Experimental Research on Optimum Combination of Reinforced Interlayer Bonding Materials between Base and Surface of Asphalt Pavement

The interlayer bonding performance between the base and surface of pavement has a great influence on the integrity and durability of the whole pavement structure. In order to enhance the interlayer bonding effect of this heterogeneous structure, a reinforced interlayer bonding material with a combination of permeable layer and sealing layer was designed. Self-made shearing device and pull-out device were used to carry out the interlayer shear strength and tensile strength test of the composite specimen under different interlayer oil consumption and different temperature conditions, and the influences of various factors on the interlayer strength were analyzed. Finally, the optimum combination of the reinforced interlayer bonding materials between base and surface of asphalt pavement based on the regional ambient temperature characteristics was explored. The results show that: (1) at low and normal temperatures, the interlayer strength between the base and the surface layer increases with the increase in the tack coat rate, while the interlayer strength at high temperatures first increases and then decreases with the increase in the tack coat rate. When the prime coat rate is 0.6 L/m², there is a characteristic cut-off point for the interlayer strength; (2) compared with a single permeable layer material, the use of combination material of "permeable layer + sealing layer" is beneficial to the improvement of the bonding performance between the base layer and the surface layer; (3) the combination materials of prime coat and tack coat should be selected reasonably according to the ambient temperature characteristics of the project area. For example, in areas without high temperature in summer, choosing the PC-2 emulsified asphalt tack coat with an application rate of 0.6 L/m² + 1.8 kg/m² of asphalt mixed with fiber rubber modified asphalt gravel seals to enhance interlayer bonding performance; In areas with hot and high temperature in summer, it is recommended to adjust the amount of rubber-modified asphalt in the aforementioned reinforced interlayer bonding measure to 0.9 kg/m². The research results provide experimental support for the optimal design of reinforced interlayer bonding materials between base and surface of asphalt pavement based on regional ambient temperature.