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Title: The role of alumina on performance of alkali-activated slag paste exposed to 50 °C

The strength and microstructural evolution of two alkali-activated slags, with distinct alumina content, exposed to 50 °C have been investigated. These two slags are ground-granulated blast furnace slag (containing 13% (wt.) alumina) and phosphorous slag (containing 3% (wt.) alumina). They were hydrated in the presence of a combination of sodium hydroxide and sodium silicate solution at different ratios. The microstructure of the resultant slag pastes was assessed by X-ray diffraction, differential thermogravimetric analysis, and scanning electron microscopy. The results obtained from these techniques reveal the presence of hexagonal hydrates: CAH{sub 10} and C{sub 4}AH{sub 13} in all alkali-activated ground-granulated blast-furnace slag pastes (AAGBS). These hydrates are not observed in pastes formed by alkali-activated ground phosphorous slag (AAGPS). Upon exposure to 50 °C, the aforementioned hydration products of AAGBS pastes convert to C{sub 3}AH{sub 6}, leading to a rapid deterioration in the strength of the paste. In contrast, no strength loss was detected in AAGPS pastes following exposure to 50 °C. -- Highlights: •Strength of alkali-activated slag (AAS) pastes after exposure to 50 °C is studied. •AAS pastes with high alumina content lose strength after the exposure. •C{sub 4}AH{sub 13} and CAH{sub 10} form in these AAS pastes. •Conversion of thesemore » calcium alumina hydrates is associated with the strength loss. •AAS pastes with low alumina content maintain its strength after the exposure.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ; ; ;  [1]
  1. Department of Civil Engineering, Monash University, Clayton, Victoria 3800 (Australia)
  2. Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria (Australia)
  3. School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009 (Australia)
  4. School of Geosciences and Info-Physics, Central South University, Changsha 410083 (China)
Publication Date:
OSTI Identifier:
22220829
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 54; Other Information: Copyright (c) 2013 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; ABSORPTION SPECTROSCOPY; ALUMINIUM OXIDES; BLAST FURNACES; SCANNING ELECTRON MICROSCOPY; SLAGS; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION