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Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis

Vogt, Oliver ; Ballschmiede, Conrad ; Ukrainczyk, Neven ; Koenders, Eddie (2021):
Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis. (Publisher's Version)
In: Materials, 13 (20), MDPI, ISSN 1996-1944,
DOI: 10.26083/tuprints-00019250,
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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Evaluation of Sulfuric Acid-Induced Degradation of Potassium Silicate Activated Metakaolin Geopolymers by Semi-Quantitative SEM-EDX Analysis
Language: English
Abstract:

Geopolymers are synthesized by mixing powdery solids, rich in amorphous silicon and aluminum species, with an alkaline solution, which leads to the formation of an inorganic alumosilicate network. Their acid resistance is affected by the composition, the porosity, and pore size distribution of the hardened binder as well as the type and concentration of the acidic solution. In the present study, two geopolymer mixtures with varying liquid-to-solid ratios and Si/Al ratios were exposed to a sulfuric acid solution (pH = 1) and analyzed after different durations of exposure (7, 14, 28, 56, and 70 days) by using a light microscope and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). SEM-EDX elemental mapping was used to evaluate the degradation from depth profiles of silicon (Si), aluminum (Al), and potassium (K) leaching. The results clearly show the leaching kinetics of potassium and the dealumination of the network. The separate consideration of specific reaction steps in the course of degradation, namely the depth of erosion (DE), the depth of deterioration (DD), and the depth of reaction for certain elements (DR(e)), indicate a combination of chemical and diffusion controlled degradation mechanisms.

Journal or Publication Title: Materials
Journal volume: 13
Number: 20
Publisher: MDPI
Collation: 23 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
600 Technik, Medizin, angewandte Wissenschaften > 690 Hausbau, Bauhandwerk
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials
Date Deposited: 03 Aug 2021 07:25
Last Modified: 03 Aug 2021 07:25
DOI: 10.26083/tuprints-00019250
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-192500
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19250
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