Carbonation-induced corrosion damage and structural safety for concrete structures under enhanced greenhouse conditions

The research report will assess how predicted increases in atmospheric CO₂ levels will affect carbonation-induced corrosion damage and safety loss to RC structures, and carbonationinduced safety loss to PSC structures. Probabilistic methods are used as there is significant uncertainty and variability of atmospheric CO₂ levels, deterioration mechanisms, material properties, dimensions and loading. The time-dependent structural reliability analysis will predict the probability of corrosion initiation, the mean proportion of corrosion (cover) damage, the probabilities of flexural and shear failure of typical RC beams, and the probability of failure (collapse) of a typical prestressed concrete AASHTO bridge girder over the next 100 years considering IPCC future atmospheric CO₂ emission scenario predictions. For RC and PSC structures, for the worst case emissions scenario the mean proportion of corrosion damage is up to 540% higher than that predicted for the best CO₂ emission mitigation scenario. There is thus a significant likelihood of corrosion damage that will need costly and disruptive repairs during the service life of many concrete structures. For the worst case scenario the probabilities of flexural and shear failure are about 6% and 18% higher than the best mitigation scenario, respectively. If the worst emissions scenario is viewed as the most likely scenario, and existing design cover is less than 50-60 mm, then increasing design cover by approximately 3-18 mm may be needed to ameliorate corrosion damage over the next 100 years.