The determination of prestressed concrete covering layer system depth under atmosphere condition

The prestressed concrete covering layer system, different with the general reinforced concrete cover, is a complex system which includes not only the non-uniform layer of concrete, but also the non-prestressed reinforcement, the metal corrugated pipe and the cement paste incrustation body in the pipe. Therefore, the study for carbonization corrosion of the prestressed concrete structures should consider effect of the stress and deactivated film position of reinforcing bar. Taking into consideration of the effect of stress level in concrete diffusion process, the carbonization reaction and diffusion process in the complete carbonated zone and the half-carbonated one under multi factor is analysed. It presents the durability limit state equation for prestressed concrete structures under carbonization condition, which can determine the depth of the covering layer system for prestressed concrete structures.