Multiscale characterization of frost resistance in modified cement-stabilized macadam: Integrating mechanical, capacitive, and microstructural assessments

This study presents a comprehensive multi-scale evaluation of the frost resistance of cement-stabilized macadam (CSM) modified with multiple admixtures. A frost-resistant variant (FCSM), enhanced with expansive agents, latex powder, superabsorbent polymers, and polypropylene fibers, was systematically compared to conventional CSM. The evaluation incorporated mechanical tests, capacitive sensing, ultrasonic velocity analysis, acoustic emission monitoring, and microstructural investigations using Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP). Under freeze–thaw cycling, the FCSM demonstrated significantly greater strength retention, mass stability, and internal compactness. Capacitance degradation exhibited strong correlation with both ultrasonic velocity reductions and mechanical performance loss, confirming the reliability and sensitivity of capacitive sensing for frost damage detection. Acoustic emission results further indicated suppressed crack propagation in FCSM during compression. Microstructural analysis revealed that the admixtures effectively reduced detrimental porosity and improved matrix integrity. These findings underscore the effectiveness of capacitive sensing as a quantitative, non-destructive evaluation method, and highlight the importance of integrating mechanical, physical, and microstructural parameters for the robust assessment of frost durability in cement-bound road materials. • A multiscale evaluation framework combining mechanical, capacitive, acoustic, and microstructural methods was established. • Capacitive sensing exhibited high sensitivity and strong correlation with frost-induced deterioration. • Microstructural characterization validated macro-level findings and revealed porosity reduction mechanisms.