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Concrete Rot: Risks and Prevention

Concrete structures face significant threats from carbonation and chloride penetration, both of which can lead to severe reinforcement corrosion and structural damage. Understanding these processes and taking proactive steps, such as regular inspections, can safeguard your property from costly damage and ensure the longevity of your investment.

There are 2 types of concrete rot

  • Carbonation (PH of the concrete drops below 9 PH, it becomes more acidic)
  • Chloride (chloride-initiated reinforcement corrosion)

We also see damage in the form of:

  • Mechanical damage (damage due to drilling, chopping or laying on, etc.)
  • Low concrete cover (reinforcement in the concrete surface)
carbonatatie.png

Concrete damage due to carbonation

In civil engineering, carbonation occurs naturally in concrete. During the hardening of the concrete, calcium hydroxide (from cement) is formed, which reacts with atmospheric carbon dioxide. Calcium hydroxide creates the alkaline environment in the concrete, thus protecting the reinforcement.

The carbonation reaction eventually causes the pH value to drop below 8 to 9, which makes corrosion of the reinforcement (concrete rot) possible.

Carbonation occurs over the entire concrete surface, so if damage occurs, we can assume that the process manifests itself over the entire surface.

voorbeeld-carbonatatie.png

Concrete damage due to chloride

Chloride can occur in concrete as a result of:

  • Addition in the form of calcium chloride to accelerate hardening.
  • Penetration of chloride by de-icing salts, seawater, etc.

When the chloride content is above the critical limit (>0.4 mass% based on the cement weight), there is a risk of chloride-initiated reinforcement corrosion.

  • Calcium chloride causes pitting corrosion
  • In some places a reinforcing bar can rust completely through.
chloride.png
voorbeeld-chloride.png
putcorrosie-door-chloride.png

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