Asphalt pavement design optimisation: a case study using viscoelastic continuum damage theory

Fatigue cracking is the main type of distress in flexible pavements in Brazil. Numerical models that are based on viscoelastic continuum damage (VECD) theory can help to explain the damage evolution process in asphalt mixtures, thereby allowing the proper analysis of the fatigue phenomenon. This paper aims to characterise and verify the fatigue behaviour of four test sites constructed with dense asphalt mixtures in Santa Maria, Brazil, employing field monitoring, linear viscoelastic characterisation, uniaxial cyclic fatigue testing, the simplified VECD (S-VECD) model, and FlexPAVETM software. This study’s results are coupled with a cost/benefit analysis of the evaluated test sites. The constructed sites are compared to simulated optimal pavement designed using FlexPAVETM and fatigue damage transfer function. The results indicate that this study’s methodology can predict fatigue damage evolution by identifying early cracking in two of the test sites and capturing good fatigue resistance in the other two sites. Furthermore, in both cases of early cracking, the design requirements for fatigue resistance could be met by increasing the asphalt layer thickness (optimal pavements), which significantly reduced the US$/NFATIGUE ratio. Thus, an improved cost/benefit ratio was realised for the pavements designed using this methodology and analysed using only an established fatigue criterion.