A Fundamental Study to Use Ultrasonic Shear Wave for Quality Control of Concrete

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In this study, we investigated the properties of concrete by means of travelling ultrasonic pulsed shear wave. The results are summarized as follows.1. Application for testing method for time of settingThe setting time is defined by the characteristics of the dynamic shear modulus-elapsed time curve. It becumes clear that the setting time, varied with water-cement ratio of the mixture, temperature, admixture, and so on, has a significant meaning for exection schedule of concrete work.2. The characteristics of the ultrasonic shear wave travelled through concreteThe power spectrum of the response function of concrete in the early age is limited in the lower frequency range, and the peak frequency dose not agree with that of the operated frequency. It is found that the phenomena is caused by the characteristics of attenuation coefficient of concrete. That is the curves of attenuation coefficient versus frequency have a minimum at each age, and the point shifts to higher frequency with age.3. Application for non-destructive testing methods of concreteIt is found that the compressive strengh of concrete is estimated accurately by it's dynamic shear modulus of cement paste which is calculated by applicating the theory of elasticity of two phase systems The advantage of this method is that compressive strength of concrete is determined independently of mix or age.