High-Percentage Replacement of Cement with Fly Ash for Reinforced Concrete Pipe

A high percentage of the cement within concrete can be replaced by fly ash (a by-product of coal-fired electric power plants) without adversely affecting concrete properties for specific applications. However, the resulting concrete may have such low workability that it is unusable in common manufacturing processes. This article reports on a study of the use of high-percentage replacement of cement with fly ash for reinforced concrete pipe. In this study, test cylinders with varying percentages of Class C (25-65%) and Class F (25-75%) fly ash and a water-reducing admixture (WRA) were created under field manufacturing conditions and tested for 7-day compressive strength. Seven-day compressive strength for the concrete/fly ash/WRA was found to be highest when the concrete mix included approximately 35% Class C or 25% Class F fly ash. However, substitution ratios of up to 65% Class C or 40% Class F fly ash for cement met or exceeded American Society for Testing and Materials (ASTM) strength requirements for manufacture of Class I, II and III reinforced concrete pipe (RCP). The benefits of replacing cement with fly ash in the manufacture of RCP include: decreased permeability of concrete, improved workability, improved resistance of RCP to weak acids and sulfates, increased service life of pipe production equipment (due to the lubricating effects of fly ash), increased cohesiveness of concrete for early form removal, and reduced amount of inside surface hairline cracking due to decreased heat of hydration. The authors conclude that a small increase in the percentage of fly ash used in the manufacture of RCP could provide significant benefits, both economically and in quality of product.

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  • Authors:
    • Berryman, Charles
    • Zhu, Jingyi
    • Jensen, Wayne
    • Tadros, Maher
  • Publication Date: 2005-6


  • English

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  • Accession Number: 01002957
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 3 2005 9:20AM