Abstract: The use of clay-wrapped fine sandy soil for highway subgrade slope filling is an innovative technique, but its compaction parameters and quality control standards remain to be clarified. To verify the feasibility of this technique and optimize the construction parameters, systematic compaction tests were conducted on a test section of a high-grade highway. Different compaction machinery combinations were employed for the operations, and the compaction quality was comprehensively evaluated using multi-index testing methods. The results show that: (1) The clay wrapping structure effectively maintains stable internal moisture within the sandy soil subgrade, verifying its engineering applicability. (2) Optimal compaction effectiveness for the fine sand filler is achieved with 6 passes of alternate longitudinal and transverse rolling using a bulldozer and a loose paving thickness of 35 cm. (3) Compared to the subgrade reaction modulus K₃₀, the dynamic deformation modulus E_vd demonstrates significant advantages in testing efficiency, data accuracy, and field adaptability, and is recommended as the core control indicator for the compaction quality of sandy soil subgrades. The research findings provide a scientific basis for construction quality control in similar projects.

Key words: Highway Subgrade, Cohesive Soil Edge-Wrapping, Fine Sandy Soil Fill, Compaction Process, Dynamic Deformation Modulus