Corrosion of anchorage head system of post-tensioned prestressed concrete structures under chloride environment

摘要

Corrosion of anchorage head system may lead to severe structural failure. To understand the characteristics of corrosion and the risks of anchoring failure, 11 post-tensioned prestressed concrete specimens with single-hole anchorage-plate system sealed with postcast concrete contaminated by NaCl were fabricated and then corroded for 8 months. By periodically monitoring corrosion current density and breaking the specimens to detect mass loss, the time-varying law of corrosion rate and the influences of chloride concentration and cover layer depth on corrosion rate were found. The mean corrosion rate of each component of anchorage head system varies with effective prestress level in a light growing trend with approximate linear relationship. The plates were corroded most severely and manifested relatively full and uniform corrosion characteristics, whereas the barrels and wedges were corroded slightly and exhibited relatively local and pitting corrosion characteristics. The average corrosion rate of the plates is 50 times and 80 times higher than that of the barrels and wedges, respectively. The interfaces of the contacted components were hardly corroded. Finally, the corrosion risk of the anchorage head system was analyzed.