Influence of concrete age on the behavior of ultrasonic waves in interfaces (concrete–steel–concrete)

This paper presents the influence of the composite age on the variation of the transmission and reflection coefficients. The composite is the concrete in our case. The studied structure is a multilayer structure composed of two elastic and isotropic layers where each one is characterized by its own physical properties. The problem is simplified in two-dimensional plane waves, and the influence of the attack angle on the acoustic impedances is also examined. Moreover, an experimental study is realized in the formulation of concrete and the measurement of waves propagation velocity. In this work, during the concrete formulation, three different types of concrete were developed: sand concrete, ordinary concrete, and high-performance concrete. The results of simulation and experiments demonstrate that the age of concrete and the internal concrete structure have a direct influence on the evolution of the acoustic parameters as well as the angle of incidence, which has considerably changed the behavior of the transmission and reflection coefficients. This internal structure is directly related to the age of the concrete where its maturity is not reached until after a certain age, which influences the behavior of the waves through the layers of the multilayer structure.