SOLUBILITY OF PRECURSORS AND CARBONATION OF WATERGLASS-FREE GEOPOLYMERS

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 2 x Si y O 2 y + x ) to adjust...

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Bibliographic Details
Published in:Clays and clay minerals 2020-10, Vol.68 (5), p.524-531
Main Authors: Werling, N., Dehn, F., Krause, F., Steudel, A., Schuhmann, R., Emmerich, K.
Format: Article
Language:English
Subjects:
Biogeosciences
Carbon dioxide
Carbon dioxide emissions
Carbonates
Carbonation
Earth and Environmental Science
Earth Sciences
Geochemistry
Geopolymers
Medicinal Chemistry
Mineralogy
Nanoscale Science and Technology
Original Paper
Portland cement
Portland cements
Precursors
Qualitative analysis
Silica
Silicon dioxide
Sodium hydroxide
Soil Science & Conservation
Solubility
X-ray diffraction
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Summary: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 2 x Si y O 2 y + 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. Thermonatrite occurred prior to trona formation in all samples.
ISSN:0009-8604
1552-8367
DOI:10.1007/s42860-020-00096-4