4.3. Causes of Corrosion

Try these first

1. 1.

   Define corrosion in the context of concrete.

   Hint

   Think about how metals react with their environment.

2. 2.

   Name one cause of corrosion.

   Hint

   Remember the processes affecting the protective layer.

3. 3.

   What chemical reaction starts the process of carbonation?

   • CO₂ + H₂O → H₂CO₃
   • Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
   • Fe + O₂ + H₂O → Fe(OH)₂

   Hint

   Focus on what CO₂ does to calcium hydroxide.

4. 4.

   True or False: Chloride ions enhance the protective oxide layer on steel.

   • True
   • False

   Hint

   Do chlorides help or hurt the protection?

5. 5.

   Given a structure in a coastal area, list five methods to prevent corrosion of reinforcing steel.

   Hint

   Think of how you would protect the metal from clashing with the environment.

6. 6.

   Discuss how you would evaluate existing corrosion in a concrete structure.

   Hint

   Consider both destructive and non-destructive testing.