Measurement of Acoustoelastic Coefficients in Concrete Using Thermal Modulation of Ultrasonic Waves

This study develops a new method to determine the acoustoelastic coefficient in concrete using thermally-induced ultrasonic bulk wave velocity changes. This paper presents the equations of wave velocity changes caused by homogeneous temperature variation and uniaxial strain in an isotropic medium. The acoustoelastic coefficient of a concrete sample was calculated using the third-order elastic constants (l, m and n) which were determined in the thermal modulation test. The acoustoelastic coefficient of the same sample was then experimentally verified in a four-point bending test. The results showed that relative wave velocity change predicted by the third-order elastic constants from the thermal modulation test agreed well with the experimental value from the bending test.