Compaction quality plays a vital role in the long-term performance of highways, thereby making quality control (QC) of compaction an essential aspect in highway projects. The prevalent approach regarding QC of compaction primarily depends on manual manipulation of compaction parameters during the construction process and sporadic testing after completion. However, the former method is significantly affected by human factors, whereas the latter entails destructive detection and low efficiency; the latter method also fails to provide a comprehensive representation of the state of compaction across the entire work area of highway projects. Consequently, to achieve QC of compaction, this study used roller-integrated compaction monitoring (RICM) technology combined with the real-time kinematic–Beidou navigation satellite system (RTK–BDS). Initially, the compaction meter value (CMV) and compaction power per unit volume (E) were chosen as the real-time monitoring indexes for assessing the quality of compaction. Subsequently, a case study on the Hengyong Highway Project in China was conducted. The findings revealed that CMV exhibited a stronger correlation with compactness, resulting in smaller data dispersion and higher data stability. Thus, this study chose CMV as the characterization index of the compaction quality of high and low liquid limit (ωL) silt subgrades and constructed a fast compaction quality assessment method based on CMV and the spline interpolation method based on Green’s function to obtain estimates for compaction quality over the entire work area, enabling QC of silt subgrades. The results showed that the proposed method facilitated a swift and uninterrupted evaluation of the compaction quality over the entire construction area. Thus, the proposed method can facilitate the effective prevention of compaction quality defects, thus enhancing the overall quality of highways.