krassimir / Doyle, Aidan M

    Angewandte Chemie (International ed. in English)

    2008  Volume 47, Issue 45, Page(s) 8650–8653

    MeSH term(s) Colloids/chemical synthesis ; Colloids/chemistry ; Gold/chemistry ; Membranes, Artificial ; Nanoparticles/chemistry ; Particle Size ; Silanes/chemistry ; Silicates/chemical synthesis ; Silicates/chemistry ; Solutions/chemistry ; Spectrophotometry, Infrared ; Surface Properties ; Zeolites/chemistry
    Chemical Substances Colloids ; Membranes, Artificial ; Silanes ; Silicates ; Solutions ; Zeolites (1318-02-1) ; tetraethoxysilane (42064KRE49) ; Gold (7440-57-5)
    Language English
    Publishing date 2008
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.200802941
    Database MEDical Literature Analysis and Retrieval System OnLINE

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