## 4 Conclusions  
Irrespective of the level of stabilization, stabilized soil embankments in cold climates are inherently vulnerable to freeze-thaw cycles, which ultimately cause strength loss and volume change. To address this, our study explored the use of a MgCl\({}_{2}\) solution as an antifreeze and stabilizing agent for fine-grained soils. The experimental investigation assessed the effects of MgCl\({}_{2}\) on the plasticity, strength, and durability properties during freeze-thaw cycles.  
At a 14% concentration, MgCl\({}_{2}\) not only enhances soil compaction and dry density but also reduces the optimum water content while increasing the unconfined compressive strength by up to 38% without curing. However, it also reduces soil deformability. Additionally, the results show that 28 days of curing increases the UCS values by 5%.  
F-T cycle tests were conducted on 28-day cured clay samples at \(-10\)\({}^{\circ}\)C and \(-20\)\({}^{\circ}\)C. At \(-10\)\({}^{\circ}\)C, MgCl\({}_{2}\) solutions at 9% and 14% concentrations maintained their strength and durability indices and volume through seven cycles, outperforming both the 4% solution and the untreated samples. At \(-20\)\({}^{\circ}\)C, samples with 14% MgCl\({}_{2}\) maintained their strength and volume, whereas those with 9% showed less volume expansion and strength reduction compared to the lower concentrations and untreated samples. These results underscore the importance of a proper MgCl\({}_{2}\) concentration in preserving soil stability and durability under cold conditions and thermal stress. This ability to preserve soil integrity and volume under severe thermal stress is critical for extending the construction and maintenance season in cold regions, thereby offering additional potential cost and time savings.  
Further, the microstructural analyses through SEM, XRD, and FTIR showed that while there were no chemical changes in the soil, physical modifications occurred that improved soil performance. These changes were associated with increased concentrations of MgCl\({}_{2}\), which enhanced the soil's strength and durability.  
Finally, this study identifies MgCl\({}_{2}\) as a compelling antifreeze and stabilizing agent, significantly enhancing the durability and reliability of soil embankments in cold climates. We hope this research will open up new avenues for investigating the use of MgCl\({}_{2}\) in geotechnical engineering, particularly in regions with severe winters. We recommend that future work should include site-specific studies to optimize the MgCl\({}_{2}\) concentrations based on local weather conditions, soil types, and construction materials. Additionally, conducting large-scale field experiments will further our understanding of its practical applications for stabilizing soils against freeze-thaw challenges in cold regions.  
Figure 13: SEM images: (**a**) 28 days cured untreated sample and (**b**) 28 days cured MgCl\({}_{2}\) 14% solution treated sample.  
**Author Contributions:** Conceptualization, A.Y.R.; Methodology, A.Y.R. and B.T.; Investigation, A.Y.R.; Writing--original draft, A.Y.R.; Writing--review & editing, B.T.; Visualization, A.Y.R.; Supervision, B.T. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by the Research Fund of Istanbul Technical University, under project number MDK-2021-43154, and forms part of the Ph.D. thesis of [PERSON].  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in the current study are available on request from the authors.  
**Acknowledgments:** The authors extend their gratitude to the authorities of Istanbul Technical University for their support in this study.  
**Conflicts of Interest:** The authors declare no conflict of interest.