Early identification and mitigation of corrosive conditions can significantly reduce the costs of major repairs and the risk of structural failure. The principal cause of corrosion of unbonded post-tensioned cables is the presence of moisture and air inside voids along the cable sheaths. Moisture infiltration can occur from numerous sources including initial construction, ground water, roof leakage, and poor quality grout pockets.
Post-tensioned cable corrosion occurs most often in unprotected structures such as parking garages, balconies and roof slabs; however numerous instances of cable wetness, cable corrosion and cable failure have been recorded at interior protected buildings. Left unattended this corrosion can lead to cable failure, serious cable eruptions from concrete floors and costly cable repair and replacement.
Until recently, methods of non-destructive testing and evaluation were limited. Vector’s Post-Tech® Corrosion Evaluation and Cable Break Detection system are available to access the condition of post-tensioned structures. These systems can assist engineers and building owners in the assessment of overall cable conditions to formulate cost effective repair and preventative maintenance alternatives. When compared to conventional means of evaluation, structural reinforcement or cable replacement, significant cost savings can be achieved.
Post-tensioned corrosion can be mitigated using Post-tech Cable Drying and Grease Injection. Exposed steel such as anchorages can be protected galvanically with systems such as Galvashield® XP and CC embedded galvanic anodes as well as surface mounted Galvanode® ZincSheet.