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Title: Distinctive microstructural features of aged sodium silicate-activated slag concretes

Electron microscopic characterisation of 7-year old alkali-activated blast-furnace slag concretes enabled the identification of distinct microstructural features, providing insight into the mechanisms by which these materials evolve over time. Backscattered electron images show the formation of Liesegang-type ring formations, suggesting that the reaction at advanced age is likely to follow an Oswald supersaturation–nucleation–depletion cycle. Segregation of Ca-rich veins, related to the formation of Ca(OH){sub 2}, is observed in microcracked regions due to the ongoing reaction between the pore solution and available calcium from remnant slag grains. A highly dense and uniform interfacial transition zone is identified between siliceous aggregate particles and the alkali activated slag binders, across the concretes assessed. Alkali-activated slag concretes retain a highly dense and stable microstructure at advanced ages, where any microcracks induced at early ages seem to be partially closing, and the remnant slag grains continue reacting.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [5] ;  [2]
  1. Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia)
  2. Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD (United Kingdom)
  3. (Colombia)
  4. School of Materials Engineering, Composite Materials Group, Universidad del Valle, Cali (Colombia)
  5. (Australia)
Publication Date:
OSTI Identifier:
22395927
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 65; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BLAST FURNACES; CALCIUM; CONCRETES; MICROSTRUCTURE; PARTICLES; SCANNING ELECTRON MICROSCOPY; SLAGS; SODIUM SILICATES; SOLUTIONS; SUPERSATURATION