Ultrasonic NDT Prototype for the Inspection of Ducted Post Stressing Tendons in Concrete Beams

There is worldwide concern about concrete bridges which derive their strength from post stressed steel tendons in grouted ducts. Problems arise when grouting has not been carried out properly, since the combination of voided regions and moisture penetration can cause corrosion of the tendon and catastrophic failure of the structure [1]. Post tensioned bridges built during the middle of this century are particularly susceptible and there is a pressing need for a cost effective non destructive means of assessing the condition of the embedded ducts and tendons. In response to this problem, a track mounted ultrasonic scanning system ‘CANDI’ (Cable Analysis by Non Destructive Inspection) is currently under development in UMIST, and this work describes the CANDI prototype and results obtained

DGZfP Merkblatt B11 \u2013 A Guideline Describing Fundamentals and Applications of the Impact-Echo Method

The Merkblatt (guideline) B11 describes the present state of technology of the impactecho method as it is currently acknowledged in Germany. It contains an explanation of the scientific-technical bases, a description of the method and instrumentation, and an overview of application possibilities, which are illustrated by sample applications. Further sections treat test reports and personnel qualification. A bibliography is also included. The guideline gives necessary information and decision bases for applications in the field and in the laboratory. It is meant to offer a common basis to clients and contractors for the communication over the possibilities, employment requirements, and limits of the method. Work on the guideline is currently being finalized. It will be issued by the Deutsche Gesellschaft f\ufcr Zerst\uf6rungsfreie Pr\ufcfung (DGZfP), Berlin. This contribution gives an overview of its contents including selected special topics and application examples