Passive monitoring of nonlinear relaxation of cracked polymer concrete samples using acoustic emission

This work presents an acoustic emission (AE) monitoring of slow dynamics in micro-cracked polymer concrete (PC) samples. In order to obtain calibrated damage states, AE was first used to characterize the micro-damage mechanisms in real time when PC samples are submitted to three-point bending tests. Then, an unsupervised classification of AE data based on the Principle Component Analysis and the k-means clustering was applied to classify AE data. The AE monitoring of the nonlinear relaxation of PC samples revealed the existence of a silence period followed by AE hits belonging to two different damage classes. A similarity appeared between the properties of the detected AE hits obtained during the nonlinear relaxation and the quasi-static tests. Finally, this work shows that the dynamics of both mechanisms during the nonlinear relaxation are clearly different.