Review: Shear Properties and Various Mechanical Tests in the Interface Zone of Asphalt Layers

Over four decades, researchers have extensively focused on bonding flexible pavement layers. Scholars concentrated the partial or complete lack of interlayer between asphalt layers, which is primary cause premature failures, such as cracking, rutting, slippage wearing courses, and decline in life. These defects are observed within high horizontal force areas owing to increased speed, braking, sharp angles when entering exiting highways variations paving materials, traffic load, climatic factors. Various studies investigated debonding pavements, test methods been developed find effective solutions. This review aimed at summarising discussing certain factors influencing shear strength performance, tack coat material, surface characteristics multi-layer construction different mechanical tests. First, interface zone area its Effect performance reviewed. Subsequently, types materials their effects quality clarified. Finally, linear relationships Ability nanofibers improve emulsion properties discussed. However, no agreement optimum could be obtained variety surfaces. Hence, a milling recommended for higher strength. The most used method verifying strengths, continuous research endeavours analyse pavements.