Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents
Alkali-activated binders based on metakaolin, fly ash and slag without curing were exposed directly in air, Na2SO4 and MgSO4 solutions for studying the evolution in mechanical strength and microstructure. A series of binders were synthesized and characterized on 7, 21, 45, 60, 75 and 90 days, respec...
Main Authors: | , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Elsevier
2020-09-01
|
Series: | Journal of Materials Research and Technology |
Subjects: | |
Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785420315386 |
id |
doaj-f19f41720f634424bee318b6e9194370 |
---|---|
record_format |
Article |
spelling |
doaj-f19f41720f634424bee318b6e91943702020-11-25T03:35:21ZengElsevierJournal of Materials Research and Technology2238-78542020-09-01951037710385Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contentsXing Li0Owen Xu Li1Feng Rao2Shaoxian Song3Noemi Ortiz-Lara4Ena A. Aguilar-Reyes5School of Zijin Mining, Fuzhou University, Fuzhou, Fujian 350108, China; CONACYT Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 58030, MexicoThe American School Foundation, Mexico City, 01120, MexicoSchool of Zijin Mining, Fuzhou University, Fuzhou, Fujian 350108, China; CONACYT Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 58030, Mexico; Corresponding author at: School of Zijin Mining, Fuzhou University, Fuzhou, Fujian 350108, China.School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, ChinaCONACYT Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 58030, MexicoCONACYT Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 58030, MexicoAlkali-activated binders based on metakaolin, fly ash and slag without curing were exposed directly in air, Na2SO4 and MgSO4 solutions for studying the evolution in mechanical strength and microstructure. A series of binders were synthesized and characterized on 7, 21, 45, 60, 75 and 90 days, respectively. Compressive strength measurement, scanning electron microscope (SEM) mapping, X-ray diffraction (XRD) and unclear magnetic resonance (NMR) were applied in the study. It is found that the exposure in sulfate solutions leaded to the deterioration of the binders by the dissolution of alkalis. In Na2SO4 solution, a higher percentage of zeolite was formed in the binders. While in MgSO4, a precipitate layer (e.g., brucite and gypsum), forming on the binder surface plays an important role in protecting the formation of gel, promoting the compressive strength improvement of alkali-activated slag, and compensating the decrease in compressive strength of alkali-activated metakaolin. These results provide clues for the direct preparation of alkali-activated concrete in aggressive sulfate environment.http://www.sciencedirect.com/science/article/pii/S2238785420315386Alkali-activated binderSulfate solutionCompressive strengthN-A-S-H gelNMR spectra |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Xing Li Owen Xu Li Feng Rao Shaoxian Song Noemi Ortiz-Lara Ena A. Aguilar-Reyes |
spellingShingle |
Xing Li Owen Xu Li Feng Rao Shaoxian Song Noemi Ortiz-Lara Ena A. Aguilar-Reyes Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents Journal of Materials Research and Technology Alkali-activated binder Sulfate solution Compressive strength N-A-S-H gel NMR spectra |
author_facet |
Xing Li Owen Xu Li Feng Rao Shaoxian Song Noemi Ortiz-Lara Ena A. Aguilar-Reyes |
author_sort |
Xing Li |
title |
Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
title_short |
Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
title_full |
Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
title_fullStr |
Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
title_full_unstemmed |
Microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
title_sort |
microstructural evolution in sulfate solutions of alkali-activated binders synthesized at various calcium contents |
publisher |
Elsevier |
series |
Journal of Materials Research and Technology |
issn |
2238-7854 |
publishDate |
2020-09-01 |
description |
Alkali-activated binders based on metakaolin, fly ash and slag without curing were exposed directly in air, Na2SO4 and MgSO4 solutions for studying the evolution in mechanical strength and microstructure. A series of binders were synthesized and characterized on 7, 21, 45, 60, 75 and 90 days, respectively. Compressive strength measurement, scanning electron microscope (SEM) mapping, X-ray diffraction (XRD) and unclear magnetic resonance (NMR) were applied in the study. It is found that the exposure in sulfate solutions leaded to the deterioration of the binders by the dissolution of alkalis. In Na2SO4 solution, a higher percentage of zeolite was formed in the binders. While in MgSO4, a precipitate layer (e.g., brucite and gypsum), forming on the binder surface plays an important role in protecting the formation of gel, promoting the compressive strength improvement of alkali-activated slag, and compensating the decrease in compressive strength of alkali-activated metakaolin. These results provide clues for the direct preparation of alkali-activated concrete in aggressive sulfate environment. |
topic |
Alkali-activated binder Sulfate solution Compressive strength N-A-S-H gel NMR spectra |
url |
http://www.sciencedirect.com/science/article/pii/S2238785420315386 |
work_keys_str_mv |
AT xingli microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents AT owenxuli microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents AT fengrao microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents AT shaoxiansong microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents AT noemiortizlara microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents AT enaaaguilarreyes microstructuralevolutioninsulfatesolutionsofalkaliactivatedbinderssynthesizedatvariouscalciumcontents |
_version_ |
1724554883133079552 |