Paradox
Large cover depths (50–75 mm) are required to protect reinforcement against corrosion in aggressive environments, but thick cover leads to increased crack widths in flexural reinforced concrete members. Large crack-widths (greater than 0.3 mm) permit ingress of moisture and chemical attack to the concrete, resulting in possible corrosion of reinforcement and deterioration of concrete. Therefore, thick covers defeat the very purpose for which it is provided. There is a need for judicious balance of cover depth and crack width requirements.
A possible economical solution for this paradox is the placing of a second layer of corrosion-resistant reinforcement like stainless steel rebars or meshes or FRP rebars in the concrete cover to distribute the cracks.
Read more about this topic: Concrete Cover
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