Effect of Concrete Strength Level on Acoustic Emission Wave Propagation Characteristics.

The application of acoustic emission (AE) in concrete faces great challenges due to complex material parameters of concrete materials and the rapid attenuation characteristics of acoustic emission wave. In order to clarify the influence of concrete strength level on acoustic emission wave propagation characteristics and create conditions for evaluating concrete damage by acoustic emission technology, the acoustic emission technology was used to study the propagation behavior of acoustic emission waves in concrete with different strength levels through parameter analysis and fast Fourier transform. The results show that the attenuation coefficients of AE energy in C30, C40 and C50 concrete are 0.013 94, 0.010 67 and 0.005 68, respectively, and the higher the strength is, the smaller the attenuation is. The benchmark wave speeds are 3 966 m/s, 4 193 m/s and 4 411 m/s, respectively, and the higher the intensity, the faster the wave speed. The frequency distribution tends to shift from high frequency to low frequency with the increase of propagation distance, but the signal attenuation and frequency deviation of concrete with high strength are slower. The signal wave types received within 500 mm and outside 500 mm are different, which is not conducive to the acoustic emission monitoring. When monitoring the acoustic emission of concrete, the sensor spacing should be within 500 mm to ensure the monitoring accuracy. [ABSTRACT FROM AUTHOR]