Interlayer distress characteristics and evaluations of semi-rigid base asphalt pavements: A review

Semi-rigid base asphalt pavement has been widely utilized and various interlayer distresses occur during its service life due to temperature, vehicle loads and water, which weaken the interlayer performance between the base and surface layers. This review primarily investigates the mechanisms of interlayer distress in semi-rigid base asphalt pavement, as well as the evaluation methods for interlayer performance and the methods for treating interlayer distress. Interlayer distress is caused by the weakening of interlayer performance, manifested specifically in inadequate interlayer bonding strength and cracking resistance. Accordingly, researchers have proposed various methods for evaluating interlayer performance, including shear tests, tensile tests, torsional tests, fatigue tests, and non-destructive testing methods. Measures for treating interlayer distress can be categorized into pavement materials and structural design, application of tack coats, and installation of interlayers. Among them, asphalt emulsion is the most commonly used tack coat material to enhance interlayer bonding performance significantly. Meanwhile, during the application of tack coats, mechanical parameters should be controlled strictly and ensure high construction quality. Interlayers installation was proven to delay and prevent crack propagation effectively, reducing crack-related distress significantly. The lower life cycle cost (LCC) of permanent semi-rigid base asphalt pavement makes it present high application potential. It is recommended to consider interlayer installation in semi-rigid base asphalt pavement design and take appropriate measures to enhance interlayer performance effectively.