Estimating efficiency of fly ashes: An alternative definition of K values

Nishant Garg, Kejin Wang

Research output: Contribution to journalArticlepeer-review


Assessment of fly ash efficiency based on the mechanical performance of fly ashmodified mortars is not straightforward. Hence, a ‘k value’, or an efficiency factor, of various forms have been proposed and employed in the past. In this study, a simplified k* value analysis is proposed to handle large sets of compressive strength data. A set of six fly ashes from different sources across the USA were collected and analyzed in this study to gauge their efficiency. In a comparison of fly ash with an ideal inert material (rather than with commonly used Portland cement), the k* values, or reactivity levels of fly ashes, reported here are dependent on the replacement level and independent of curing age. Such an analysis may be beneficial to industrial concrete labs where significant amount of trial batches and mixes are prepared prior to the commercial employment of a new fly ash or pozzolan.

Original languageEnglish (US)
Pages (from-to)25-33
Number of pages9
JournalJournal of Sustainable Cement-Based Materials
Issue number1
StatePublished - 2015
Externally publishedYes


  • Compressive strength
  • Efficiency
  • Fly ash
  • High volume fly ash concrete
  • K value analysis

ASJC Scopus subject areas

  • Ceramics and Composites
  • Waste Management and Disposal


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