Practical applications of NMR in civil engineering: Fid-Bau Portal

Practical applications of NMR in civil engineering

Wolter, B. / Kohl, F. / Surkowa, N. / Dobmann, G.

For a long time, nuclear magnetic resonance (NMR) instrumentation was found only in laboratories of institutional and industrial research facilities. Nowadays, special NMR equipment is available, which can be lowered down to a borehole in order to characterize water and oil deposits or which is one-sided (OSA) accessible to the specimen in order to inspect the moisture situation in a building wall or. NMR-INSECT - developed at the IZFP - is portable, robust and easy-to-use device which is based on this OSA NMR approach. It combines the large potential of NMR with an instrumental design, fulfilling the requirements of non-destructive testing on building-sites. The experimental results have shown, that OSA NMR is a powerful tool for determining a variety of water related properties of mineral construction materials and soils. Spatially resolved measurements of the water content provide an unique possibility to characterize drying and wetting processes in building materials and with it to recognize the risk for a reduced residual life time at very early times - a clear progress in the light of structural safety. NMR relaxation measurements could help to accurately control concrete work (production and mixing) as well as to monitor workability and strength development after setting. For the first time, it is possible to accurately determine the time for demolding or removal of formwork in-situ. Further applications arise from the identification of early stiffening and flash set in ready-mix suppliers.