# Fracture Evolution and Mechanical Properties of Mortar Containing Different Inclusions
## 5 Conclusions  
In this study, mortar samples with different cylindrical inclusions were tested under a uniaxial compression load to study the effect of inclusions on fracture evolution and mechanical properties of mortar structures with the application of the DIC method. The measurement circle method was proposed to further explore the evolution of fractures. The following conclusions can be drawn based on this paper:  
1. The existence of inclusions can significantly improve the stress concentration around the opening and increase the strength of the mortar sample. However, this improve  
Figure 15: Evolution characteristics of the maximum principal strain at monitoring points on a crack path.  
ment in overall strength is not very obvious when the inclusion is stronger than the external material.
2. The inclusion has a significant influence on the fracture pattern of the sample. When the inclusion is weaker than the external material, the inside of the inclusion will undergo penetrated tensile failure along the loading direction. The failure mode of the external part is similar to the samples without an inclusion. The top and the bottom of the opening are characterized by tensile failure, but the splitting failure around the left boundary of the opening is not apparent due to the restraint effect of the inclusion. The debonding failure along the interface is not conspicuous either. When the mechanical properties of the inclusion are consistent with the external material, the debonding failure can be found. Under the influence of the interface, the presence of failure within the inclusion is unlikely to lead to contiguous deformation or a pronounced failure that extends through to the external material.
3. The results of the strain evolution of the measurement circle along the fracture path show that, under uniaxial static compression, the fracture's propagation can be divided into four stages: the quiet stage, the formation stage of the stress concentration area, the stable crack propagation stage, and the rapid crack propagation stage.
4. The strength of the intact sample is higher than that of all samples containing inclusions, even if the inclusions are identical or stronger than the external material. This shows that the discontinuity of the mechanical properties of the inclusions and the external material may have a certain weakening effect on the overall mechanical properties of the sample, which suggests more attention should be given to the coordinated force and deformation between the backfilling material and the surrounding rock in related projects.
5. By strategically arranging measurement circles along the crack path and employing DIC technology, the deformation characteristics within the fracture zone can be accurately captured, allowing for effective monitoring of the crack's entire evolution process. In future studies, this approach can be further optimized by incorporating displacement vector fields around the cracks, enabling the classification of crack types to be determined.  
Conceptualization, G.Y.; Methodology, G.Y., L.T. and X.Y.; Software, Y.Z.; Validation, Y.Z.; Formal analysis, R.W.; Data curation, L.T. and R.W.; Writing--original draft, L.T. and X.Y.; Writing--review & editing, G.W. and Y.Z.; Supervision, G.W. All authors have read and agreed to the published version of the manuscript. This research was funded by Hunan provincial department of education, grant number 23B0442. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data presented in this study are available in the article.  
Author [PERSON] was employed by the company Zhaolou Coal Mine, Yanmei Heze Energy and Chemical Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.