Combine ingress of chloride and carbonation in marine-exposed concrete under unsaturated environment: A numerical study

Under marine environment, reinforced concrete structures are suffering from serious deterioration problems. The sea water contains abundant contents of ion species including chlorides, and the carbon dioxide exists in the air, which could be exclusively high under industrial-polluted condition. Both the chloride transport and carbonation could happen, intrude through the concrete protection layer and trigger corrosion for the inside rebar. During this process, the mechanism of synergetic work of carbon dioxide, chloride ions and moisture are investigated in the present study. The carbonation process impacts the chloride transport by debounding, while the pore structure will also change, so that the transport characters vary for both. The effects of crucial environmental parameters, the temperature, the relative humidity and the carbon dioxide concentration, on the interaction of carbonation and chloride transport process, are also scrutinized. Considering the existence of liquid in the pore phase, this work principally examined the influence of unsaturated environment on the binary ingress process of chloride and carbonation.