Abstract
The paper presents experimental investigations of the concrete covers’ protective ability to counteract rebar corrosion in reinforced concrete cubes. The concrete sample was subjected to a chloride-induced environment to get corroded and combined with an un-corroded sample. The chloride-accelerated technique can induce a high degree of corrosion within a controlled time. Moreover, detailed and thorough experimental measurements and analyses of reinforcement loss due to corrosion and its influence on concrete microstructure, were studied through 3D X-ray micro-computed tomography. The rebar outside the concrete was heavily corroded due to the chloride-accelerated test, whereas, only local surface corrosion products appeared inside the concrete. It turned out that the concrete cover showed protective ability to counteract the reinforcing-steel corrosion mechanism despite the accelerated corrosion environment. Moreover, the bond strength between the reinforcement rebar and concrete was not visibly affected since the failure force in the pull-out test and failure mechanisms, observed by 3D X-ray micro-CT, were similar for corroded and un-corroded samples. The failure occurred due to radial cracks with a maximum width equal to approximately 0.25 mm.
Highlights
The latest reports have shown significant economic impact due to the negative influence of corrosion
Steel reinforcement is protected by a passive layer on its surface and concrete cover
The results demonstrated that the developed capacitive sensor could be highly effective for determining the thickness of the rust layer of various rebar
Summary
The latest reports have shown significant economic impact due to the negative influence of corrosion. Some countries are forced to spend money on repairing and maintaining steel and RC structures [1,2]. Corrosion of reinforcement leads to the weakening of the bond strength, resulting in the deterioration of the structural integrity. As a result of corrosion, the initial cross-section of the reinforcement is reduced, which weakens the mechanical properties of the steel bar. Tensile stresses in the concrete cover, caused by the oxides on the corroded steel, lead to loss of the bond mechanism. The high alkalinity of concrete (pH ~ 13.0) protects the steel due to a passive zone of ferric oxides. Steel reinforcement is protected by a passive layer on its surface and concrete cover. The uncracked concrete cover is a physical barrier for corrosive factors delaying their diffusion through the concrete pores towards the reinforcement. Chlorides enter the concrete pore network by diffusion or capillary suction or combining the mechanisms as mentioned above [3]
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