Reliability of the grouting of tendons under consideration of uncertainties under on-site conditions

This paper contributes to the body of knowledge from German research work Deutscher Ausschuss für Stahlbeton and from author’s experiences, to improve the reliability of cable ducts grouting. The complete and reliable filling of post-tensioned tendons with grout is necessary to protect the prestressing steel against corrosion and for bond between prestressing steel and the concrete structure, which is in both limit states applied. Diagnostics of bridges built in the last century showed the cases of faulty grouting of cable ducts. These faults are cause of corrosion prestressing steel often. Based on these diagnostics, bridges are after 35 to 70 years of service life demolished, although service life of these bridges was to 100 years declared. In the studied research work were investigated the effects of individual components, procedures and conditions of the grout and results of grouting investigated. Tests have been performed both on the experiment cable ducts and the real structures. Based on this paper, certain principles have been recommended that aim to prevent grouting faults and to improve the reliability of the grouting. In these recommendations are suggestions of controls of grouting included.