Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag
Alkali-activated slag is considered as a sustainable construction material due to its environmentally friendly nature. To further promote the sustainable nature of alkali-activated slag, a sodium sulfate activator is suggested to be used since it can be obtained naturally and generates lower greenho...
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doaj-ae618679dbef4c2ca210dcd446a1315e2021-08-06T15:27:53ZengMDPI AGMaterials1996-19442021-07-01144266426610.3390/ma14154266Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated SlagXiaodi Dai0Serdar Aydın1Mert Yücel Yardımcı2Karel Lesage3Geert De Schutter4Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, 9052 Ghent, BelgiumMagnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, 9052 Ghent, BelgiumMagnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, 9052 Ghent, BelgiumMagnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, 9052 Ghent, BelgiumMagnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, 9052 Ghent, BelgiumAlkali-activated slag is considered as a sustainable construction material due to its environmentally friendly nature. To further promote the sustainable nature of alkali-activated slag, a sodium sulfate activator is suggested to be used since it can be obtained naturally and generates lower greenhouse gas emissions. However, the mixtures activated by sodium sulfate exhibit low early strength and very long setting times. This study investigates the effects of calcium hydroxide (Ca(OH)<sub>2</sub>) addition on some engineering properties such as rheology, setting time, mechanical properties, porosity, and microstructure of sodium sulfate activated ground granulated blast furnace slag (GGBFS). Furthermore, the changes of chemical groups in reaction products and phase identification have been evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. Test results showed that Ca(OH)<sub>2</sub> addition can substantially increase the reaction rate and the compressive strength at early ages. In addition, the very long setting times of the sodium sulfate-activated mixtures were shortened by the addition of Ca(OH)<sub>2</sub>. SEM analysis confirmed that the incorporation of excessive amounts of Ca(OH)<sub>2</sub> could lead to a less well-packed microstructure although the reaction degree of GGBFS remained the same at later ages as compared to the sodium sulfate mixture. It was also revealed that in case of the Ca(OH)<sub>2</sub> addition into sodium sulfate activator, the main reaction products are chain-structured C-A-S-H gels and ettringite.https://www.mdpi.com/1996-1944/14/15/4266ground granulated blast furnace slagsodium sulfatecalcium hydroxidealkali-activated cements |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Xiaodi Dai Serdar Aydın Mert Yücel Yardımcı Karel Lesage Geert De Schutter |
spellingShingle |
Xiaodi Dai Serdar Aydın Mert Yücel Yardımcı Karel Lesage Geert De Schutter Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag Materials ground granulated blast furnace slag sodium sulfate calcium hydroxide alkali-activated cements |
author_facet |
Xiaodi Dai Serdar Aydın Mert Yücel Yardımcı Karel Lesage Geert De Schutter |
author_sort |
Xiaodi Dai |
title |
Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag |
title_short |
Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag |
title_full |
Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag |
title_fullStr |
Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag |
title_full_unstemmed |
Effect of Ca(OH)<sub>2</sub> Addition on the Engineering Properties of Sodium Sulfate Activated Slag |
title_sort |
effect of ca(oh)<sub>2</sub> addition on the engineering properties of sodium sulfate activated slag |
publisher |
MDPI AG |
series |
Materials |
issn |
1996-1944 |
publishDate |
2021-07-01 |
description |
Alkali-activated slag is considered as a sustainable construction material due to its environmentally friendly nature. To further promote the sustainable nature of alkali-activated slag, a sodium sulfate activator is suggested to be used since it can be obtained naturally and generates lower greenhouse gas emissions. However, the mixtures activated by sodium sulfate exhibit low early strength and very long setting times. This study investigates the effects of calcium hydroxide (Ca(OH)<sub>2</sub>) addition on some engineering properties such as rheology, setting time, mechanical properties, porosity, and microstructure of sodium sulfate activated ground granulated blast furnace slag (GGBFS). Furthermore, the changes of chemical groups in reaction products and phase identification have been evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. Test results showed that Ca(OH)<sub>2</sub> addition can substantially increase the reaction rate and the compressive strength at early ages. In addition, the very long setting times of the sodium sulfate-activated mixtures were shortened by the addition of Ca(OH)<sub>2</sub>. SEM analysis confirmed that the incorporation of excessive amounts of Ca(OH)<sub>2</sub> could lead to a less well-packed microstructure although the reaction degree of GGBFS remained the same at later ages as compared to the sodium sulfate mixture. It was also revealed that in case of the Ca(OH)<sub>2</sub> addition into sodium sulfate activator, the main reaction products are chain-structured C-A-S-H gels and ettringite. |
topic |
ground granulated blast furnace slag sodium sulfate calcium hydroxide alkali-activated cements |
url |
https://www.mdpi.com/1996-1944/14/15/4266 |
work_keys_str_mv |
AT xiaodidai effectofcaohsub2subadditionontheengineeringpropertiesofsodiumsulfateactivatedslag AT serdaraydın effectofcaohsub2subadditionontheengineeringpropertiesofsodiumsulfateactivatedslag AT mertyucelyardımcı effectofcaohsub2subadditionontheengineeringpropertiesofsodiumsulfateactivatedslag AT karellesage effectofcaohsub2subadditionontheengineeringpropertiesofsodiumsulfateactivatedslag AT geertdeschutter effectofcaohsub2subadditionontheengineeringpropertiesofsodiumsulfateactivatedslag |
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