Chloride damage concrete

Chloride damage affects concrete structures from within. It occurs when chlorides – substances found in seawater, de-icing salt, and certain chemicals – come into contact with the reinforcing steel in concrete. These chlorides react with the steel, causing it to rust. This leads to expansion of the steel, which in turn causes cracks in the concrete. In other words: chloride damage occurs in the concrete. It is also referred to as concrete rot or carbonation of concrete.

What are the Consequences of Chloride Damage to Concrete?

The consequences of chloride attack are not only visible on the exterior but also very dangerous. Below, we delve deeper into all the consequences of chloride damage to concrete.

Weakening of the Structure

Chloride ions attack the reinforcing steel, making the concrete brittle and porous. This results in cracks, powdering, and crumbling of the concrete surface. The corrosion of the reinforcing steel also reduces the load-bearing capacity of the structure, leading to crack formation, deformation, and possibly even collapse.

Economic Burdens

Repairing concrete structures affected by chloride is complex and expensive. Regular inspections, repair work, and possible renovation are necessary to ensure safety.

Chloride damage makes concrete structures less usable for a shorter period, requiring earlier replacement or repair, which incurs additional costs. Buildings and roads with this damage also lose significant value, making them more difficult to sell or finance.

Environmental Effects

The corrosion of reinforcing steel releases harmful substances, such as salts and metals, which pollute water and damage nature. Concrete production also requires a lot of energy, leading to waste and increased CO₂ in the air when we replace damaged concrete structures.

Societal Impact

Chloride damage can eventually cause serious accidents, such as collapses of buildings and bridges. This can result in injuries or even fatalities. People may also lose confidence in the safety of buildings and roads if such accidents occur.

The quality of the concrete plays an important role in preventing chloride damage. In addition to using reinforcement as a defense mechanism, concrete also has its own protective measure: the chloride class, also known as the environmental class. This class indicates how well concrete can withstand attack by chlorides, substances found in seawater, de-icing salts, and certain chemicals.

Why is the Chloride Class Important?

Choosing the right chloride class is important when designing and constructing concrete structures, especially in areas where the risk of chloride attack is high. By taking into account the expected chloride load, we can select concrete that is optimally resistant to these harmful substances.

Read more about the environmental classes of concrete here.