Numerical Modelling of Interlayer Adhesion in the Layer of Recycled Material with the Use of the Leutner Apparatus and Computed Tomography Scanning

The work has investigated the actual mechanism of the adhesion between successive asphalt layers, taking into account the macrostructure of the pavement layers, which are made of heterogeneous materials. The interaction between the joined layers was determined by applying a cohesion contact model. The parameters of the model were identified using the results obtained in the course of the actual Leutner tests. The heterogeneity of the structure was mapped based on a digital image of a tomographic cross-section. The separation of the materials included in the individual layers was performed with the use of a script in the MatLab program. Thanks to this, the batch file for the Abaqus program was prepared thoroughly. As a result, it was possible to map as closely as possible the profile of the deformation caused by the loss of the interlayer adhesion. Based on the data analysis, it was found that in the layer of the base course constructed from cold-applied recycled materials, the loss of interlayer adhesion is related to the state of non-linear mastic deformation. As a consequence, it was found that large deformations in the mastic structure would cause losses of aggregate grains in the recycled layer. In addition, a large horizontal displacement within the layer of the base course made of recycled material is one of the likely causes of edge fractures in the road structure.