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Article: Effects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature

TitleEffects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature
Authors
KeywordsGeopolymer mortar
High temperature
Metakaolin
Microstructure
X-ray computed microtomography
Issue Date2020
PublisherAmerican Society of Civil Engineers. The Journal's web site is located at http://www.pubs.asce.org/journals/mt.html
Citation
Journal of Materials in Civil Engineering, 2020, v. 32, p. article no. 04020369 How to Cite?
AbstractIn this study, we investigated the degradation process of metakaolin-based geopolymers exposed to high temperatures up to 1,000°C. The changes in mechanical properties, microstructure, and phase assemblage of the samples were studied, and the results demonstrated that at high temperatures the activator type [i.e., Na2SiO3/NaOH (Na/Na) and Na2SiO3/KOH (Na/K) solution] affected the degradation mechanisms of geopolymer mortars. (Na,K)-based geopolymer specimens demonstrated better thermal resistance at temperatures above 200°C. This was evident from the higher compressive strength, lower porosity, and less cracking tendency of this mixture. Compared to (Na,K)-based geopolymers, more mass loss may result in considerable drying shrinkage of (Na,Na)-based counterparts, which would further lead to the occurrence and development of cracks at ∼200°C. Above 200°C, the degradation of the mechanical properties of geopolymers could be attributed to crack development and degradation of material properties. Furthermore, compared to their (Na-Na)-based counterparts, (Na-K)-based geopolymers achieved improved chemical stability and did not form new crystalline phases above 1,000°C. Moreover, higher temperature exposure (1,000°C) led to significant sintering of geopolymers, forming a dense and homogeneous matrix and, as a result, improved mechanical properties of specimens. Overall, it showed that when specimens were exposed to different high temperatures, the mutual promoted effects between Na+ and K+ in geopolymers played a significant role in crack development, sintering, and new crystallization formation in the specimens.
Persistent Identifierhttp://hdl.handle.net/10722/293271
ISSN
2019 Impact Factor: 2.169
2015 SCImago Journal Rankings: 0.965
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorZhang, Y-
dc.contributor.authorYan, D-
dc.contributor.authorHan, N-
dc.contributor.authorAo, Y-
dc.contributor.authorChen, S-
dc.contributor.authorYe, H-
dc.contributor.authorFazli, H-
dc.contributor.authorYe, TN-
dc.date.accessioned2020-11-23T08:14:19Z-
dc.date.available2020-11-23T08:14:19Z-
dc.date.issued2020-
dc.identifier.citationJournal of Materials in Civil Engineering, 2020, v. 32, p. article no. 04020369-
dc.identifier.issn0899-1561-
dc.identifier.urihttp://hdl.handle.net/10722/293271-
dc.description.abstractIn this study, we investigated the degradation process of metakaolin-based geopolymers exposed to high temperatures up to 1,000°C. The changes in mechanical properties, microstructure, and phase assemblage of the samples were studied, and the results demonstrated that at high temperatures the activator type [i.e., Na2SiO3/NaOH (Na/Na) and Na2SiO3/KOH (Na/K) solution] affected the degradation mechanisms of geopolymer mortars. (Na,K)-based geopolymer specimens demonstrated better thermal resistance at temperatures above 200°C. This was evident from the higher compressive strength, lower porosity, and less cracking tendency of this mixture. Compared to (Na,K)-based geopolymers, more mass loss may result in considerable drying shrinkage of (Na,Na)-based counterparts, which would further lead to the occurrence and development of cracks at ∼200°C. Above 200°C, the degradation of the mechanical properties of geopolymers could be attributed to crack development and degradation of material properties. Furthermore, compared to their (Na-Na)-based counterparts, (Na-K)-based geopolymers achieved improved chemical stability and did not form new crystalline phases above 1,000°C. Moreover, higher temperature exposure (1,000°C) led to significant sintering of geopolymers, forming a dense and homogeneous matrix and, as a result, improved mechanical properties of specimens. Overall, it showed that when specimens were exposed to different high temperatures, the mutual promoted effects between Na+ and K+ in geopolymers played a significant role in crack development, sintering, and new crystallization formation in the specimens.-
dc.languageeng-
dc.publisherAmerican Society of Civil Engineers. The Journal's web site is located at http://www.pubs.asce.org/journals/mt.html-
dc.relation.ispartofJournal of Materials in Civil Engineering-
dc.rightsJournal of Materials in Civil Engineering. Copyright © American Society of Civil Engineers.-
dc.rightsThis material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material may be found at [URL/link of abstract in the ASCE Library or Civil Engineering Database].-
dc.subjectGeopolymer mortar-
dc.subjectHigh temperature-
dc.subjectMetakaolin-
dc.subjectMicrostructure-
dc.subjectX-ray computed microtomography-
dc.titleEffects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature-
dc.typeArticle-
dc.identifier.emailYe, H: hlye@hku.hk-
dc.identifier.authorityYe, H=rp02379-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1061/(ASCE)MT.1943-5533.0003457-
dc.identifier.scopuseid_2-s2.0-85091708106-
dc.identifier.hkuros318761-
dc.identifier.volume32-
dc.identifier.spagearticle no. 04020369-
dc.identifier.epagearticle no. 04020369-
dc.identifier.isiWOS:000587485500003-
dc.publisher.placeUnited States-
dc.identifier.issnl0899-1561-

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