What is the effect of carbonization on reinforced concrete?

Carbonization in reinforced concrete primarily refers to the reaction of carbon dioxide in the atmosphere with the calcium hydroxide in the concrete, leading to the formation of calcium carbonate. This chemical process lowers the pH of the pore water in the concrete. Since the passivation layer surrounding steel reinforcement relies on a highly alkaline environment to protect it from corrosion, a reduction in pH due to carbonization can compromise this protective layer. As a result, the exposed steel reinforcement becomes susceptible to corrosion, which can significantly reduce the durability and structural integrity of the concrete element over time.

This makes understanding the effects of carbonization crucial for engineers and construction professionals, as it informs maintenance practices and the long-term performance of reinforced concrete structures. In contrast, the other choices do not accurately describe the impact of carbonization on reinforced concrete.