Nondestructive measurement of modulus of elasticity of concrete
Concrete as building material underlies in numerous fields of application not only static, but also temporally changing and repeating loads, which can lead over time to material fatigue. Within a research project of the Gesellschaft für Akustikforschung Dresden mbH it was proven that the dynamic modulus of elasticity is a suitable material parameter to draw a conclusion about the status of degradation of road concrete that arises in the course of material fatigue. Therefore, a novel nondestructive measurement method was developed to determine the dynamic elastic modulus of concrete plates in situ. For this, the phase shift method based on the multichannel analysis of surface waves (MASW) was applied to determine the phase velocity of the lamb wave.
The developed method was examplarily applied to a concrete plate of a highway where the modulus of elasticity was determined as a function of frequency and plate depth. Furthermore, four classic procedures, which required to drill core samples from the plate, were used to determine the elastic modulus of the concrete plate as well. Afterwards, the measurement results of all different methods were compared to each other. The results of the novel nondestructive method show a good agreement with the results of the classic measurement procedures. Thus, the developed method constitutes the basis for a nondestructive determination of the elastic modulus of concrete plates in situ.