Study on the Filler Composition Optimization and Performance Evaluation of Cold-Patch Asphalt Mixture

Filler dramatically affects the rheology of cold-patched asphalt (CPA) slurry, as well as the related mechanical properties; its physical and chemical properties will also affect the road performance of cold-patch asphalt mixture (CPAM). In order to optimize the filler composition ratio for CPAM, this study uses an orthogonal test to determine the optimal ratio of bentonite to cement, partially substituting mineral powder. Additionally, a performance verification test suitable for CPAM is designed and performed. The results indicate that the total filler dosage is 4.3%, the proportion of mineral powder replacement is 50%, and the ratio of bentonite to cement is 0.2:1; the forming strength, residual stability, and freeze-thaw splitting strength of CPAM are improved by 7.37%, 20.95%, and 17.13%, respectively, and the water stability is significantly enhanced. Scanning electron microscope images show that the cement and bentonite are dispersed as fillers in CPA, and a hydration reaction occurs, which reveals the mechanism of the optimized cold-patched filler ratio related to performance enhancement.