Acoustic emission characteristics of concrete and its constituent materials under uniaxial failure

To investigate the relationship between concrete and its constituent materials in the acoustic emission characteristics of the damage, uniaxial compression tests of concrete, cement mortar and limestone were carried out, and the acoustic emission signals during the failure process of the three were collected simultaneously. The mechanical properties, acoustic emission energy spectrum, amplitude, frequency, peak frequency and acoustic emission b-value of the three materials were statistically analyzed. The results show that the peak frequency and amplitude of the acoustic emission signals from all three specimens increase at the time of imminent damage. The frequency distribution of all three shows a normal distribution, with the largest proportion in the 90-120 kHz range. The dynamic b-value trends for cement mortar and concrete do not fluctuate much and remain in a relatively high value range, the dynamic b-value of limestone shows a trend of increasing first and then decreasing, and decreases rapidly near the peak stress, indicating the coming of main fracture. The overall b-value and peak frequency distribution of concrete are between limestone and cement mortar, the overall b-value of cement mortar mixed with limestone is close to that of concrete, this reflects the superposition effect of acoustic emission characteristics of the failure of concrete and its constituent materials.