## 1 Introduction  
Semi-rigid base asphalt pavements, characterized by their high load-bearing capacity and cost-effectiveness [1], represent one of China's predominant pavement structures. However, they are prone to cracking due to temperature fluctuations, moisture variations, and traffic loading [2,3]. The South China Expressway (SCE), notable for its ultra-wide cross-sections, heavy traffic volumes, and extended service periods, has faced structural challenges stemming from uneven subgrade compaction during initial construction. This deficiency has led to semi-rigid base cracking under heavy-duty traffic. Compounded by environmental factors such as high temperatures, abundant rainfall, and karst geology along the route, water infiltration through the subgrade accumulates within base layer cracks, ultimately inducing reflective cracking in the pavement surface. Traditional repair techniques, particularly those targeting substructures, often necessitate extensive pavement destruction, generating substantial waste materials and significant carbon emissions. As a minimally invasive rehabilitation method, grouting technology has gained prominence in base layer stabilization due to its rapid implementation, trenchless nature, and operational safety [4]. Nevertheless, systematic evaluation criteria for treatment efficacy and research on critical process parameters remain underdeveloped, limiting their optimization for complex engineering scenarios like the SCE. Grouting technologies are primarily classified into five material-based categories: polymer, early-strength low-strength geopolymer, early-strength beopolymer, early-strength high-strength geopolymer, and early-strength high-strength waterproof geopolymer. Studies on polymer grouting materials reveal critical mechanical and durability properties. [PERSON] et al. [5] demonstrated that increasing material density induces exponential growth in yield strength, elastic modulus, and secant modulus, accompanied by a logarithmic increase in Poisson's ratio. [PERSON] et al. [6] investigated corrosion resistance, identifying minimal water-induced strength degradation but significant reductions in acidic/alkaline environments, with corrosion effects intensifying over time. [PERSON] et al. [7] investigated the effects of different components on response variables and determined the optimal formulation of polymer grouting material using a multi-objective optimization approach. In the research on geopolymer grouting materials, [PERSON] et al. [8] compared geopolymer and Portland cement concrete, demonstrating the former's superior resistance to chemical erosion, chloride ion penetration, and freeze-thaw cycles. [PERSON] et al. [9] found that geopolymer concrete exhibits superior corrosion resistance, with Portland cement concrete demonstrating approximately 51% greater strength loss than geopolymer concrete under identical corrosive conditions. [PERSON] et al. [10] further enhanced geopolymer performance through mechanochemical activation, which reduced slurry rheological complexity while improving unconfined compressive strength. While material properties dominate existing research, emerging studies focus on grouting rehabilitation effectiveness. [PERSON] et al. [11] numerically analyzed mechanical response variations in pavements before and after polymer grouting. [PERSON] et al. [12] established a comprehensive evaluation method integrating radar simulation and empirical measurements, utilizing time-frequency-domain signal characteristics to effectively assess grouting treatment effectiveness for semi-rigid pavement base layer cracks, validated through engineering case analysis and field coring verification. [PERSON] et al. [13] developed a fatigue damage model for semi-rigid base asphalt pavement structures and established a three-dimensional numerical model using the finite element method. They further conducted a comparative analysis of the mechanical responses and fatigue damage conditions of the pavement before and after polymer repair. [PERSON] et al.