While steel reinforcement solves one of concrete greatest limitations, it creates an entirely new problem: Corrosion of embedded steel rebar is the most common form of concrete deterioration.
Reinforcing bars in concrete area unit shielded from corrosion by a skinny chemical compound layer that forms on their surface because of the high alkalinity, i.e., the high hydrogen ion concentration price, of the encompassing concrete. Corrosion might begin once this protecting layer is destroyed, either by chloride penetration or because of a discount within the hydrogen ion concentration price of concrete to values below regarding nine.

Causes of rust:
• Rust occurs due to cracking of the protective layer (concrete cover) and the appearance of rust on the surface of the reinforcing steel
• Rusting of the reinforcing steel begins in a small click in the Sikhs, and then this increase becomes more common, resulting in general rust
There are several factors that break this class:
1- Carbonization due to the atmosphere surrounding the concrete.
2 - Attack of chlorides of concrete (from the soil or due to non-use of water suitable for mixing)
3 - entering the salts to the concrete
How can iron protect from rust?
There are different ways to protect reinforcing steel from rust, the most important of which are:
1. Cathodic protection is the best method for coastal enterprises, but it is expensive to do so. It is preferable to conduct a study to choose the method that meets the purpose.
2. Adding some materials to the cement to reduce its permeability, which is less expensive method of cathodic protection, but the age of protection is lower.
3. Use of rust inhibitors: the first type depends on the work of protection around the reinforcing steel and the other type to prevent the penetration of oxygen inside the concrete.

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