Cooling towers and chimneys can be subject to different types of environments causing corrosion and damage.
1. Damage due to concrete defects or attack
- Aggressive exhaust gas
- Condensation leaking
- Thermal movement cracking
- Adverse thermal gradient cracking
- Freeze/thaw action
- Shrinkages (from hydration)
2. Damage Due to Steel Reinforcement Corrosion
- Atmospheric carbon dioxide ingress (loss of alkaline protection).
- Carbon dioxide from the atmosphere penetrates progressively into the concrete and reacts with the calcium hydroxide in the pore liquid.
- This eventually reduces the protective alkalinity around the steel, allowing corrosion to start in presence of water.
- This phenomenon is often associates with low concrete cover.
Chlorides and Acid Gases
In these structures corrosion of the reinforcement can also occur due to attack from chlorides in marine atmosphere. However, the steel is far more frequently attacked directly by the acidic exhaust gases in conjunction with carbonation of the surrounding concrete. This means that the steel corrosion is accelerated and spalling, plus erosion increases.