| Title: | Enhancing densification of metakaolin-based geopolymers via the cold sintering process |
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| Authors: | ID Jabr, Abdullah (Author)
ID Škapin, Srečo D. (Author)
ID Tominc, Sara (Author)
ID Daneu, Nina (Author)
ID Koenig, Jakob (Author)
ID Ducman, Vilma (Author)
ID Korat Bensa, Lidija (Author)
ID Bermejo, Raúl (Author)
ID Spreitzer, Matjaž (Author) |
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| Files: |  URL - Source URL, visit https://doi.org/10.1016/j.oceram.2025.100863
 PDF - Presentation file, download (7,70 MB)
MD5: 7F0A08C8CF3A34928E460F10DE21264D
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| Language: | English |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: |  ZAG - Slovenian National Building and Civil Engineering Institute
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| Abstract: | Clay-based materials typically require high-temperature processing (>900 ◦C), resulting in high energy consumption. This study explores cold sintering of metakaolin (MK) powders to achieve high mechanical strength at significantly lower processing temperatures. By applying uniaxial pressure of 400 MPa and heating to only 240 ◦ C in the presence of 15 mol/L NaOH solution, successful densification of structurally sound and dense samples with an average density of 2.16 g/cm³ and a biaxial flexural strength of ~35 MPa was achieved. This strength surpasses that of conventionally sintered MK (1470 ◦C) by ~30 %. Densification was found to be governed by synergistic mechanisms involving MK exfoliation, conformal sintering around aggregates, and the precipitation of an amorphous sodium aluminosilicate hydrate phase. Crack formation was avoided through process optimization and verified using X-ray micro-computed tomography. These findings offer new insights into the chemo- mechanical mechanisms of cold sintering and demonstrate its potential as an efficient route for producing structural materials. |
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| Keywords: | cold sintering, metakaolin, geopolymer, delaminations, exfoliation |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Publication date: | 09.10.2025 |
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| Publisher: | Elsevier Ltd |
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| Year of publishing: | 2025 |
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| Number of pages: | str. 1-10 |
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| Numbering: | Vol. 24, [article no.] 100863 |
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| PID: | 20.500.12556/DiRROS-23872  |
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| UDC: | 621.7 |
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| ISSN on article: | 2666-5395 |
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| DOI: | 10.1016/j.oceram.2025.100863 |
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| COBISS.SI-ID: | 253167107 |
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| Copyright: | © 2025 The Authors |
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| Publication date in DiRROS: | 15.10.2025 |
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| Views: | 182 |
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| Downloads: | 83 |
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