Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites

A metakaolinite-based geopolymer binder was prepared by using calcined claystone as the main raw material and potassium as the alkaline activator. Chamotte was added (65 vol%) to form geopolymer composites. Potassium hydroxide (KOH) was used to adjust the molar ratio of K/Al and the effect of K/Al o...

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Autores principales:	Jan Kohout, Petr Koutník, Pavlína Hájková, Eliška Kohoutová, Aleš Soukup
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	K-geopolymer metakaolinite claystone thermal properties mechanical properties Organic chemistry QD241-441
Acceso en línea:	https://doaj.org/article/c08d45b69e5e40efbc71d92b24e339f6
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spelling	oai:doaj.org-article:c08d45b69e5e40efbc71d92b24e339f62021-11-11T18:46:22ZEffect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites10.3390/polym132137542073-4360https://doaj.org/article/c08d45b69e5e40efbc71d92b24e339f62021-10-01T00:00:00Zhttps://www.mdpi.com/2073-4360/13/21/3754https://doaj.org/toc/2073-4360A metakaolinite-based geopolymer binder was prepared by using calcined claystone as the main raw material and potassium as the alkaline activator. Chamotte was added (65 vol%) to form geopolymer composites. Potassium hydroxide (KOH) was used to adjust the molar ratio of K/Al and the effect of K/Al on thermo-mechanical properties of geopolymer composites was investigated. This study aimed to analyze the effect of K/Al ratio and exposure to high temperatures (up to 1200 °C) on the compressive and flexural strengths, phase composition, pore size distribution, and thermal dilatation. With an increasing K/Al ratio, the crystallization temperature of the new phases (leucite and kalsilite) decreased. Increasing content of K/Al led to a decline in the onset temperature of the major shrinkage. The average pore size slightly increased with increasing K/Al ratio at laboratory temperature. Mechanical properties of geopolymer composites showed degradation with the increase of the K/Al ratio. The exception was the local maximum at a K/Al ratio equal to one. The results showed that the compressive strength decreases with increasing temperature. For thermal applications above 600 °C, it is better to use samples with lower K/Al ratios (0.55 or 0.70).Jan KohoutPetr KoutníkPavlína HájkováEliška KohoutováAleš SoukupMDPI AGarticleK-geopolymermetakaoliniteclaystonethermal propertiesmechanical propertiesOrganic chemistryQD241-441ENPolymers, Vol 13, Iss 3754, p 3754 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	K-geopolymer metakaolinite claystone thermal properties mechanical properties Organic chemistry QD241-441
spellingShingle	K-geopolymer metakaolinite claystone thermal properties mechanical properties Organic chemistry QD241-441 Jan Kohout Petr Koutník Pavlína Hájková Eliška Kohoutová Aleš Soukup Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
description	A metakaolinite-based geopolymer binder was prepared by using calcined claystone as the main raw material and potassium as the alkaline activator. Chamotte was added (65 vol%) to form geopolymer composites. Potassium hydroxide (KOH) was used to adjust the molar ratio of K/Al and the effect of K/Al on thermo-mechanical properties of geopolymer composites was investigated. This study aimed to analyze the effect of K/Al ratio and exposure to high temperatures (up to 1200 °C) on the compressive and flexural strengths, phase composition, pore size distribution, and thermal dilatation. With an increasing K/Al ratio, the crystallization temperature of the new phases (leucite and kalsilite) decreased. Increasing content of K/Al led to a decline in the onset temperature of the major shrinkage. The average pore size slightly increased with increasing K/Al ratio at laboratory temperature. Mechanical properties of geopolymer composites showed degradation with the increase of the K/Al ratio. The exception was the local maximum at a K/Al ratio equal to one. The results showed that the compressive strength decreases with increasing temperature. For thermal applications above 600 °C, it is better to use samples with lower K/Al ratios (0.55 or 0.70).
format	article
author	Jan Kohout Petr Koutník Pavlína Hájková Eliška Kohoutová Aleš Soukup
author_facet	Jan Kohout Petr Koutník Pavlína Hájková Eliška Kohoutová Aleš Soukup
author_sort	Jan Kohout
title	Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
title_short	Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
title_full	Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
title_fullStr	Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
title_full_unstemmed	Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites
title_sort	effect of k/al molar ratio on the thermo-mechanical properties of metakaolinite-based geopolymer composites
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/c08d45b69e5e40efbc71d92b24e339f6
work_keys_str_mv	AT jankohout effectofkalmolarratioonthethermomechanicalpropertiesofmetakaolinitebasedgeopolymercomposites AT petrkoutnik effectofkalmolarratioonthethermomechanicalpropertiesofmetakaolinitebasedgeopolymercomposites AT pavlinahajkova effectofkalmolarratioonthethermomechanicalpropertiesofmetakaolinitebasedgeopolymercomposites AT eliskakohoutova effectofkalmolarratioonthethermomechanicalpropertiesofmetakaolinitebasedgeopolymercomposites AT alessoukup effectofkalmolarratioonthethermomechanicalpropertiesofmetakaolinitebasedgeopolymercomposites
_version_	1718431726026358784

Effect of K/Al Molar Ratio on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites

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