K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test
In this paper, four near-net shaped foams were produced via direct foaming, starting from a benchmark metakaolin-based geopolymer formulation. Hydrogen peroxide and metallic silicon were used in different amounts as blowing agents to change the porosity from meso- to ultra-macro-porosity. Foams were...
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MDPI AG
2022-01-01
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| Online Access: | https://www.mdpi.com/1996-1944/15/3/1008 |
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| author | Elettra Papa Elena Landi Francesco Miccio Valentina Medri |
| author_facet | Elettra Papa Elena Landi Francesco Miccio Valentina Medri |
| author_sort | Elettra Papa |
| collection | DOAJ |
| description | In this paper, four near-net shaped foams were produced via direct foaming, starting from a benchmark metakaolin-based geopolymer formulation. Hydrogen peroxide and metallic silicon were used in different amounts as blowing agents to change the porosity from meso- to ultra-macro-porosity. Foams were characterized by bulk densities ranging from 0.34 to 0.66 g cm<sup>−3</sup>, total porosity from 70% to 84%, accessible porosity from 41% to 52% and specific surface area from 47 to 94 m<sup>2</sup> g<sup>−1</sup>. Gas permeability tests were performed, showing a correlation between the pore features and the processing methods applied. The permeability coefficients k<sub>1</sub> (Darcian) and k<sub>2</sub> (non-Darcian), calculated applying Forchheimer’s equation, were higher by a few orders of magnitude for the foams made using H<sub>2</sub>O<sub>2</sub> than those made with metallic silicon, highlighting the differing flow resistance according to the interconnected porosity. The gas permeability data indicated that the different geopolymer foams, obtained via direct foaming, performed similarly to other porous materials such as granular beds, fibrous filters and gel-cast foams, indicating the possibility of their use in a broad spectrum of applications. |
| first_indexed | 2024-03-09T23:36:17Z |
| format | Article |
| id | doaj.art-a64ca317adc2466c9896786e71baefd7 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T23:36:17Z |
| publishDate | 2022-01-01 |
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| series | Materials |
| spelling | doaj.art-a64ca317adc2466c9896786e71baefd72023-11-23T17:00:45ZengMDPI AGMaterials1996-19442022-01-01153100810.3390/ma15031008K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability TestElettra Papa0Elena Landi1Francesco Miccio2Valentina Medri3National Research Council of Italy, Institute of Science and Technology for Ceramics (CNR-ISTEC), Via Granarolo 64, 48018 Faenza, ItalyNational Research Council of Italy, Institute of Science and Technology for Ceramics (CNR-ISTEC), Via Granarolo 64, 48018 Faenza, ItalyNational Research Council of Italy, Institute of Science and Technology for Ceramics (CNR-ISTEC), Via Granarolo 64, 48018 Faenza, ItalyNational Research Council of Italy, Institute of Science and Technology for Ceramics (CNR-ISTEC), Via Granarolo 64, 48018 Faenza, ItalyIn this paper, four near-net shaped foams were produced via direct foaming, starting from a benchmark metakaolin-based geopolymer formulation. Hydrogen peroxide and metallic silicon were used in different amounts as blowing agents to change the porosity from meso- to ultra-macro-porosity. Foams were characterized by bulk densities ranging from 0.34 to 0.66 g cm<sup>−3</sup>, total porosity from 70% to 84%, accessible porosity from 41% to 52% and specific surface area from 47 to 94 m<sup>2</sup> g<sup>−1</sup>. Gas permeability tests were performed, showing a correlation between the pore features and the processing methods applied. The permeability coefficients k<sub>1</sub> (Darcian) and k<sub>2</sub> (non-Darcian), calculated applying Forchheimer’s equation, were higher by a few orders of magnitude for the foams made using H<sub>2</sub>O<sub>2</sub> than those made with metallic silicon, highlighting the differing flow resistance according to the interconnected porosity. The gas permeability data indicated that the different geopolymer foams, obtained via direct foaming, performed similarly to other porous materials such as granular beds, fibrous filters and gel-cast foams, indicating the possibility of their use in a broad spectrum of applications.https://www.mdpi.com/1996-1944/15/3/1008geopolymer foamdirect foamingporositypermeability |
| spellingShingle | Elettra Papa Elena Landi Francesco Miccio Valentina Medri K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test Materials geopolymer foam direct foaming porosity permeability |
| title | K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test |
| title_full | K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test |
| title_fullStr | K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test |
| title_full_unstemmed | K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test |
| title_short | K<sub>2</sub>O-Metakaolin-Based Geopolymer Foams: Production, Porosity Characterization and Permeability Test |
| title_sort | k sub 2 sub o metakaolin based geopolymer foams production porosity characterization and permeability test |
| topic | geopolymer foam direct foaming porosity permeability |
| url | https://www.mdpi.com/1996-1944/15/3/1008 |
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