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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: Early-age Bond Strength in Reinforced Concrete
Author(s): Ralph A. Chapman and Surendra P. Shah
Publication: Materials Journal
Appears on pages(s): 501-510
Keywords: age; anchorage (structural); bond (concrete to reinforcement); concrete construction; cracking (fracturing); curing; loads (forces); pullout tests; reinforced concrete; reinforcing steels; slippage; Materials Research
Abstract:An investigation was conducted to determine the bond strength between reinforcing steel and concrete loaded at early ages. Bond tests were conducted using a specially developed pullout test. Load-slip characteristics of smooth bars were compared for specimens with different bar-embedment lengths and tested at various ages from 1 to 28 days of curing. Smooth bars did not exhibit any age effect. However, the bond characteristics of deformed bars showed a significant age effect. It was observed that the ACI Code-suggested equation for development length overestimated test results for very early ages. An alternate relationship is examined for structures loaded at early ages.
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