P-wave arrival determination and AE characterization of concrete

The arrival time of the first P-wave is, among other parameters, of prime i mportance for pinpointing the location of an acoustic emission (AE) event s ource. However, it seems that determining the first P-wave arrival times fr om digitized signals has been overlooked in previous works. In this paper, a new method is proposed based on digital signal processing techniques. AE analyses are then performed for both normal-strength concrete and high-stre ngth concrete in uniaxial tension to study the damage initiation and progre ssion by interpreting the activities and locations of AE events. The result s indicate that using the proposed method to determine the P-wave arrival t ime of AE signals is quite successful. It is found that microcracking, star ts early before peak stress. Localization is clearly observed for both norm al-strength concrete and high-strength concrete. The examination of AE acti vities and source location maps reveal that the internal microcracking beha vior is consistent with the macroscopic deformation behavior of the materia ls.