Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3

The study of alkaline activated materials is very promising regarding the production of materials with high durability. The particle size and the content of reactive silica e alumina (amorphous) influence the performance of the geopolymer as well as the type of activator. In this study, geopolymers...

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Autores principales:	Dayana Keitty Carmo Gonçalves, Sebastiana Luiza Bragança Lana, Rosemary Bom Conselho Sales, Maria Teresa Paulino Aguilar
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2022
Materias:	Geopolymerization Amorphicity Particle size, mechanical strength, water absorption Materials of engineering and construction. Mechanics of materials TA401-492
Acceso en línea:	https://doaj.org/article/d275549055334c69bce7f2c24ad0f750
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spelling	oai:doaj.org-article:d275549055334c69bce7f2c24ad0f7502021-11-22T04:25:41ZStudy of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO32214-509510.1016/j.cscm.2021.e00778https://doaj.org/article/d275549055334c69bce7f2c24ad0f7502022-06-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S221450952100293Xhttps://doaj.org/toc/2214-5095The study of alkaline activated materials is very promising regarding the production of materials with high durability. The particle size and the content of reactive silica e alumina (amorphous) influence the performance of the geopolymer as well as the type of activator. In this study, geopolymers are produced using metakaolin precursors with similar chemical composition and different amorphities and particle sizes. KOH and K2SiO3 are used as activators, therefore, potassium solutions provide a lower viscosity of the pastes, better workability with a lower liquid to solids ratio and, consequently, better mechanical strength, denser and exhibited low porosity than sodium solutions. Produced precursors and pastes were characterized in the solid state by fluorescence X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance single pulse and nuclear magnetic resonance cross-polarization. The pastes were also evaluated for compressive strength, bulk density and water absorption. The results indicate that geopolymers can be obtained from metakaolins of incomplete calcination and with average grain diameter of 23.5 µm and 12.0 µm. Despite having similar bulk density and a slight difference in water absorption, the mechanical strength of the paste produced with coarser and more amorphous metakaolin at 28 days is 50 MPa, while the other paste reaches 22 MPa. The difference in mechanical strength is likely due to the greater extent of geopolymerization indicated by the NMR. The difference in the precursors and consequently in the pastes impacts on the expected durability.Dayana Keitty Carmo GonçalvesSebastiana Luiza Bragança LanaRosemary Bom Conselho SalesMaria Teresa Paulino AguilarElsevierarticleGeopolymerizationAmorphicityParticle size, mechanical strength, water absorptionMaterials of engineering and construction. Mechanics of materialsTA401-492ENCase Studies in Construction Materials, Vol 16, Iss , Pp e00778- (2022)
institution	DOAJ
collection	DOAJ
language	EN
topic	Geopolymerization Amorphicity Particle size, mechanical strength, water absorption Materials of engineering and construction. Mechanics of materials TA401-492
spellingShingle	Geopolymerization Amorphicity Particle size, mechanical strength, water absorption Materials of engineering and construction. Mechanics of materials TA401-492 Dayana Keitty Carmo Gonçalves Sebastiana Luiza Bragança Lana Rosemary Bom Conselho Sales Maria Teresa Paulino Aguilar Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
description	The study of alkaline activated materials is very promising regarding the production of materials with high durability. The particle size and the content of reactive silica e alumina (amorphous) influence the performance of the geopolymer as well as the type of activator. In this study, geopolymers are produced using metakaolin precursors with similar chemical composition and different amorphities and particle sizes. KOH and K2SiO3 are used as activators, therefore, potassium solutions provide a lower viscosity of the pastes, better workability with a lower liquid to solids ratio and, consequently, better mechanical strength, denser and exhibited low porosity than sodium solutions. Produced precursors and pastes were characterized in the solid state by fluorescence X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance single pulse and nuclear magnetic resonance cross-polarization. The pastes were also evaluated for compressive strength, bulk density and water absorption. The results indicate that geopolymers can be obtained from metakaolins of incomplete calcination and with average grain diameter of 23.5 µm and 12.0 µm. Despite having similar bulk density and a slight difference in water absorption, the mechanical strength of the paste produced with coarser and more amorphous metakaolin at 28 days is 50 MPa, while the other paste reaches 22 MPa. The difference in mechanical strength is likely due to the greater extent of geopolymerization indicated by the NMR. The difference in the precursors and consequently in the pastes impacts on the expected durability.
format	article
author	Dayana Keitty Carmo Gonçalves Sebastiana Luiza Bragança Lana Rosemary Bom Conselho Sales Maria Teresa Paulino Aguilar
author_facet	Dayana Keitty Carmo Gonçalves Sebastiana Luiza Bragança Lana Rosemary Bom Conselho Sales Maria Teresa Paulino Aguilar
author_sort	Dayana Keitty Carmo Gonçalves
title	Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
title_short	Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
title_full	Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
title_fullStr	Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
title_full_unstemmed	Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3
title_sort	study of metakaolins with different amorphities and particle sizes activated by koh and k2sio3
publisher	Elsevier
publishDate	2022
url	https://doaj.org/article/d275549055334c69bce7f2c24ad0f750
work_keys_str_mv	AT dayanakeittycarmogoncalves studyofmetakaolinswithdifferentamorphitiesandparticlesizesactivatedbykohandk2sio3 AT sebastianaluizabragancalana studyofmetakaolinswithdifferentamorphitiesandparticlesizesactivatedbykohandk2sio3 AT rosemarybomconselhosales studyofmetakaolinswithdifferentamorphitiesandparticlesizesactivatedbykohandk2sio3 AT mariateresapaulinoaguilar studyofmetakaolinswithdifferentamorphitiesandparticlesizesactivatedbykohandk2sio3
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Study of metakaolins with different amorphities and particle sizes activated by KOH and K2SiO3

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