TY - CONF A1 - Helmerich, Rosemarie A1 - Milmann, Boris A1 - Wöstmann, Jens A1 - Feistkorn, S. ED - Barros, J. ED - Sena-Cruz, J. T1 - Durability of CFRP-laminate strengthening N2 - First bridge structures have been strengthened by means of Carbon-Fiber-Reinforced-Polymer (CFRP)-laminates extemally glued to the concrete surface in the last two decades. At present there is no Information about the durability of these Systems after having been in Service for more than ten years. The paper presents laboratory tests and case studies with automated non-destructive testing to analyse the current bond condition of extemally bonded CFRP-laminates to concrete structures, strengthened about ten years ago. The paper presents the feasibility and the limitations of ultrasonic inspection of selected areas of CFRP-laminate-strengthened structures co-funded by the German Center of Competence in Civil Engineering (DIBt) in a national project. Areas of interest were the end region of laminates or areas with educated doubts about their bond integrity selected and marked in the inspection records during main inspections. In a feasability study, the functionality of the ultrasonic test for bond evaluation below CFRP-laminates without any surface protection measure, was confirmed by testing a CFRP-laminate strengthened slab with artificial voids in a blind laboratory test with an accuracy of + 1 cm. The accuracy depends on the step width, line interspace and the distance between ultrasonic transducer and receiver. This accuracy suits a measuring grid of 1 cm. The case studies consider flexural strengthening and repair of prestressed concrete structures as well as longitudinal and transverse strengthening of bridge slabs with simple reinforcement. Both alternatives were considered, covered with mineral surface protection layer and without. The measurement results of automated scanned surfaces is presented in color-codes images. In the tested areas with no or thin surface protection the non-destructive inspection did not uncover severe defects or Deterioration processes. None the less, proposals for further research is given, in testing of the acceptable bond defects and in advancing the ultrasonic test including the devlopment of sensors for this application. T2 - FRPRCS-11 - 11th International symposium on fiber reinforced polymer for reinforced concrete structures CY - Guimaraes, Portugal DA - 26.06.2013 KW - CFRP-Laminate KW - Debonding KW - Flexural strengthening KW - Bridge KW - NDT KW - Durability test KW - Inspection PY - 2013 SN - 978-972-8692-84-1 SP - 41 EP - 42 (Session 6.5) AN - OPUS4-28859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -