Bond of Reinforcement to Revibrated Concrete

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Title: Bond of Reinforcement to Revibrated Concrete

Author(s): Wilsam A. K. Altowaiji, David Darwin, and Rex C. Donahey

Publication: Journal Proceedings

Volume: 83

Issue: 6

Appears on pages(s): 1035-1042

Keywords: bond (concrete to reinforcement); concrete construction; consolidation; cover; reinforced concrete; reinforcing steels; revibration; vibration; workability.

Date: 11/1/1986

Abstract:
The effects of revibration on concrete-steel bond strength are studied. Key variables are concrete slump, bar position, and the time interval between initial vibration and revibration. No. 8 (25 mm) deformed reinforcing bars were used with a 2 in. (51 mm) cover and a 10 in. (254 mm) bonded length. Concrete slumps ranged from 2 3/4 in. to 7 « in. (70 to 190 mm). Two specimen depths were used. All specimens were modified cantilever beam specimens. The experimental results show that revibration is not universally beneficial to concrete-steel bond. Revibration appears to improve bond strength for top-cast bars placed in high-slump concrete. Revibration may, however, severely damage bond strength for bars cast in well-consolidated, low-slump concrete. Revibration is almost universally detrimental to the bond strength of bottom-cast bars. Overall, revibration tends to reduce the differences in bond strength caused by differences in slump and bar position.