In situ synchrotron X-ray pair distribution function analysis of the early stages of gel formation in metakaolin-based geopolymers

Claire Emily White, Katharine Page, Neil J. Henson, John L. Provis

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

The nanostructural evolution of metakaolin-based geopolymer binders is investigated using in situ X-ray pair distribution function analysis. This technique enables individual atom-atom correlations present in the system to be identified and followed as the reaction proceeds. By changing the activator nature and concentration, it is revealed that free silica in the activating solution enhances the dissolution of metakaolin during the initial stages of reaction (over the initial 10. h). However, at later stages the extent of reaction is reduced significantly for the silicate-activated system due to the more dense gel morphology preventing further metakaolin dissolution and framework structure reorganization. The formation of 4-membered aluminosilicate rings in the binder structure is particularly notable in the in situ PDF data sets, showing the point at which the binder begins to become more closely crosslinked. The nanostructural role of calcium in blended metakaolin-slag geopolymer binders is also able to be described by the application of this technique. Quantification of the nanostructural changes taking place during the formation of geopolymer binders (up to 128. days) enables elucidation of the impact of mix design parameters on the resulting aluminosilicate gel nanostructure.

Original languageEnglish (US)
Pages (from-to)17-25
Number of pages9
JournalApplied Clay Science
Volume73
Issue number1
DOIs
StatePublished - Mar 1 2013

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Keywords

  • Aluminosilicate
  • Geopolymer
  • Metakaolin
  • Pair distribution function
  • Slag
  • Total scattering

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