Prevention of Corrosion in Post-Tensioned Structures: Electrically Isolated Tendons

Post-tensioning structures with metallic ducts risk corrosion, rupture or collapses due to chloride ingress. The use of tight corrugated polymer ducts combined with electrically isolated anchorages (EIT) changed the situation. Laboratory and many field applications proved the tightness of the duct, showing resistance values higher or much higher than 50 kΩm, the acceptance criteria for a tight duct. The most important fact is that EIT tendons allow quality control and long-term monitoring of the duct tightness. EIT ducts (also with resistance values below the threshold criteria) can be monitored over the whole service life: only a progressive decrease of the measured resistance indicates a corrosion risk for this specific tendon. The most important structural elements can be easily monitored for the first time and damage initiation can be detected early. After a successful use in Europe EIT technology is now expanding progressively in the US.