Evaluation of carbonation progress of existing concrete structure based on air permeability of concrete cover - A case study in Japan

This paper deals with the on-site air-permeability of concrete cover and its relation to carbonation progress of existing RC structures in Japan. The air permeability of concretes and carbonation progresses were measured with 4 buildings and 11 concrete specimens which ages ranged from 12 to 45 years. The carbonation velocity (A) based on the square root theory increases with the increase of air permeability coefficient (kT). Although the relationship between A and kT for all building and concrete specimens has quite large scatter, the relationships between them for individual buildings were comparatively good. This might provide a good perspective for indicate that evaluation of carbonation progress based on the kT should be performed at each building, i.e. environmental condition.