Abstract
The structure and placement of unbonded post stressed tendons is discussed briefly, together with regard to possible problems relating to ingress of water between the outer polyethylene sheath and inner stressed steel strand. Premature corrosion and failure of some tendons after fourteen years service in a floor slab are examined via optical and scanning electron microscopy (SEM) and related to conditions occurring within the tendons. Water penetration caused localized crevice corrosion of individual wires in the strand via formation of oxygen concentration cells, consistent with in-situ pH measurements of the water environment in the tendon. Initially, such corrosion propagated as cracks transverse to the axis of the individual wires. Subsequent hydrolysis reactions within the crevices/cracks produced local pH conditions conducive to hydrogen embrittlement and crack propagation along the wire axis, consistent with cracking observed under hydrogen charging conditions.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
