Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste

Jin, F. , Gu, K. and Al-Tabbaa, A. (2014) Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste. Construction and Building Materials, 51, pp. 395-404. (doi:10.1016/j.conbuildmat.2013.10.081)

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Abstract

Conventional alkali-activated slag (AAS) cements suffer from significant drying shrinkage which hinders their widespread application. This paper investigates the potential of using commercial reactive MgO to reduce the drying shrinkage of AAS. Two different reactive MgOs were added at a content of 2.5–7.5 wt% of the slag, which was activated by sodium hydroxide and water–glass. The strength and the drying shrinkage of those reactive MgO modified AAS (MAAS) pastes were measured up to 90 days. It is found that MgO with high reactivity accelerated the early hydration of AAS, while MgO with medium reactivity had little effect. The drying shrinkage was significantly reduced by highly reactive MgO but it also generated severe cracking under the dry condition. On the other hand, medium-reactive MgO only showed observable shrinkage-reducing effect after one month, but the cement soundness was improved. The hydration products, analysed by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy techniques, showed that Mg was mainly incorporated in the hydrotalcite-like phases. It is concluded that the curing conditions and the time of hydrotalcite-like phases formation and their quantity are crucial to the developed strength and shrinkage reduction properties of MAAS, which are highly dependent on the reactivity and content of reactive MgO.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Jin, Dr Fei
Authors: Jin, F., Gu, K., and Al-Tabbaa, A.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Construction and Building Materials
Publisher:Elsevier
ISSN:0950-0618
ISSN (Online):1879-0526
Published Online:28 November 2013

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