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Decrease of the Ultrasonic Pulse Velocity in Concrete Caused by Reinforcement



Author(s)

Uldis Lencis, Aigars Ūdris and Aleksandrs Korjakins

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DOI:10.17265/2161-6213/2011.12.016

Institute of Materials and Structures, Riga Technical University, Azenes 16/20, Riga LV-1658, Latvia

In many countries, the standards issued in the 70s and 80s of the 20th century contain references to reinforcing bars as having impact on the ultrasonic pulse velocity (UPV) propagation in reinforced concrete. The criteria specified in the standards mostly provide for UPV increase in the rebar zones. The presently applied standards, in their turn, contain only recommendations on how UPV measurements should be performed for reinforced concrete, moreover, these recommendations are quite different. Since the times when scientists were focused on the researches in this scope, concrete fillers technology has experienced significant development, improving concrete properties and at the same time changing its structure. The purpose of this research is to evaluate the impact of reinforcing bars on UPV in concrete. Various ultrasonic devices were applied for research to determine longitudinal, transverse and surface wave propagation in concrete by direct and indirect transmission. Measuring in rebar zones and in plain concrete it was established that the obtained results are influenced by specific conditions, which was proved by significant UPV variations and changes given in comparison of the measurement data obtained at various points. The results of present research differ from previously formulated assumptions of UPV increasing in concrete rebar zones.

Concrete, nondestructive testing, ultrasonic pulse velocity, effect of reinforcement.