Using compression wave ultrasonic transducers to measure the velocity of surface waves and hence determine dynamic modulus of elasticity for concrete

摘要

A new method of measuring the velocity of surface waves and hence determining the dynamic modulus of elasticity and Poisson's ratio for concrete or other solid materials is presented. When a pair of conventional compression wave ultrasonic transducers are placed on the surface of a solid, surface (Rayleigh) waves will be generated and propagate along that surface. Due to the marked difference between the amplitude of compression waves and surface waves, the leading edge of the surface waves can be identified on the waveform and their arrival time can be measured. Using the relationship between the dynamic modulus of elasticity, Poisson's ratio and the velocity of surface and compression waves, the dynamic modulus of elasticity and Poisson's ratio can be calculated. In the research project described in this paper, concrete specimens were made to permit measurement of dynamic modulus of elasticity and Poisson's ratio using the proposed method and results were compared with values obtained by the conventional resonance method. These experimental results show that the proposed new method is reliable. Because specimens of specific shape and size are not required, the dynamic modulus of elasticity can be measured directly on in situ construction using this approach.