Comparative Analysis of the Influence of Sodium and Potassium Silicate Solutions on the Kinetics and Products of Slag Activation

Akash Dakhane, Zihui Peng, Robert F Marzke, Narayanan Neithalath

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

This paper primarily explores the influence of the alkali cation (Na or K) on the reaction kinetics, product formation, gel structure, and mechanical properties of alkali activated slag systems. For the same activator Ms, i.e., molar SiO2-M2O ratio (M=Na or K), a shorter induction period, a larger acceleration peak, and consequently, a higher amount of total heat release under isothermal conditions is observed for the K-silicate activated slag pastes. The early-age compressive strengths in these systems roughly relate to the heat release response. The later-age (7 days and beyond) compressive strengths are observed to be higher for the Na-silicate activated systems, which is corroborated by: (1) higher amounts of C-(A)-S-H gel in this system indicated by a thermal analysis-based approximate quantification method, and (2) higher combined intensities of Q1 and Q2 structures that point to increased degrees of reaction, and lower amounts of unreacted slag obtained from 29Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra also show evidences of Al-substituted C-S-H gel, with a higher amount of substitution when Na-silicates are used.

Original languageEnglish (US)
Pages (from-to)371-387
Number of pages17
JournalAdvances in Civil Engineering Materials
Volume3
Issue number1
DOIs
StatePublished - Dec 31 2014

Keywords

  • alkali activation
  • cationic type
  • isothermal calorimetry
  • NMR spectroscopy
  • slag
  • thermal analysis

ASJC Scopus subject areas

  • Ceramics and Composites
  • Civil and Structural Engineering
  • Mechanics of Materials
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry

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