Reinforced concrete structures are continuously exposed to the atmospheric environment during service, and carbon dioxide in the air diffuses into the interior through the pores on the concrete surface and undergoes neutralization reactions with alkaline hydration products.
The carbonization front gradually advances deeper into the structure over time.
When the carbonization depth reaches the surface position of the steel reinforcement, the passive film of the steel reinforcement, which was originally in a highly alkaline environment, will lose stability due to the decrease in pH value and undergo electrochemical corrosion in the presence of moisture and oxygen.
Concrete structures such as industrial buildings, underground garages, tunnels, and coastal structures that are exposed to high concentrations of carbon dioxide or high humidity are facing a more severe threat of carbonation.
Due to historical reasons such as low design standards and extensive construction management, some early construction projects have a common phenomenon of carbon degradation, which poses a significant burden on the owner units in terms of structural safety hazards and maintenance and reinforcement costs.
.