Ukrainczyk, Neven (2022)
Simple Model for Alkali Leaching from Geopolymers: Effects of Raw Materials and Acetic Acid Concentration on Apparent Diffusion Coefficient.
In: Materials, 14 (6)
doi: 10.3390/ma14061425
Article, Bibliographie
This is the latest version of this item.
Abstract
This paper investigates alkali leaching from geopolymers under various concentrations of acetic acid solutions. The effects of the raw metakaolin purity as well as fly ash-based geopolymer mortars and pastes are considered. A new methodology for (acetic) acid attack is proposed, adapting standard approaches, where the concentration of the leached alkali in the exposure solution is measured over time. The applicability of a simple diffusion-based mathematical model to determine the apparent diffusion coefficient (Dapp) for geopolymer pastes and mortars was validated. At the end of the paste tests, microstructural alterations of the specimens’ cross-sections were analyzed microscopically, revealing occurrence of degradation across the outermost surface parts and, especially under acid attack, the formation of long cracks that connect the surface with the intact inner zone. Drastically different Dapp are discussed in terms of the differences in the mix designs, principally resulting in different alkali-binding capacities of the geopolymers, while the acid promoted dissolution and increased porosity. As a result of this interpretation, it was concluded that Dapp is governed mainly by the chemistry of the alkali release from the gel, as it overruled the effects of porosity and cracks.
| Item Type: | Article |
|---|---|
| Erschienen: | 2022 |
| Creators: | Ukrainczyk, Neven |
| Type of entry: | Bibliographie |
| Title: | Simple Model for Alkali Leaching from Geopolymers: Effects of Raw Materials and Acetic Acid Concentration on Apparent Diffusion Coefficient |
| Language: | English |
| Date: | 2022 |
| Publisher: | MDPI |
| Journal or Publication Title: | Materials |
| Volume of the journal: | 14 |
| Issue Number: | 6 |
| Collation: | 20 Seiten |
| DOI: | 10.3390/ma14061425 |
| Corresponding Links: | |
| Abstract: | This paper investigates alkali leaching from geopolymers under various concentrations of acetic acid solutions. The effects of the raw metakaolin purity as well as fly ash-based geopolymer mortars and pastes are considered. A new methodology for (acetic) acid attack is proposed, adapting standard approaches, where the concentration of the leached alkali in the exposure solution is measured over time. The applicability of a simple diffusion-based mathematical model to determine the apparent diffusion coefficient (Dapp) for geopolymer pastes and mortars was validated. At the end of the paste tests, microstructural alterations of the specimens’ cross-sections were analyzed microscopically, revealing occurrence of degradation across the outermost surface parts and, especially under acid attack, the formation of long cracks that connect the surface with the intact inner zone. Drastically different Dapp are discussed in terms of the differences in the mix designs, principally resulting in different alkali-binding capacities of the geopolymers, while the acid promoted dissolution and increased porosity. As a result of this interpretation, it was concluded that Dapp is governed mainly by the chemistry of the alkali release from the gel, as it overruled the effects of porosity and cracks. |
| Uncontrolled Keywords: | geopolymers, metakaolin purity, alkali leaching, acetic acid attack, mathematical modeling, apparent diffusion coefficient |
| Classification DDC: | 600 Technology, medicine, applied sciences > 600 Technology 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering |
| Divisions: | 13 Department of Civil and Environmental Engineering Sciences 13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials |
| Date Deposited: | 02 Aug 2024 12:37 |
| Last Modified: | 02 Aug 2024 12:37 |
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| Suche nach Titel in: | TUfind oder in Google |
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Simple Model for Alkali Leaching from Geopolymers: Effects of Raw Materials and Acetic Acid Concentration on Apparent Diffusion Coefficient. (deposited 02 Feb 2022 13:29)
- Simple Model for Alkali Leaching from Geopolymers: Effects of Raw Materials and Acetic Acid Concentration on Apparent Diffusion Coefficient. (deposited 02 Aug 2024 12:37) [Currently Displayed]
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