ALKALI-SILICA REACTIVITY OF LARGE SILICA FUME-DERIVED PARTICLES

This paper describes how pozzolanic materials, including silica fume, are commonly added to concrete to reduce expansion because of alkali-silica reaction (ASR). However, it has been noted that commercial silica fume is not always adequately dispersed, and large agglomerates may be present. These large particles have been hypothesized to act as amorphous silica aggregates, thereby participating in an expansive reaction with the alkalis present in cement paste pore solution. If such were the case, some silica fume particles would actually aggravate expansion due to ASR rather than suppress it. The present investigation characterizes the microstructure and morphology of agglomerated and sintered silica fume particles and compares their effects on alkali-silica-related expansion. While a 5% replacement of moderately reactive sand with sintered silica fume aggregates caused significant expansion under accelerated testing conditions (modified ASTM C1260), the replacement with large agglomerates of densified silica fume decreased expansion compared with control mortar bars containing only sand. Both the sintered aggregates and the agglomerates reacted with the pore solution; one reaction was expansive, while the other was not.

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• Corporate Authors:

  Elsevier

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  Kidlington, Oxford  United Kingdom  OX5 1GB
• Authors:
  • Juenger, MCG
  • Ostertag, C P
• Publication Date: 2004-8

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: 24 p.
• Serial:
  • Cement and Concrete Research
  • Volume: 34
  • Issue Number: 8
  • Publisher: Elsevier
  • ISSN: 0008-8846
  • Serial URL: http://www.sciencedirect.com/science/journal/00088846

Subject/Index Terms

• TRT Terms: Aggregates; Alkali silica reactions; Expansion; Microstructure; Mortar; Particles; Pore pressure; Pozzolan; Reactions in concrete; Sand; Silica fume; Sintering
• Subject Areas: Geotechnology; Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 00983078
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 9 2004 12:00AM