Title:
Early-age Bond Strength in Reinforced Concrete
Author(s):
Ralph A. Chapman and Surendra P. Shah
Publication:
Materials Journal
Volume:
84
Issue:
6
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
DOI:
10.14359/2438
Date:
11/1/1987
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.