Abstract
In order to determine the shear stiffness at the interface between asphalt layers and to take into account the interactions of repeated traffic loading, acceleration and braking processes as well as temperature influence, a complicated apparatus for cycling testing of the interlayer bond (CTIB) has been developed. An extensive experimental procedure has been created to include all factors that influence the interlayer bond. Using the experimental results, a master function for the analytical assessment of the shear stiffness has been established. The regression which approximates most accurately the experimentally determined shear stiffness values is the sigmoid function. Through implementation of the master function into a finite element program the fatigue status of asphalt pavements, which is affected by the interlayer bond of different quality, have been calculated over the service life of 30 years using the German method for computational design according to RDO Asphalt 09. The results presented below are based on the results of IGF project “Cyclic Shear Stiffness and Shear Fatigue Testing for Evaluation and Optimization of Interlayer Bond in Asphalt Pavements”, supported by the Association of Industrial Research Communities (AIF) of the German Asphalt Institute (DAI) in cooperation with TU Braunschweig.
Highlights
The construction of asphalt concrete pavements usually consists of a surface course, a binder course and a base course
The main objective of this study is to develop a master function for analytical assessment of the shear stiffness, which takes into account the dependence between shear stiffness, temperature, shearing frequency and normal stress in order to implement the established master function in the finite element program SAFEM (Semi-Analytical FE Method) [1]
Five different interlayer bond configurations were defined for the layer boundaries between surface and binder course, as well as between binder course and base course: 1. Full interlayer bond (FIB): theoretical case
Summary
The construction of asphalt concrete pavements usually consists of a surface course, a binder course and a base course. The interlayer bond (IB) should be produced as a full-surface and rigid connection between the individual layers of the asphalt pavement in order to allow the transmission of shear stresses between them. When transferring shear stresses across the layer interface, these three factors act simultaneously in different proportions, depending on the asphalt mixes, the temperature, the normal pressure, and the type and quantity of the bitumen emulsion
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