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Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests

Metakaolin was used as a raw material for the preparation of geopolymers, where two types of alkali activators (Na(2)SiO(3) + NaOH and Na(2)SiO(3) + NaOH) were used to prepare metakaolin geopolymers at room temperature. The mechanical properties and microstructures of the metakaolin geopolymers were...

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Autores principales: Dai, Shoushuai, Wang, Hongguang, An, Shuai, Yuan, Long
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9030422/
https://www.ncbi.nlm.nih.gov/pubmed/35454650
http://dx.doi.org/10.3390/ma15082957
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author Dai, Shoushuai
Wang, Hongguang
An, Shuai
Yuan, Long
author_facet Dai, Shoushuai
Wang, Hongguang
An, Shuai
Yuan, Long
author_sort Dai, Shoushuai
collection PubMed
description Metakaolin was used as a raw material for the preparation of geopolymers, where two types of alkali activators (Na(2)SiO(3) + NaOH and Na(2)SiO(3) + NaOH) were used to prepare metakaolin geopolymers at room temperature. The mechanical properties and microstructures of the metakaolin geopolymers were analyzed. A three-factor, four-level orthogonal test was designed to investigate the mechanical properties of the metakaolin geopolymer with different ratios. The compressive and flexural strength of different specimens were tested for 7 and 28 days. Both the Na-based and K-based geopolymers exhibited excellent mechanical properties, but the K-based geopolymer had better mechanical properties. The optimal compressive strength and flexural strength of the K-based geopolymer were 73.93 MPa and 9.37 MPa, respectively. The 28-day optimal compressive strength of the Na-based polymer was 65.79 MPa, and the flexural strength was 8.71 MPa. SEM, XRD, and FTIR analyses showed that the mechanical properties of the geopolymers could be greatly improved by using a higher alkaline solution concentration, proper Na(2)SiO(3)/MOH mass ratio, and proper mass ratio of alkali exciter to metakaolin. Amorphous silicoaluminate was more favorable for the dissolution of silicon–alumina raw materials, promoted the formation of an amorphous silicoaluminate gel, and caused the internal structure of the geopolymer to be more compact.
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spelling pubmed-90304222022-04-23 Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests Dai, Shoushuai Wang, Hongguang An, Shuai Yuan, Long Materials (Basel) Article Metakaolin was used as a raw material for the preparation of geopolymers, where two types of alkali activators (Na(2)SiO(3) + NaOH and Na(2)SiO(3) + NaOH) were used to prepare metakaolin geopolymers at room temperature. The mechanical properties and microstructures of the metakaolin geopolymers were analyzed. A three-factor, four-level orthogonal test was designed to investigate the mechanical properties of the metakaolin geopolymer with different ratios. The compressive and flexural strength of different specimens were tested for 7 and 28 days. Both the Na-based and K-based geopolymers exhibited excellent mechanical properties, but the K-based geopolymer had better mechanical properties. The optimal compressive strength and flexural strength of the K-based geopolymer were 73.93 MPa and 9.37 MPa, respectively. The 28-day optimal compressive strength of the Na-based polymer was 65.79 MPa, and the flexural strength was 8.71 MPa. SEM, XRD, and FTIR analyses showed that the mechanical properties of the geopolymers could be greatly improved by using a higher alkaline solution concentration, proper Na(2)SiO(3)/MOH mass ratio, and proper mass ratio of alkali exciter to metakaolin. Amorphous silicoaluminate was more favorable for the dissolution of silicon–alumina raw materials, promoted the formation of an amorphous silicoaluminate gel, and caused the internal structure of the geopolymer to be more compact. MDPI 2022-04-18 /pmc/articles/PMC9030422/ /pubmed/35454650 http://dx.doi.org/10.3390/ma15082957 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Dai, Shoushuai
Wang, Hongguang
An, Shuai
Yuan, Long
Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title_full Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title_fullStr Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title_full_unstemmed Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title_short Mechanical Properties and Microstructural Characterization of Metakaolin Geopolymers Based on Orthogonal Tests
title_sort mechanical properties and microstructural characterization of metakaolin geopolymers based on orthogonal tests
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9030422/
https://www.ncbi.nlm.nih.gov/pubmed/35454650
http://dx.doi.org/10.3390/ma15082957
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