Cement-stabilized macadam (CEM-SM) base layers on highways are prone to early shrinkage cracking in extremely cold and arid regions, mainly caused by the large drying shrinkage of traditional cement-stabilized base materials. A multi-component solid waste cementitious material (SWCM) was designed based on the response surface method. The synergistic reaction mechanism of SWCM was analyzed using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). A shrinkage testing system was developed to evaluate the anti-cracking characteristics of stable macadam using multiple solid waste cementitious materials (SWCM-SM), and the strength growth law and frost resistance were analyzed. The results show that the Box–Behnken response surface model was used to obtain the optimal parameter combination for SWCM, including 60% slag, 30% steel slag, and 10% desulfurization gypsum. The compressive strength and flexural strength of SWCM-SM were 24.1% and 26.7% higher than those of CEM-SM after curing 180 days. The frost resistance of SWCM-SM was basically equivalent to that of CEM-SM, and the dry shrinkage strain of SWCM-SM was reduced by 30.7% compared to CEM-SM. It can be concluded that steel slag and desulfurization gypsum stimulate the hydration reaction of slag, thereby improving the bonding strength. Compared to CEM-SM, SWCM-SM exhibits slower hydration reaction and longer hydration duration, exhibiting characteristics of low early strength and high later strength. The early microstrain of the semi-rigid base layer is mainly caused by the occurrence of early water loss shrinkage, and the water loss rate of SWCM-SM is lower than that of CEM-SM. This study concludes that SWCM has good early crack resistance performance for stabilized crushed stones.

The performance of cement-stabilized reclaimed asphalt pavement (CSRAP) mixtures is closely related to the structural evolution and bonding behavior of the interfacial transition zone (ITZ). This work explores the elemental distribution characteristics, elastic modulus, and molecular interaction mechanisms between reclaimed asphalt pavement (RAP) and cement in the ITZ from a multi-scale perspective. SEM-EDS analysis and nanoindentation testing indicate that the ITZs formed at the natural aggregate/cement and RAP/cement interfaces gradually densify with curing time. However, the aged asphalt film inhibits the cement hydration reaction and reduces the elastic modulus of the ITZ. EDS analysis indicates that as curing time increases, the Ca/Si ratio and spatial distribution of hydration products in the ITZ undergo continuous changes, which gradually transform from low-density C-S-H to high-density C-S-H. Molecular dynamics simulations revealed the interaction mechanism between C-S-H and RAP, indicating that surface interfacial bonding constitutes a thermodynamically spontaneous process primarily governed by van der Waals forces. The asphalt film restricts Ca ²⁺ migration, transforming multi-layer adsorption into single-layer enrichment, thereby weakening interfacial bonding. This study investigates the physicochemical properties and molecular bonding mechanisms of RAP/cement ITZ, providing a theoretical basis for optimizing interfacial structures and enhancing the performance of cement-stabilized reclaimed asphalt pavement materials.