Research on design of full recycled cold-mix cold-laid asphalt mixture based on treatment of road-bridge transition section

To address the dual demands of efficient treatment of differential settlement disease in road-bridge transition sections and resource utilization of reclaimed asphalt pavement (RAP), this study developed a new type of cold-mix cold-laid full recycled asphalt mixture with high RAP content and established a two-stage performance evaluation system. The mixture uses solvent-based asphalt dispersant as the binder, with RAP content exceeding 80%. Through optimizing aggregate gradation and mix ratio, it achieves normal-temperature mixing and rapid repair. Based on the performance requirements of cold-mix mixtures for "initial opening to traffic and long-term service", a two-stage evaluation method of "initial forming + final forming" was established, clarifying the performance indicators and test standards for each stage. Test results show that under the optimal mix ratio, the initial forming performance of the mixture meets the requirements for rapid opening to traffic (stability at 25℃ is 15.79kN, brushing loss rate is 7.85%), and the final performance reaches the technical standards of hot-mix asphalt mixtures (stability at 60℃ is 15.93kN, dynamic stability against rutting is 1276 times/min). Engineering application verification indicates that the mixture has stable repair effect, can reduce material and construction costs by more than 35%, increase RAP utilization rate to 100%, and has significant engineering value and environmental benefits.