Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
One-sided access NMR for concrete inspection
In nuclear magnetic resonance (NMR) standard equipment the sensor encloses the specimen, consequently the maximum sample size is restricted and measurements on large specimen require a sampling. Recently, exceptional NMR devices have been developed, which can be applied to the specimen simular to an ultrasound sensor. With this one-sided access (OSA) NMR, a depth profile of the signal can be non-destructively detected inside the component with a resolvable depth of typicall 1 mm. In Hydrogen-NMR ('H-NMR), the measuring parameter spin-density strongly correlates with the moisture contant of a solid material. Therefore, with OSA-NMR the moisture depth profile can be measured in an individual component, masonry, wood, polymers, a.s.o. In concrete structures, penetrating moisture is responsible for most deterioration mechanism. The 'H-NMR spin-mobility is highly sensitive to the physical state of moisture. Using this additional information, also quality affecting properties of concrete, as hydration degree and pore-size distribution can be determined. To apply OSA-NMR as an useful inspection technique on concrete building sites, also operational restraints of conventional equipment, as apparatus, weight, cost and handling, have to be removed. For that reason, it was decided to develop a fully automatic, portable OSA-NMR system for in-field concrete inspection.
One-sided access NMR for concrete inspection
In nuclear magnetic resonance (NMR) standard equipment the sensor encloses the specimen, consequently the maximum sample size is restricted and measurements on large specimen require a sampling. Recently, exceptional NMR devices have been developed, which can be applied to the specimen simular to an ultrasound sensor. With this one-sided access (OSA) NMR, a depth profile of the signal can be non-destructively detected inside the component with a resolvable depth of typicall 1 mm. In Hydrogen-NMR ('H-NMR), the measuring parameter spin-density strongly correlates with the moisture contant of a solid material. Therefore, with OSA-NMR the moisture depth profile can be measured in an individual component, masonry, wood, polymers, a.s.o. In concrete structures, penetrating moisture is responsible for most deterioration mechanism. The 'H-NMR spin-mobility is highly sensitive to the physical state of moisture. Using this additional information, also quality affecting properties of concrete, as hydration degree and pore-size distribution can be determined. To apply OSA-NMR as an useful inspection technique on concrete building sites, also operational restraints of conventional equipment, as apparatus, weight, cost and handling, have to be removed. For that reason, it was decided to develop a fully automatic, portable OSA-NMR system for in-field concrete inspection.
One-sided access NMR for concrete inspection
Kernmagnetische Resonanz für die einseitige Prüfung von Beton
Wolter, B. (Autor:in) / Dobmann, G. (Autor:in) / Herzer, H.R. (Autor:in) / Laub, U. (Autor:in) / Bloem, P.J.C. (Autor:in)
1998
8 Seiten, 6 Bilder, 10 Quellen
Aufsatz (Konferenz)
Englisch