Carbonation depth refers to the extent to which carbon dioxide from the atmosphere has penetrated into concrete and reacted with the hydrated cement components to form calcium carbonate. This natural process is critical in the life cycle of concrete as it influences both the material’s durability and its ability to protect embedded steel reinforcement from corrosion. Understanding carbonation depth is essential for assessing the long-term performance and integrity of concrete structures, particularly in urban and industrial environments where CO 2 concentrations are elevated.