Preparation of shrinkage-free alkali-activated slag material using MgO as both the activator and the expansive agent

P.  Chen; Q.  Chen; Y.  Fang; C.  Wang; X.  Wang; J.  Li; Y.  Wang

doi:10.3989/mc.2023.297022

Authors

P. Chen School of Civil Engineering and Architecture, Anhui University of Science and Technology - Institute of Environment-friendly Materials and Occupational Health, Anhui University of Science and Technology - Anhui Hongchang New Material Co. Ltd https://orcid.org/0000-0002-5538-617X
Q. Chen College of Mechanics and Materials, Hohai University https://orcid.org/0000-0001-6623-9696
Y. Fang College of Mechanics and Materials, Hohai University https://orcid.org/0000-0002-2047-9931
C. Wang School of Civil Engineering and Architecture, Anhui University of Science and Technology https://orcid.org/0000-0002-1169-5130
X. Wang School of Civil Engineering and Architecture, Anhui University of Science and Technology https://orcid.org/0000-0002-6196-4968
J. Li School of Civil Engineering and Architecture, Anhui University of Science and Technology https://orcid.org/0000-0001-9914-5944
Y. Wang School of Civil Engineering and Architecture, Anhui University of Science and Technology https://orcid.org/0000-0003-4992-7205

DOI:

https://doi.org/10.3989/mc.2023.297022

Keywords:

Alkali-activated slag, MgO, Autogenous shrinkage, Drying shrinkage

Abstract

Alkali-activated slag (AAS) materials activated by NaOH or waterglass has been long-term criticized for the developed substantial shrinkage. To this regard, this paper explored MgO as both an activator and an expansive agent to prepare shrinkage-free AAS. The setting time, mechanical strength, pore structure, autogenous shrinkage, drying shrinkage, and hydration products of MgO-activated AAS were studied. Experimental results confirmed that MgO can effectively mitigate the autogenous shrinkage and drying shrinkage of AAS via the expansive deformation caused by Mg(OH)₂. Generally, AAS with a higher dosage of MgO developed less shrinkages and refiner pore structures with more gel pores. An optimal dosage of 9% MgO is recommended to prepare AAS with near zero shrinkage and the highest flexural strength.

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