Practical applications of NMR in civil engineering

By studying Hydrogen Nuclear Magnetic Resonance (1H-NMR) signals of water in porous materials, it is possible to determine their properties of water storage and transport. Besides, NMR studies can provide detailed information about the porous microstructure (porosity, pore-size distribution) of these materials. This approach is used in geophysical applications of NMR (e.g. for subsoil investigations), whereas a special NMR instrumentation ("NMR logging" tool) is lowered down into a drilled borehole. OSA NMR is a further type of instrumentation suited for applications outside laboratory environment. Comparable to an ultrasound reflection sensor, it can be applied from one side to the specimen (e.g. a building wall) and provides depth-resolved information about its internal structure (e.g. moisture depth-profile). With this instrumental architecture, NMR is applicable not only for on-site inspection but also for process integrated monitoring (e.g. in wood material fabrication). By determining the water tightness of building structures with OSA NMR, environmental durability problems can be detected in an early stage, preventing unexpected fatal damage due to moisture ingress. A further application is to monitor the drying process in fresh concrete. Moreover, NMR is highly sensitive to the cement hydration degree and the increase of internal surface area of cement-based materials. Hence OSA NMR could used for the non-destructive testing of the early-age strength development in fresh concrete.