Corrosion Evaluation and Cable Break Detection for Post-Tensioned and Prestressed Cables

Many well documented failures of post-tensioned cables have occurred and the potential seriousness of corrosion induced failures of post-tensioned cables is well recognized and understood. This paper presents two non-destructive means for 1) investigating the probability of corrosion and 2) for locating breaks or section reduction in post-tensioned cables. Also discussed are methods of mitigating the corrosion and extending service life to in-situ post-tensioned cables. The principal cause of corrosion of bonded / grouted or un-bonded / un-grouted high strength post-tensioned cables is due to the presence of moisture (high humidity) and air (oxygen). Moisture infiltration can occur from various sources, including initial construction, leakage, and the nature for cementitious grouting in particular pour quality grouting. Early identification and mitigation of corrosive environments or media can significantly reduce the costs of major repairs and reduce the risk of failure. General principals and basic assumptions of corrosion as it relates to post-tensioned cables will be presented.