Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates

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  • C. Ruiz-Santaquiteria, Eduardo Torroja Institute (CSIC)
  • ,
  • J. Skibsted
  • A. Fernández-Jiménez, Eduardo Torroja Institute (CSIC)
  • ,
  • A. Palomo, Eduardo Torroja Institute (CSIC)
This study investigates the effect of the alkaline solution/binder (S/B) ratio on the composition and nanostructure of the reaction products generated in the alkaline activation of aluminosilicates. The experiments used two mixtures of fly ash and dehydroxylated white clay and for each of these, varying proportions of the solution components. The alkali activator was an 8 M NaOH solution (with and without sodium silicate) used at three S/B ratios: 0.50, 0.75 and 1.25. The Si, Al MAS NMR and XRD characterisation of the reaction products reveal that for ratios nearest the value delivering suitable paste workability, the reaction-product composition and structure depend primarily on the nature and composition of the starting materials and the alkaline activator used. However, when an excess alkaline activator is present in the system, the reaction products tend to exhibit SiO /Al O ratios of approximately 1, irrespective of the composition of the starting binder or the alkaline activator.
Original languageEnglish
JournalCement and Concrete Research
Pages (from-to)1242-1251
Number of pages10
Publication statusPublished - 1 Sep 2012

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