Fatigue Behaviour of Bituminous Materials: From Binders to Mixes

Abstract

ABSTRACT Test procedures, aiming at measuring fatigue directly on bituminous binders, are increasingly used. The purpose of this paper is to investigate the relevance of this type of binder fatigue tests and to compare the results with laboratory fatigue properties of the corresponding mixes, using one mix composition for all binders, and similar fatigue tests conditions. Eight binders were selected, derived from two crude sources, including an oxidised and two polymer modified samples. All fatigue tests were performed at equi-stiffness levels. A very good relation was seen for the ε6 value (strain level at which fatigue occurs after one million cycles) in binder and corresponding mix fatigue tests, at least for the non polymer modified binders. The polymer modified samples showed an improved fatigue resistance in binder tests, which was only partially reflected in the asphalt mix tests. In addition, more structured binders, as for example after oxidation, showed better fatigue resistance especially at low strain levels, and under the test conditions used. From this study we can conclude that binder fatigue tests are well related to laboratory mix fatigue behaviour for a given mix composition.