## 4 Conclusions  
This study addressed critical engineering challenges in loess regions by systematically investigating the enhancement effects of CL-MgO carbonation solidification technology on the thermal conductivity and structural performance of loess. Through systematic experiments and microscopic mechanism analysis, the findings provide innovative solutions and new research perspectives for improving engineering stability in loess areas. The key outcomes and significance of the research are summarized as follows:  
1. Carbonation Solidification Effect and Environmental Engineering Benefits: The CL-MgO composite material facilitated the solidification of loess, while simultaneously mineralizing and sequestering CO2. After 24 h of carbonation, the degree of carbonation reached 6%, with approximately 0.6 tons of CO2 fixed per ton of MgO, forming stable magnesium carbonate minerals (hydromagnesite and magnesite). The improved soil exhibited a collapsibility coefficient below 0.015, significantly enhancing stability. This dual-effect process effectively mitigated collapsible loess issues,  
Figure 18: Microscopic mechanism. while achieving CO2 emission reduction, demonstrating substantial environmental and engineering value. 2. The Combination of CL and MgO Effectively Reduces Soil Thermal Conductivity Through Microstructural Modification: The combination of CL and MgO effectively reduced the soil thermal conductivity through microstructural modification. During carbonation, MgO's carbonated products and CL molecules alter the soil's pore structure, increasing porosity and the tortuosity of heat flow paths. Since both additives possess lower thermal conductivity than soil particles, this carbonation technique not only decreases the thermal conductivity of loess but also limits conductivity increases from environmental factors such as moisture. The improved thermal insulation properties benefit applications ranging from heating pipelines to cold-region infrastructure, while mitigating frost heave in permafrost areas. These findings can contribute to the development of sustainable building materials in loess regions. 3. Microscopic Mechanism Elucidation: The primary products of MgO carbonated solidified loess are hydromagnesite and magnesite. The hydration of MgO, combined with the cementation effect of CL, optimizes the soil structure by enhancing inter-particle bonding and filling pores, resulting in a denser soil matrix. This structural densification suppresses thermal conduction pathways, leading to lower thermal conductivity than the loosely structured remolded loess, thereby exhibiting excellent thermal insulation properties. During carbonation, CO2 sequestration is achieved, contributing to carbon emission reduction. Even after undergoing freeze-thaw cycles, although cracks may develop between particles and carbonation products at the microscopic level, the soil maintains high stability and favorable thermal performance at the macroscopic level. This stability reflects the synergistic optimization of both microscopic and macroscopic properties. 4. Future Outlook: Future research directions include validating the long-term performance of materials under cyclic freeze-thaw and wet-dry conditions to assess durability and CO2 mineralization stability in challenging environments; integrating molecular dynamics simulations with macro-scale performance data through machine learning for precise optimization of MgO-CL interactions; and exploring the co-utilization of industrial by-products to develop hybrid stabilization systems, while conducting lifecycle assessments to ensure scalable net-zero implementations. This would provide theoretical support for embankment engineering. This study systematically elucidated the microscopic mechanisms and thermal performance regulation characteristics of CL-MgO carbonated solidification technology.