Nondestructive characterization of fresh concrete and other porous materials with one-sided access NMR

Hydrogen nuclear magnetic resonance (1H-NMR) is a direct method to determine the hydrogen content and with it the water content (moisture) in solids. Simultaneous 1H-NMR allows to characterize structure molecular dynamics in hydrogenous liquids as well as in hydrogenous solids. In the past the capability of NMR for characterizing structural properties in porous media has been investigated extensively. Today, NMR instrumentation is found not only in laboratories of institutional and industrial research facilities anymore. Since several years, special NMR devices based on the one-sided access (OSA) NMR approach are available. In several research projects it was demonstrated, that OSA-NMR allows to transfer pure laboratory investigations to the nondestructive inspection of components. The range of applications includes the depth-resolved determination of moisture profiles during wetting and drying of concrete, the investigation of specific surface and restricted diffusion in stones and the observation of cement hydration during concrete hardening. Despite its wide potential for building material characterization, OSA-NMR has not evolved to a routinely used inspection tool due to the high equipment costs and the limited inspection depth.