Hydrogen Generated before Ducts are Filled

These observations would attribute the cause of anomalous failure to the presence of an aggressive solution that came into contact with the steel before the ducts were filled with grout A solution with these characteristics is the aqueous phase that is produced in concrete in the first hours following its mixing [1, 9]. 

Today the recommended procedure is to conserve properly the wires or strands before they are utilised, so that localized attack cannot occur make sure before injection that aggressive solutions cannot penetrate the duct inject the mortar immediately after prestressing. 

Protection of prestessing steel. The protection of prestressed tendons from external corrosive agents, in particular from the infiltration of de-icing salts, requires that they are completely surrounded with a protective barrier. 

Temporary or permanent protection of prestressed structures may be necessary. The essential elements to be considered are prestressing steel, the ducts containing the tendons, the anchorage system, the protective system over all. 

As far as the prestressing steel is concerned, corrosion prevention has to be applied from the moment the tendons are delivered until they are embedded. The ducts have to be durable and waterproof, filled with protective materials following the guidelines for correct grouting. 

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