Evaluation of Fatigue Life Using Dissipated Energy Methods

Abstract

Flexural fatigue is a process of cumulative damage. It is also one of the main failure modes in asphalt mixtures and flexible pavement structures. This means good prediction of a pavement’s fatigue life will help to develop and improve pavement design procedures. Different approaches have been used to characterise the fatigue behaviour of asphalt including phenomenological-based models, fracture mechanics and dissipated energy methods. This paper evaluates fatigue, paying particular attention to the dissipated energy criteria developed so far for asphalt materials. Two methods have been chosen to measure dissipated energy in tension-compression fatigue tests. Fatigue life obtained from the two different methods is compared with the traditional fatigue failure criterion Nf50, identifing both their advantages and disadvantages. An asphalt mixture has been chosen for the laboratory activity and different tension-compression fatigue tests have been undertaken at 15 Hz, at 20°C at different stress levels, in order to better understand fatigue behaviour of asphalt mixtures.