Effect of Calcium Additions on N-A-S-H Cementitious Gels

Ines Garcia-Lodeiro, Ana Fernandez-Jimenez, Angel Palomo, Donald E. Macphee

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Abstract

This paper reports a research on the properties of synthetic sodium aluminosilicate hydrate gels as models for the gels arising in alkali-activated aluminosilicate systems. The interaction between these N-A-S-H gels and aqueous calcium was studied to explore a potential consequence of mixing conventional Portland cements and alkali-activated systems. The properties of two N-A-S-H gels (with Si/Al=1 and 2) synthesized in highly alkaline media, in the presence of calcium are reported. N-A-S-H gels were synthesized using aluminum nitrate, sodium hydroxide, and a sodium silicate. FTIR, NMR, and TEM/EDX techniques were used to characterize N-A-S-H gels before and after adding calcium. The results obtained show that calcium is uptaken in N-A-S-H gels resulting in a modification of the chemical composition due to the substitution of sodium per calcium.

Original languageEnglish
Pages (from-to)1934-1940
Number of pages7
JournalJournal of the American Ceramic Society
Volume93
Issue number7
Early online date12 Mar 2010
DOIs
Publication statusPublished - Jul 2010

Keywords

  • fly-ash
  • silicate hydrate
  • part 1
  • geopolymers
  • temperature
  • activation
  • cations
  • systems
  • FTIR

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