## 3 Results and Discussion
### Time-Series Analysis  
The comprehensive concrete fracture behavior is described by the AE and DICM parameters from time-series data (Figure 13).  
Figure 13: AE and DICM time-series data: (**a**) sample No. 5; (**b**) sample No. 8; (**c**) sample No. 9; (**d**) sample No. 11; (**e**) sample No. 12.  
The vertical left axis of the graph corresponds to the major principal strain measured by DIC, and the vertical right axis is the AE energy release rate. The comparison of both parameters is shown on the strain energy level. The major principal strain was extracted in the nine locations on the horizontal line in the central sample's part during the entire compression loading (Figure 5b). As can be seen from Figure 13, each sample has a unique deformation trend depending on the specific pre-existing fracture distribution. Moreover, there is a relationship between AE energy release activity and deformation. As both AE and DICM are non-destructive techniques allowing the monitoring and visualization of the interior and exterior damage evolution in the material, the early fracture processes and their development can be detected by the high AE energy release and strain concentration in the area of the material. Therefore, a precise analysis of fracture behavior can be conducted based on these results. Using time-series analysis, the relationship between both parameters can be visible. Sample No 5 (Figure 13a) showed the sudden AE emission of high intensity at the strain energy level of 40%, where the strain concentration can be distinguished at the same level. The most contributed part is the right sample part, where the main fracture can be concluded. Sample No. 11 (Figure 13d) also illustrated the clear deformation process starting at 20% of the strain energy level. However, the main AE activity can be found at the 40% of strain energy level, which can be due to the defects distribution within the concrete matrix: small energy for crack development released that can be the evidence of severe conditions of pre-existing defects system. The slope change can be seen at the 40% strain energy level, which means the rate of fracture development is increasing. Both these samples demonstrate the obviously dominated zone of deformation, which is correlated with pre-existing defects. In addition, the sudden slope change can be seen at 100% of the strain energy level, which depicts the final stage of sample failure. Sample No. 8 demonstrates the earlier deformation behavior at the initial loading stage corresponding to the popping out of the coarse aggregate on the upside of the sample. The slope also changed after the high AE energy release (40% strain energy level) and continued until final failure with deformation domination on the right sample side. Samples No. 9 and No. 12 (Figure 13c,e) show the continuous strain concentration in the whole central part that is correlated with the pre-existing defect system distribution. The same slope-changing phenomena can be mentioned after a significant AE energy release event as in the previous samples.  
According to time-series results, the correlation between AE and DICM parameters can be attributed to the intense AE emission and strain concentration. Both these aspects indicate the occurrence and localization of fracture activity, the presence of defects within the concrete matrix, the severity of pre-existing defect systems and the initiation and development of fractures. The changes in slope after significant AE energy release events suggest changes in fracture mechanisms, accelerated fracture development rates and the propagation of fractures leading to further deformation and eventual failure. The combination of AE and DICM data provides a comprehensive understanding of concrete fracture behavior and enables a precise analysis of fracture processes and their correlation with pre-existing defects.