Effect of calcium-silicon ratio on microstructure and nanostructure of calcium silicate hydrate synthesized by reaction of fumed silica and calcium oxide at room temperature

Yongjia He, Linnu Lu, Leslie J. Struble, Jennifer L. Rapp, Paramita Mondal, Shuguang Hu

Research output: Contribution to journalArticlepeer-review

Abstract

A C-S-H series with calcium-silicon ratio 0.6-3.0 was synthesized by pozzolanic reaction. Phase composition, nanostructural and morphological characteristics were determined using XRD, XRF, SEM and 29Si NMR. Most of the samples were phase-pure, poorly crystalline C-S-H. Significant changes in the nanostructure of the C-S-H samples were observed when the calcium-silicon ratio reached values of 0.8, 1.0 and 1.5. At calcium-silicon ratio 0.8 the basal XRD peak began to develop, crosslinking between layers was seen below this ratio but not above, and there was a substantial decrease in mean silica chain length at this ratio. At calcium-silicon ratio 1.0 there was a pronounced microstructural change from granular to reticular and another substantial decrease in mean chain length (indicated by an abrupt increase in the Q1 peak intensity and decrease in the Q2 peak intensity). At calcium-silicon ratio 1.5 the basal XRD peak began to diminish again, the mean silica chain length decreased further, and isolated tetrahedra (Q0) were observed.

Original languageEnglish (US)
Pages (from-to)311-322
Number of pages12
JournalMaterials and Structures/Materiaux et Constructions
Volume47
Issue number1-2
DOIs
StatePublished - Jan 2014

Keywords

  • Calcium silicate hydrate (C-S-H)
  • Calcium-silicon ratio
  • Microstructure
  • NMR
  • Nanostructure
  • SEM
  • XRD

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science(all)
  • Mechanics of Materials

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