Acoustic Emission Test and Damage Fractal Characteristics Analysis of Concrete with Different Initial Porosity

In order to explore the relationship between the acoustic emission (AE) signal's characteristic parameters and the damage evolution of concrete, the acoustic emission test on concrete specimens with different initial porosities under uniaxial cyclic loading conditions. The activity coefficient was introduced to express the activity level of acoustic emission. A method of evaluating concrete working state based on acoustic emission energy was put forward. Fractal dimension theory was used to analyze the acoustic emission energy sequence evolution characteristics of concrete with different initial porosities. The results showed that the correlation dimension of acoustic emission energy and acoustic emission energy of concrete blocks with different initial porosities was basically the same as that in the loading process, and the critical position of instability failure was equivalent. The concrete damage could be predicted when the peak of acoustic emission energy dropped again, the average energy was more than 100 m V·ms and the activity coefficient slowed down continuously within the 20~70 range. The acoustic emission energy correlation dimension decreased continuously and showed a horizontal trend signaling the ultimate bearing capacity of concrete structure.