Several non-destructive techniques are available to measure the damage of concrete structures subjected to loading, including ultrasonic wave propagation. Generally, in concrete ultrasonic studies, primary waves (P-wave) are mostly used for faster speed and higher penetration depth. Under loading, concrete…
Several non-destructive techniques are available to measure the damage of concrete structures subjected to loading, including ultrasonic wave propagation. Generally, in concrete ultrasonic studies, primary waves (P-wave) are mostly used for faster speed and higher penetration depth. Under loading, concrete undergoes micro and macro cracking. The second and third harmonic ratio methods are used extensively in P-wave studies to assess the initial micro-cracks in concrete. In this present investigation, the second and third harmonic ratios are measured by using shear wave (S-wave) to assess the initial damage in concrete. Using shear waves in concrete offers the advantage of minimising backscattering and signal attenuation along the direction parallel to the wave propagation. To study the effect of water-to-cement (w/c) ratio on nonlinear parameters, three w/c ratios, viz, 0.35, 0.45, and 0.55 were chosen. The cracks were induced in concrete by applying compressive loading in a 150 mm cube specimen at a loading increment of 100 kN until failure of the specimen. The experimental results obtained from the S-waves were utilised to investigate the nonlinear parameters β and γ concerning micro and macro damage in concrete with respect to harmonic ratios.