Impact of Partial Interlayer Bonding on the Load-Bearing Capacity of Multilayer Asphalt Pavements: A Finite Element Study

The structural performance and service life of asphalt pavements depend on an adequate bond between the individual asphalt layers. Insufficient interlayer bonding can reduce the load-bearing capacity of the pavement and increase its deformation under traffic loading. In this study, a finite element model of a multilayer asphalt pavement was developed to investigate the influence of different interlayer bond conditions on the load-bearing behaviour of the structure. The bond percentage and the spatial distribution of bonded areas were varied to evaluate their effects on pavement deflection and load-bearing capacity. The calculated responses were quantitatively assessed using the Darmstadt falling weight deflectometer (FWD) evaluation method according to Grätz. The results indicate that the load-bearing capacity decreases as the bond percentage decreases. However, a favourable distribution of fully bonded areas can provide sufficient load-bearing capacity even at a relatively low bond percentage of approximately 10%. The dowel effect of the layer bond causes a reduction in the maximum deflections. This can be explained by the increase in slab stiffness M1h3 caused by the layer bond, which increases the resistance of the asphalt pavement to the load. The results demonstrate the significance of both the bond percentage and the distribution of bonded areas for the structural performance of asphalt pavements.