Effect of propagation distance on acoustic emission fracture mode classification in textile reinforced cement

Textile reinforced cement (TRC) is a composite material being increasingly used for load bearing applications. Damage in TRC as in all cementitious materials is an important issue in civil engineering. Acoustic emission (AE) exhibits promising outcomes in laboratory and in in-situ monitoring applications. Evaluation of the fracture mode is crucial as generally, shearing phenomena occur later than tensile (bending) cracking and indicate more severe damage. The acoustic signatures of the damage modes influence most of AE parameters including the average frequency AF and RA-value. However, there are no universal classification boundaries between tensile and shear signals mainly due to geometric effects, material properties, as well as sensor location and response function. In order to highlight this problem and discuss the possibility of a solution, the study occupies not only with the evaluation of the damage mode based on AE parameters but in addition uses multiple sensors to investigate the effect of the wave propagation distance. This is crucial in thin cementitious laminates since damping, scattering, reflections and plate wave dispersion seriously distort the signal having a strong effect on the classification result. It is seen that the classification boundaries between tensile and shear fracture should incorporate the information of propagation distance.