Evaluation of corrosion rate of post tensioned tendons in prestressed concrete structures

Prestressing by post tensioned tendons is widely used to build bridges and viaducts due to the opportunity for greater design choices offered by the construction technology. The corrosion protection of wires or strands inserted inside metal or polymeric sheaths is entrusted to injection mortar. Grouting defects often lead to the triggering of corrosive phenomena. The presence of a metal duct and the difficulty of accessing the steel wires or strands considerably reduces the possibility of using the standard procedures commonly adopted for the evaluation of the corrosion rate in ordinary reinforced concrete structures Of particular interest the problems related to environments completely saturated with water in the total absence of grouting mortar. The preliminary results of some investigations aimed at using the combined use of analytical investigations and electrochemical measurements are reported here and aimed to obtain an estimate of tendon ultimate limit state conditions.