Elastic waves emitted by microfracturing are called acoustic emission (AE). Recently AE techniques have been extensively applied to concrete engineering as a non–destructive testing (NDT) method. A key aspect of AE is that the nucleation of internal cracks is directly detected by a surface observation. In conventional AE techniques, such AE parameters as event count (activity), amplitude, energy and spectra are correlated with the failure process of materials. Thus, AE characteristics are utilized for NDT. The AE source (crack) is also located by employing a multichannel (more than 5) AE detecting and recording system. In this Paper an advanced AE analysis procedure is proposed. In addition to crack locations, crack types and crack orientations are determined from AE relative amplitudes of the first motions. The procedure classifies cracks into tensile cracks and shear cracks. Based on information of the crack type, the crack orientation is determined; this is the direction of crack opening in the case of...