The National Academies

NCHRP Synthesis 20-05/Topic 16-07 [Final (Synthesis)]

Use of Fly Ash in Concrete
[ NCHRP 20-05 (Synthesis of Information Related to Highway Practices) ]

  Project Data

This synthesis summarizes available information concerning the use of fly ash in hydraulic-cement concrete, and attempts to establish consensus concerning a number of applications relating to highway construction. Fly ash marketing procedures are briefly reviewed, and the amount of fly ash now being used is summarized. The results are reported of a questionnaire survey of the status of the use of fly ash concrete (FAC) in each state of the U.S. and the provinces of Canada. There is an increase in FAC use since 1980. This trend is aided by the development of a flyash industry. Trends also indicate a developing technology that will be oriented around performance of the hydraulic cement concrete. Currently, most states view the proportioning of of FAC from the standpoint of the amount of portland cement to be replaced by the fly ash and have maximum replacement limits. It has been noted that the same fly ash with different cements may react differently and develop different early and ultimate strengths. The need is emphasized for preliminary tests to establish optimum proportioning of ingredients in the concrete using materials from the sources to be supplied to the job.  The report for this topic can be purchased at http://www.trb.org/news/blurb_detail.asp?id=3430

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