Effect of temperature on fatigue tests parameters for conventional and asphalt rubber mixes

Fatigue cracking is a major form of distress in asphalt pavements all over the world. Traditionally, fatigue has been analysed using a phenomenological approach, which relates the number of cycles to failure with the imposed strain or stress level. More recently, advanced concepts of continuum damage theory have been applied to investigate damage evolution in asphalt mixes. Another approach relates the damage evolution with the slope of the stiffness reduction curve during uniaxial fatigue tests. This approach is revised in this study to analyse four-point bending (4PB) fatigue tests and to consider non-linear effects over a wider range of imposed strain amplitudes. In this paper, the three approaches are applied to analyse the effect of temperature on the results of 4PB tests performed on hot mix asphalts using different aggregate gradation (dense, open and gap graded) and different asphalt binders (conventional and asphalt rubber). All results clearly showed the dependence of the fatigue parameters on temperature, in that faster damage evolution was observed for mixes at lower temperatures. The results also showed that the asphalt rubber mixtures had lower susceptibility to temperature variations compared to the conventional mixtures.