CORROSION IN PRESTRESSED CONCRETE

摘要

Prestressed concrete structures are prone to corrosion of prestressing strands in aggressive environments; and because these strands operate at a high level of stress their corrosion represents a greater concern because of brittle fracture associated with stress corrosion cracking and hydrogen embrittlernent. Eight prestressed concrete prisms (127×127×2060 mm) with these levels of prestress (0%, 30% and 60%) were subjected to accelerated corrosion by immersion in a 5% NaCl solution and being subjected to a constant voltage. The results of the various electrochemical tests performed during the corrosion period, and visual observations and mass loss test data are reported summarily in this paper. The results of tension tests on the corroded strands recovered from the prisms after the accelerated corrosion tests demonstrated a decrease in both the strand tensile strength and ductility, which should cause concern for strength and ductility which should cause great concern for the safety, serviceability and durability of prestressed concrete structures. Assessment of all of the data showed that there was no correlation between the level of initial prestress and the corrosion activity. More research is needed in this area to mitigate or at least minimize the risk of corrosion in prestressing strands in corrosive environments, and to construct and maintain prestressed concrete structures to ensure their durability.