Non-destructive testing and evaluation of adhesion and surfaces (VSS2006/514_OBF)
Overview
Background & policy context:
Applied on concrete bridges, non-destructive testing like ground penetration radar and thermography obviously provide useful information for the evaluation of the total structure consisting of sealing systems and bituminous layers. Since the collection of drill core samples provide local information only, large areas can be tested continuously with the above mentioned methods. In addition, sampling of drill cores always leaves damages.
Basically every avoided drill work on bridges is a good sampling. Destruction free testing methods enable the renouncement or at least reduction of sampling drill cores. First experiences in this field already exist. Nevertheless, there is no systematic adjustment of testing methods relative to normative systems in Switzerland that provide guidelines for their standardization.
Objectives:
To improve the application of non-destructive testing in order to avoid damages on tested objects, as well as to reduce the number of samples is the main objective of this project. The project should:
- determine the detection limit in observing damages (extent and size) like e. g. constructional defects in concrete, damages in bituminous layers, insufficient connectivity between layers etc.
- determine the detection limit of humidity in concrete and adhesion mediators
- determine the detection limit of insufficient connectivity (lacking versus insufficient connectivity, extent of damage)
- discuss obtained results about the surface structure
- discuss influences of determined damages on sealing systems
- evaluate the suitability of applied destruction free testing methods
- recommend a range of application for the ZFP testing methods
- propose requirement values on the basis of obtained testing results and analysis of available data
Methodology:
Methods used
The power of non-destructive testing methods to assess (ZFP), the comparison with other test methods is essential. Here are examples:
Humidity: thermography / CM measurement, isotopic probe
Porosity: thermography / Torrent, determination of porosity on core
Texture: Laser / sandy spot
Open GPR / leaf rake / window: defects / voids
Further ZFP methods are:
- IR spectral analysis (detection of water and other substances harmful)
- Ultrasound (detection of defects / cavities)
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