Curing Conditions of Alkali-Activated Fly Ash and Slag Mortar
Publication: Journal of Materials in Civil Engineering
Volume 32, Issue 6
Abstract
This study compared the effect of seven common curing conditions on the compressive strength, pore alkalinity, efflorescence, and shrinkage of five alkali-activated fly ash and slag (AAFS) mortars and one cement mix. The fly ash to slag ratio and the activator content were altered in the AAFS mortars, which were then placed in the fog room, the carbonation chamber, the outside environment, bottom contact with water, and surface contact with 0%, 3.5%, and 10% sodium chloride solutions. It was found that the shrinkage was primarily a function of the dryness of the environment. The submerged curing conditions increased the extent of leaching but reduced shrinkage. For mixes with a high activator content, the effect of leaching was small. Therefore the compressive strength improved as a result of the reduced shrinkage, with the highest achieving 129.5 MPa at 56 days. The alkalinity of the curing solutions decreased as their salinity increased after 56 days of submergence. The rate of diffusion decreased as the concentration difference of the sodium cations decreased; therefore, the extent of leaching was lowered. This could incentivize the use of AAFS instead of cement, especially in highly saline underground environments.
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Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
This research was supported by an Australian Government Research Training Program (RTP) Scholarship. The authors acknowledge the facilities, and the scientific and technical assistance of Australian Microscopy and Microanalysis Research Facility at the Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. Thanks are also given to former students Mr. Luke Cannell, Mr. Jonathan Hegney and laboratory technicians Mr. Jim Waters, Mr. Brad Rose and Mr. Matt Arpin. Thanks are given to the generous support from Coogee Chemicals in Western Australia.
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Published In
Journal of Materials in Civil Engineering
Volume 32 • Issue 6 • June 2020
Copyright
©2020 American Society of Civil Engineers.
History
Received: Aug 19, 2019
Accepted: Dec 16, 2019
Published online: Mar 20, 2020
Published in print: Jun 1, 2020
Discussion open until: Aug 20, 2020
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