Effect of Rust and Scale on the Bond
Characteristcs of Deformed Reinforcing Bars
E. L. Kemp, F. S. Brezny, and J. A. Unterspan
Appears on pages(s):
bond (concrete to reinforcement);deformed reinforcement;reinforced concrete; reinforcing steel;research;rusting;scale (corrosion).
An experimental program was established to provide needed information on bond characteristics of ASTM A 432 bars with a broad range of scale and rust conditions. The principle parameter in the test series was the bar surface conditions. It was concluded that the bond characteristics of deformed reinforcing bars with deformations meeting ASTM A 305 specifications do not appear to be adversely affected by varying degrees or types of surface rust or ordinary mill scale provided the weight of the bar meets the minimum ASTM weight and deformation height requirements. The deformation dimensions appear to govern bond characteristics of rusty bars, in that these bars exhibit a behavior similar to companion "as rolled" bars. The test data indicate that the current bond requirements are quite conservative, especially with regard to smaller bars because of the 800 psi (nom. 60 kgf/cm’) maximum stress limit. Concrete strength appears to control the over-all bond behavior, particularly slip and deformation, to a much greater extent than the surface condition of the bar.