Abstract
The article presents the latest results of the leaching of alkali from geopolymers depending on the introduced additions in the form of aluminum calcium cement and nanometric titanium oxide. Aluminum calcium cements were introduced in two variants: G40 (>40% Al2O3) and G70 (>70% Al2O3) in amounts of 0%, 2%, and 4% by weight. Titanium oxide was also incorporated in amounts of 2% and 4% by weight. The results of conductivity tests of solutions in which geopolymers were immersed were carried out. On this basis, it was found that geopolymers cured in the aquatic environment have a lower risk of efflorescence in the later periods of their use due to leaching of compounds at the stage of aquatic curing. In addition, it was found that the addition of calcium aluminum cements decreases the leaching of substances from geopolymers. It was also found that geopolymers based on an 8 M NaOH solution have greater leaching than when using a 10 M solution. The results of the compressive strength tests for the tested samples were also presented.
Highlights
Due to the EU (European Union) policy on reducing greenhouse gas emissions, the important driving force for the implementation of geopolymer concrete is the prospect of significantly reducingCO2 emissions in the production process compared to CO2 emissions in the production of Portland cement [1,2,3]
In the case of metakaolin, it is the high price of this raw material, while in the case of fly ash, it is the large variability of its oxide composition and morphology [5]
A very important barrier related to the use of geopolymer products is the occurrence of so-called efflorescence on geopolymer surfaces, regardless of whether they are based on metakaolin, fly ash, volcanic tuff, or other aluminosilicate precursors
Summary
Due to the EU (European Union) policy on reducing greenhouse gas emissions, the important driving force for the implementation of geopolymer concrete is the prospect of significantly reducingCO2 emissions in the production process compared to CO2 emissions in the production of Portland cement [1,2,3]. Due to the EU (European Union) policy on reducing greenhouse gas emissions, the important driving force for the implementation of geopolymer concrete is the prospect of significantly reducing. The key barriers associated with the widespread use of geopolymers are problems with the so-called precursors. A very important barrier related to the use of geopolymer products is the occurrence of so-called efflorescence on geopolymer surfaces, regardless of whether they are based on metakaolin, fly ash, volcanic tuff, or other aluminosilicate precursors. This is not just an aesthetic problem. Many scientific centers are working on limiting the formation of efflorescence and developing additives to prevent their formation [6,7,8]
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