Abstract
Due to the relatively low tensile strength of concrete, cracks are inherent in reinforced concrete structures. A common cause of cracking is the corrosion of internal steel reinforcement, a deterioration process that can affect the bond behaviour and anchorage capacity of reinforcing bars. Corrosion leads to a reduction of the reinforcing bar diameter, the formation of a weak layer of corrosion products around the bar and expansive forces on the surrounding concrete (that can lead to cracking). In the past, the impact of corrosion on bond has been investigated by means of accelerated corrosion tests. However, the more fundamental impact of cracking as distinct from corrosion products on the bond reduction is still not fully understood.This study applies a novel test method to investigate the bond behaviour of reinforcing bars in cylindrical cracked reinforced concrete specimens. The influence of the number of cracks, crack orientation, confinement and concrete cover are investigated.The results indicate a significant loss of bond strength for single cracked specimens. This reduction becomes as high as 65% for double cracked specimens in the absence of confinement. It is shown that the crack orientation with respect to the rib pattern is of minor influence, but the concrete cover and confinement play a significant role in the obtained bond characteristics.
Highlights
Concrete is an inhomogeneous material with a relatively low tensile strength
One of the most severe forms of cracking in hardened reinforced concrete structures is the result of the corrosion of steel reinforcing bars
The presence of a single crack results in a significant reduction in the ultimate bond strength of 44% (RBF = 0.56) for the tested specimens
Summary
Concrete is an inhomogeneous material with a relatively low tensile strength. It is often used in combination with steel reinforcement so that the steel can resist tensile stresses after cracking. The load bearing capacity and serviceability performance of reinforced concrete structures depend highly on the interaction between reinforcing bars and the surrounding concrete [1]. Over time the bond can degrade due to deterioration of the reinforcement and/or the surrounding concrete. When cracks develop in regions surrounding the reinforcing bars, the force transfer is. Cracks are inherent in reinforced concrete structures and are caused by a number of different types of actions [2]. One of the most severe forms of cracking in hardened reinforced concrete structures is the result of the corrosion of steel reinforcing bars. Fib bulletin No 10 [1] categorises the effects of corrosion into 3 potential consequences:
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