Acoustic Emission Characteristics during Uniaxial Compressive Loading for Concrete Specimens according to Sand Content Ratio

The acoustic emission (AE) technique has been widely used to monitor damage for concrete structures in underground space. To analyze the damage status successfully, it is important to understand the characteristics of AE parameters during failure for concrete-based-underground structures. The AE parameters are related to the target material characteristics (i.e., sand content ratio) and failure steps (i.e., stress levels) of concrete specimens. In this study, the concrete specimens were prepared with different sand content ratio. Uniaxial compressive tests were performed for the specimens with AE monitoring to investigate the characteristics of AE parameters in the time domain (i.e., count, energy, and amplitude) and frequency domain (i.e., initial frequency and peak frequency). The experimental results were analyzed with the sand content ratio and failure step (1–4) in order to determine the suitable AE parameter as a monitoring index. The most suitable parameter was shown as the cumulative energy parameter of AE with high sensitivity.