Demonstration of measurements using impulse-radar, ultrasonic echo and impact-echo on a pre-stressed concrete railway bridge in Duisburg / Germany : Sustainable Bridges Background document SB 3.17

Non-destructive test- (NDT-) methods are not yet commonly used for inspection of concrete structures. The automated application of enhanced methods as impulse radar, ultra sonic echo and impact-echo during inspection and condition assessment of existing prestressed concrete bridge structures is tested in this deliverable. These methods were used at a railway bridge in Duisburg/Germany to determine thickness of structures and to localize reinforcementand tendon ducts. The automated tests were performed in October 2005. As results, the tendon ducts in the area of the bridge deck and the web were located using impulse-radar and ultrasonic echo. Advantage of echo-measurement set-up is the accessibility only from one side. The accuracy of the determination of the thickness of the structures or the concrete cover of rebar and tendons depends on the calculation of the wave velocities. Structural elements of known thickness or the radar CMP (Common Mid Point) measurements might be used as references for calibration of the wave velocities. Accurate information about the localisation of tendons was not achieved with impact-echo at this bridge. But investigations have shown that geometry-effects can be reduced by measurements in transmission arrangement.EC Sixth Framework ProgramSustainable Bridges – Assessment for Future Traffic Demands and Longer LivesTIP3-CT-2003-001653</p