PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS
An extremely porous geopolymer material - an incombustible alumino-silicate foam - can be prepared by incorporating gas-forming agents into mixtures consisting of an alkaline activating agent (NaOH + sodium water glass) and fly ash. Aluminium powder or materials containing elemental Si (silica fume,...
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| Format: | Article |
| Language: | English |
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University of Chemistry and Technology, Prague
2014-09-01
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| Series: | Ceramics-Silikáty |
| Subjects: | |
| Online Access: |
http://www.ceramics-silikaty.cz/2014/pdf/2014_03_188.pdf
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| author | Frantisek Skvara Rostislav Sulc Tisler Zdenek Skricik Petr Smilauer Vit Zlamalova Cilova Zuzana |
| author_facet | Frantisek Skvara Rostislav Sulc Tisler Zdenek Skricik Petr Smilauer Vit Zlamalova Cilova Zuzana |
| author_sort | Frantisek Skvara |
| collection | DOAJ |
| description | An extremely porous geopolymer material - an incombustible alumino-silicate foam - can be prepared by incorporating
gas-forming agents into mixtures consisting of an alkaline activating agent (NaOH + sodium water glass) and fly ash.
Aluminium powder or materials containing elemental Si (silica fume, FeSi or SiC) may be used as gas-forming agents.
Macroscopic pores are given rise thanks to the release of gaseous hydrogen generated during the reaction of aluminium,
respectively Si, in a strong alkaline environment. The formation of the foam becomes more intense if aluminium powder is
used instead of silica fume. The effect of silica fume can only be observed at concentrations ranging from 5 to 10 percent by
weight and at temperatures above 60oC because of a low content of elemental Si in silica fume. The foam formation takes
place immediately after the addition of aluminium powder to the mixture but the foam collapsing must be prevented by
incorporation of portland cement or lime. The Si reaction in the strong alkaline environment is boosted by the presence of
an alumino-silicate material, ie the fly ash. Geopolymer foams prepared by addition of gas-forming aluminium powder or
silica fume are characterized by similar pore sizes; the pore size is comparable with that observed in lime-silicate materials
produced in autoclave. The volume weight of geopolymer foams is similar to that of other inorganic foams. The strength of
geopolymer foams is dependent on their volume weigth. Mechanical properties of geopolymer foams were stable over the
investigated period of a year. Geopolymer foams are incombustible and can resist temperatures of up to 1000oC without any
sign of decomposition. Their shape does not change after exposure to temperatures ranging from 400 to 800oC. In contrast
to lime-silicate foams and cement-based foams the firing of geopolymer foams is not accompanied by the formation of any
cracks or by any additional changes (rehydration). |
| first_indexed | 2024-12-22T15:20:19Z |
| format | Article |
| id | doaj.art-5ce57fc0860442f1a1f11bfd2a996327 |
| institution | Directory Open Access Journal |
| issn | 0862-5468 1804-5847 |
| language | English |
| last_indexed | 2024-12-22T15:20:19Z |
| publishDate | 2014-09-01 |
| publisher | University of Chemistry and Technology, Prague |
| record_format | Article |
| series | Ceramics-Silikáty |
| spelling | doaj.art-5ce57fc0860442f1a1f11bfd2a9963272022-12-21T18:21:38ZengUniversity of Chemistry and Technology, PragueCeramics-Silikáty0862-54681804-58472014-09-01583188197.20160312094030PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMSFrantisek Skvara0Rostislav SulcTisler Zdenek1Skricik Petr2Smilauer VitZlamalova Cilova Zuzana3 Institute of Glass and Ceramics, Faculty of Chemical Technology, ICT Prague, Technicka 5, 16628 Prague 6, Czech Republic Institute of Glass and Ceramics, Faculty of Chemical Technology, ICT Prague, Technicka 5, 16628 Prague 6, Czech Republic Institute of Glass and Ceramics, Faculty of Chemical Technology, ICT Prague, Technicka 5, 16628 Prague 6, Czech Republic Institute of Glass and Ceramics, Faculty of Chemical Technology, ICT Prague, Technicka 5, 16628 Prague 6, Czech Republic An extremely porous geopolymer material - an incombustible alumino-silicate foam - can be prepared by incorporating gas-forming agents into mixtures consisting of an alkaline activating agent (NaOH + sodium water glass) and fly ash. Aluminium powder or materials containing elemental Si (silica fume, FeSi or SiC) may be used as gas-forming agents. Macroscopic pores are given rise thanks to the release of gaseous hydrogen generated during the reaction of aluminium, respectively Si, in a strong alkaline environment. The formation of the foam becomes more intense if aluminium powder is used instead of silica fume. The effect of silica fume can only be observed at concentrations ranging from 5 to 10 percent by weight and at temperatures above 60oC because of a low content of elemental Si in silica fume. The foam formation takes place immediately after the addition of aluminium powder to the mixture but the foam collapsing must be prevented by incorporation of portland cement or lime. The Si reaction in the strong alkaline environment is boosted by the presence of an alumino-silicate material, ie the fly ash. Geopolymer foams prepared by addition of gas-forming aluminium powder or silica fume are characterized by similar pore sizes; the pore size is comparable with that observed in lime-silicate materials produced in autoclave. The volume weight of geopolymer foams is similar to that of other inorganic foams. The strength of geopolymer foams is dependent on their volume weigth. Mechanical properties of geopolymer foams were stable over the investigated period of a year. Geopolymer foams are incombustible and can resist temperatures of up to 1000oC without any sign of decomposition. Their shape does not change after exposure to temperatures ranging from 400 to 800oC. In contrast to lime-silicate foams and cement-based foams the firing of geopolymer foams is not accompanied by the formation of any cracks or by any additional changes (rehydration). http://www.ceramics-silikaty.cz/2014/pdf/2014_03_188.pdf Geopolymer Foam Macro-porosity Fly ash |
| spellingShingle | Frantisek Skvara Rostislav Sulc Tisler Zdenek Skricik Petr Smilauer Vit Zlamalova Cilova Zuzana PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS Ceramics-Silikáty Geopolymer Foam Macro-porosity Fly ash |
| title | PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS |
| title_full | PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS |
| title_fullStr | PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS |
| title_full_unstemmed | PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS |
| title_short | PREPARATION AND PROPERTIES OF FLY ASH-BASED GEOPOLYMER FOAMS |
| title_sort | preparation and properties of fly ash based geopolymer foams |
| topic | Geopolymer Foam Macro-porosity Fly ash |
| url |
http://www.ceramics-silikaty.cz/2014/pdf/2014_03_188.pdf
|
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