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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Modification of the Compressive Strength Requirements for the ASTM C494 Standard on Chemical Admixtures
Author(s): Ara A. Jeknavorian and Philip J. Press
Publication: Special Publication
Appears on pages(s): 1-15
Keywords: ASTM C494; chemical admixture; compressive strength; performance requirements; statistical analysis.
Abstract:The original version of the ASTM C494 Standard Specification for Chemical Admixtures for Concrete required that new chemical admixture formulations meet 6-month and 1-year compressive strength criteria in order to be in compliance with this standard. In 2005, the ASTM C09 committee approved that selected types of chemical admixtures could qualify for provisional compliance when a set of statistically determined alternative compressive strength requirements are met. The alternate requirements would allow the new chemical admixture products, normally incorporating newer technologies, to be more readily accepted by those agencies requiring ASTM C494 compliance. Under the auspices of the ASTM C09.23 Sub-committee on Chemical Admixtures, 103 sets of compressive strength data provided by five chemical admixture companies were statistically analyzed to determine the capability of 28-day and 6-month results to predict a later age strength. The results indicate that 6-month and 1-year compressive strength results, expressed as percent of reference mix strength, can be predicted with reasonable precision from early strength results. In particular, 28-day strength (% of ref) can be used to predict 6-month and 1-year strengths (% of ref) within the accuracy of measurement of compressive strength. Further¬more, the data indicate that 1-year compressive strength, as a % of reference mix, is not significantly different from 6-month strength, as a % of reference mix.
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