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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Mater. | doi: 10.3389/fmats.2019.00287

Effects of curing conditions on shrinkage of Alkali-Activated High-MgO Swedish Slag Concrete

  • 1Building materials division, Luleå University of Technology, Sweden
  • 2University of Babylon, Iraq
  • 3Department of Materials Science and Engineering, University of Sheffield, United Kingdom

This study aimed to determine the effects of curing regime on shrinkage of alkali-activated concretes produced from a Swedish high-MgO blast furnace slag. Sodium carbonate (SC), sodium silicate (SS) and their combination were used as alkali activators. The studied curing procedure included heat-treatment, no heat-treatment, sealed and non-sealed conditions. The heat curing increased the compressive strengths of the concretes activated with SS and with the combination of SS and SC. Sealed-curing applied for a period of one month reduced the measured drying shrinkage by up to 50% for all studied heat-treated samples. Conversely, the same curing procedure significantly increased the development of the drying shrinkage once the seal was removed after 28 days of curing in the case of the SC-activated concretes non-heat treated. Higher degree of reaction/hydration reached by the binders in these concretes was indicated as the main factor. All of the concretes studied had showed a significant microcracking of the binder matrix, with the most extensive cracking observed in the sealed lab-cured mixes. The heat-cured mixes activated with SS and combination of SC and SS showed the most homogenous microstructure and low extensive micro cracking comparing with lab-cured ones.

Keywords: Alkali activated slag concrete, alkali activated slag microstructure, Drying shrinkage, Curing regime, high MgO granulated blast furnace slag

Received: 19 May 2019; Accepted: 29 Oct 2019.

Copyright: © 2019 Humad, Provis and Cwirzen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mrs. Abeer M. Humad, Luleå University of Technology, Building materials division, Luleå, Sweden, abeer.humad@ltu.se