HYDRATION IN HIGH-VOLUME FLY ASH CONCRETE BINDERS

This paper presents a summary of work in progress on an examination of the hydration chemistry and microstructure of a paste prepared incorporating 58 percent of a typical American Society for Testing and Materials (ASTM) Class F fly ash and a portland cement from United States sources and a paste with the portland cement only. Thermal analysis, x-ray diffraction, pore fluid extraction, and scanning electron microscope have been employed to study cement and cement-fly ash pastes cured up to 180 days. High levels of nonevaporable water and removal of alkali ions from pore solutions in pastes cured for 7 to 14 days were found. Etching of fly ash particles and extensive deposition of reaction products at ash/matrix boundaries were evident in scanning electromicrographs. Together, these observations clearly demonstrate extensive participation by the fly ash in hydration and cementation reactions. However, despite the extensive reactivity, up to 180 days, many fly ash particles remain as intact pseudomorphs embedded in the hydrate mass. A model based on siloxane and silaloxane hydrolysis, alkali ion exchange, and precipitation of calcium silicates, aluminates, and aluminosilicates, is proposed to explain the observed processes.

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  • Corporate Authors:

    American Concrete Institute

    P.O. Box 19150, Redford Station, 22400 Seven Mile Road
    Detroit, MI  United States  48219
  • Authors:
    • Berry, E E
    • HEMMINGS, R T
    • Zhang, M-H
    • Cornelius, B J
    • Golden, D M
  • Publication Date: 1994-7

Language

  • English

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Filing Info

  • Accession Number: 00667420
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 29 1994 12:00AM