Mobile NMR - A powerful tool to measure coating thicknesses in concrete buildings

Abstract

Scores of infrastructural concrete buildings possesses coating systems as protection against aggressive exposure. The functionality of these coating systems is mainly affected by the composition and thickness of there different polymeric layers. A mobile NMR sensor, the so called "NMR-MOUSE®"(Nuclear Magnetic Resonance Mobile Universal Surface Explorer, registered trademark of RWTH Aachen University), enables for the first time ever a nondestructive determination of these controlling parameters. The current results demonstrate the capability of the NMR sensor investigating different coating systems applied on concrete. Analyzing the NMR amplitude as a function of the measuring depth, the composition of the different coating layers gets visible while an accuracy of about 5 to 20 μm can be achieved for the thickness determination. Studying the in fluence of steel reinforcement inside the coated concrete on the NMR signal leads to a correction of the measuring field position in fluenced by concrete cover, steel diameter, amount and position of steel. © RILEM 2013.