# An Experimental Study for Swelling Effect on Repairing of Cracks in Fine-Grained Clayey Soils
## 4 Conclusions  
The presented study is based on an experimental assessment to understand the self-healing process in cracked fine-grained clayey soil modification. A self-healing process is a well-known event for an earth-fill dam's core to reinforce against structural failure. The study aimed to investigate the self-healing capability in the Kalgan Chay Dam's core clay near Tabriz, northwest Iran. The following categories can be applied to the findings of this study:  
* By adding the weight percent of Bentonite to the clay soil, the water content liquid limit and plasticity index are increased, and the increase in plasticity index leads to further soil cohesion and further hydration and swelling of the soil, which in turn greatly contributes to the sealing of the created cracks. However, since the increase in the plasticity index causes cracks in the drying period, the increase in the weight percentage cannot exceed the standard limit. Based on the current recommendations, the plasticity index, in this case, should not exceed 25. Therefore, according to the obtained results, it is impossible to use 12.5% Bentonite in the mixture with clay soil;
* Regarding Bentonite's swelling potential and expansion property, the soil's swelling potential is increased by adding a percentage of Bentonite to the clay soil, which has a key role in repairing the soil dam core cracks. By adding 12.5% Bentonite to the clay soil, the swelling potential of the mixture increases more than six times, from 0.1 to 0.63;
* By adding 10% Bentonite to the clay soil, the swelling pressure of the clay soil is increased by three times, which leads to an increase in the repairing power of the samples;
* Regarding the previous points, in the present research, the best combination of Bentonite with core clay repairs the cracks and is applicable in clay dam cores with a mixture of clay with 10% Bentonites;
* In this research, in order to verify and objectively observe the repairing of cracks, the researchers used a pinhole test. By comparing the test on the core clay sample, using a combination of clay with 10% Kaolin and a combination of clay with 10% Bentonite, it was noted that only in the sample of clay combined with 10% Bentonite did the flow of water gradually decrease during the test, so that even at the end of the test, despite the increase in the head, the speed of water outflow was diminished and almost stopped, which indicated the closing of the hole and repairing of the cracks.  
M.N. and A.E.I.: writing--original draft preparation, methodology, investigation, resources; M.A.: conceptualization, validation, visualization, formal analysis, methodology; F.B.S. and M.H.B.: supervision, writing--review and editing; R.D.: supervision, writing--review and editing. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Figure 12: Repairing of the sample holes in the pinhole test.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The study did not report any data.  
**Acknowledgments:** The authors wish to thank the Department of Civil Engineering, University of Tabriz for providing permission to conduct the geotechnical investigations. In addition, the authors would like to thank the anonymous reviewers for providing invaluable review comments and recommendations for improving the scientific level of the article.  
**Conflicts of Interest:** The authors declare no conflict of interest.