A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Contribution of capacitance probes for nondestructive inspection of external post-tensioned ducts
Evaluating the actual state of civil engineering infrastructures is a priority for their administrators, knowing the high cost of the construction compared to that of maintenance. For post-tensioned concrete bridges with internally grouted tendons, there was a lack of tools able of revealing the presence of grout voids and high moisture content regions resulting in most of the common pathologies. In this context, the capacitance method appears as a powerful non-destructive approach, and the device proved efficient to find grout injection defects; Information about an elementary tendon failure or substantial cable corrosion analysis should be also potentially achievable in the same way. Indeed, in spite of a small penetration depth, this method can be fully exploited in complex situations involving a combination of conductive and resistive materials, where no other system is usable. Furthermore, it is possible to adjust the investigation volume, by varying both the arrangement and geometry of the electrodes. This point is still subject to researches, in particular to prevent erroneous measurements due to fringing effects, or to improve the axial evenness by adding appropriate guard rings (Yang et al., 1999). The applications of this atypical technique have remained marginal in the field of civil engineering, because of the difficulties for interpreting the measurements. Furthermore, the behavior of the sensor may be disturbed by a variety of factors, for instance the presence of thin air layers inside the duct (because of grout shrinking when drying), frequency dispersion, phenomenon of interfacial polarization of the electrodes, imperfect contacts with the duct envelope, etc. These points are now being considered from a physical modeling point of view, and we can expect technical advances (via the implementation of array sensors, as an example) as well as an evolution of the data-processing.
Contribution of capacitance probes for nondestructive inspection of external post-tensioned ducts
Evaluating the actual state of civil engineering infrastructures is a priority for their administrators, knowing the high cost of the construction compared to that of maintenance. For post-tensioned concrete bridges with internally grouted tendons, there was a lack of tools able of revealing the presence of grout voids and high moisture content regions resulting in most of the common pathologies. In this context, the capacitance method appears as a powerful non-destructive approach, and the device proved efficient to find grout injection defects; Information about an elementary tendon failure or substantial cable corrosion analysis should be also potentially achievable in the same way. Indeed, in spite of a small penetration depth, this method can be fully exploited in complex situations involving a combination of conductive and resistive materials, where no other system is usable. Furthermore, it is possible to adjust the investigation volume, by varying both the arrangement and geometry of the electrodes. This point is still subject to researches, in particular to prevent erroneous measurements due to fringing effects, or to improve the axial evenness by adding appropriate guard rings (Yang et al., 1999). The applications of this atypical technique have remained marginal in the field of civil engineering, because of the difficulties for interpreting the measurements. Furthermore, the behavior of the sensor may be disturbed by a variety of factors, for instance the presence of thin air layers inside the duct (because of grout shrinking when drying), frequency dispersion, phenomenon of interfacial polarization of the electrodes, imperfect contacts with the duct envelope, etc. These points are now being considered from a physical modeling point of view, and we can expect technical advances (via the implementation of array sensors, as an example) as well as an evolution of the data-processing.
Contribution of capacitance probes for nondestructive inspection of external post-tensioned ducts
Ensatz von Kapazitätssonden zur zerstörungsfreien Untersuchung externer nachgespannter Kanäle
Iaquinta, J. (author)
2004
9 Seiten, 8 Bilder, 25 Quellen
(Nicht paginiert)
Conference paper
Storage medium
English
Capacitive probe for non destructive inspection of external post-tensioned ducts
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