Effect of MgO and Na<inf>2</inf>SiO<inf>3</inf> on the carbonation resistance of alkali activated slag concrete

Khan, MSH; Castel, A

Effect of MgO and Na<inf>2</inf>SiO<inf>3</inf> on the carbonation resistance of alkali activated slag concrete

Khan, MSH Castel, A

Permalink

Publisher:: ICE PUBLISHING
Publication Type:: Journal Article
Citation:: Magazine of Concrete Research, 2018, 70, (13), pp. 685-692
Issue Date:: 2018-07-01

Closed Access

	Filename	Description	Size
	jmacr.17.00062.pdf	Published version	940.79 kB	Adobe PDF	View/Open

Copyright Clearance Process

Recently Added
In Progress
Closed Access

This item is closed access and not available.

Full metadata record

Field	Value	Language
dc.contributor.author	Khan, MSH
dc.contributor.author	Castel, A https://orcid.org/0000-0003-1619-9643
dc.date.accessioned	2022-08-27T04:22:23Z
dc.date.available	2022-08-27T04:22:23Z
dc.date.issued	2018-07-01
dc.identifier.citation	Magazine of Concrete Research, 2018, 70, (13), pp. 685-692
dc.identifier.issn	0024-9831
dc.identifier.issn	1751-763X
dc.identifier.uri	http://hdl.handle.net/10453/160919
dc.description.abstract	This paper investigates the effect of magnesium oxide (MgO) on the carbonation resistance of alkali-activated slag-fly ash blend containing 75% ground granulated blast furnace slag (GGBS) and 25% low-calcium fly ash. Two types of GGBS were used with different magnesium oxide content. Phenolphthalein indicator and pH profiles showed that the GGBS with higher levels of magnesium oxide offered no significant improvement in resistance against natural and 1% accelerated carbonation. X-ray diffraction confirmed no hydrotalcite formation, although the magnesium oxide content was 9·1%. A very small amount of free magnesium ions (Mg2+) was available in the pore solution, which was deemed insufficient to form hydrotalcite. Lack of its formation was the major reason for the lower carbonation resistance. Excessive silicate in the system reduces the calcium oxide/silicon dioxide ratio, which leads to the incorporation of magnesium ions in the calcium silicate hydrate structure. Hydrotalcite was observed when the activator concentration was reduced. The results suggest that in addition to magnesium and aluminium ion (Al3+) availability, silicate concentration also plays a strong role in deciding the hydrotalcite formation in alkali-activated GGBS concrete.
dc.language	English
dc.publisher	ICE PUBLISHING
dc.relation.ispartof	Magazine of Concrete Research
dc.relation.isbasedon	10.1680/jmacr.17.00062
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject	0905 Civil Engineering, 1202 Building
dc.subject.classification	Building & Construction
dc.title	Effect of MgO and Na<inf>2</inf>SiO<inf>3</inf> on the carbonation resistance of alkali activated slag concrete
dc.type	Journal Article
utslib.citation.volume	70
utslib.for	0905 Civil Engineering
utslib.for	1202 Building
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
utslib.copyright.status	closed_access	*
dc.date.updated	2022-08-27T04:22:23Z
pubs.issue	13
pubs.publication-status	Published
pubs.volume	70
utslib.citation.issue	13

Abstract:

This paper investigates the effect of magnesium oxide (MgO) on the carbonation resistance of alkali-activated slag-fly ash blend containing 75% ground granulated blast furnace slag (GGBS) and 25% low-calcium fly ash. Two types of GGBS were used with different magnesium oxide content. Phenolphthalein indicator and pH profiles showed that the GGBS with higher levels of magnesium oxide offered no significant improvement in resistance against natural and 1% accelerated carbonation. X-ray diffraction confirmed no hydrotalcite formation, although the magnesium oxide content was 9·1%. A very small amount of free magnesium ions (Mg2+) was available in the pore solution, which was deemed insufficient to form hydrotalcite. Lack of its formation was the major reason for the lower carbonation resistance. Excessive silicate in the system reduces the calcium oxide/silicon dioxide ratio, which leads to the incorporation of magnesium ions in the calcium silicate hydrate structure. Hydrotalcite was observed when the activator concentration was reduced. The results suggest that in addition to magnesium and aluminium ion (Al3+) availability, silicate concentration also plays a strong role in deciding the hydrotalcite formation in alkali-activated GGBS concrete.

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/160919