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Solubility of precursors and carbonation of waterglass-free geopolymers

Werling, N.; Dehn, F.; Krause, F.; Steudel, A.; Schuhmann, R.; Emmerich, K.

Abstract:
Geopolymers have the potential to function as an environmentally friendly substitute for ordinary Portland cement, with up to 80% less CO$_{2}$ emission during production. The effect is best utilized for geopolymers prepared with amorphous silica instead of waterglass (Na$_{2x}$Si$_{y}$O$_{2y+x}$) to adjust the Si:Al ratio. The reactivity of the precursors with the alkaline activator affects the final mineralogical properties of the binder. The purpose of the present study was to investigate the amount of different phases formed during geopolymerization and to understand the quantitative evolution of carbonation during geopolymer synthesis by determining the solubility of metakaolinite and amorphous SiO$_{2}$ in NaOH at various concentrations. The solubility was studied by ICP-OES measurements. X-ray diffraction was used for qualitative and quantitative phase analysis of the geopolymers. The solubility of the precursors increased with calcination temperature of metakaolinite, reaction time for amorphous SiO$_{2}$, and at higher NaOH concentrations. Partial dissolution resulted in free Na$^{+}$, which is a source for the formation of carbonates in the geopolymers. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000126649
Veröffentlicht am 25.11.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Funktionelle Grenzflächen (IFG)
Institut für Massivbau und Baustofftechnologie (IMB)
Kompetenzzentrum für Materialfeuchte (CMM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 0009-8604, 1552-8367
KITopen-ID: 1000126649
Erschienen in Clays and clay minerals
Nachgewiesen in Web of Science
Scopus
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