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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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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: In Situ Tests: Variability and Strength Prediction of Concrete at Early Ages
Author(s): G.G. Carette and V.M. Malhotra
Publication: Special Publication
Appears on pages(s): 111-142
Keywords: age-strength relation;
cores; form removal; fresh concre
nondestructive tests; penetration
compressive strength; concrete
tes; impact hammer tests;
tests; pullout tests; ultrasonic
Abstract:This paper reports on an investigation undertaken to determine the within-test variability at the ages of 1 to 3 days of various in-situ tests cur-rently being used in the field, and to determine their ability to predict early-age strength development of concrete for formwork removal purposes. The methods investigated included penetration resistance, pulse velocity, rebound number and two types of pullout tests. The tests were performed at 1, 2 and 3 days on plain concrete slabs, 300 x 1220 x 1220 mm in size. I The test results indicate that the pulse velocity method had the least variability with a within-test coefficient of variation of less than 0.5% whereas the rebound method had the highest variability with anaverage coefficient of variation in the order of 12%. The values for other in-situ tests ranged from 5 to 10%. It is concluded that all in-situ tests, with the exception of the rebound method, can predict the early-age strength development of concrete within a reasonable degree of accuracy, and thus can be applied to determine 5 safe stripping times for removal of formwork in concrete construction.
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