Study of the permanent deformation of asphalt mixtures in the field: A multiscale approach

Rutting in asphalt concrete layers is a longitudinal depression in wheel paths caused by traffic load repetitions. Different tests and analysis have been proposed to investigate the phenomenon, although few studies of resistance to rutting can be found regarding a multiscale approach from binder to field in literature. Thus, the main objective of this study is to evaluate the behavior of the different scales against the phenomenon of permanent deformation for different binders, mixtures and in-service pavements, verifying the performance relationship between them and how the properties can be correlated. For this, eight monitored asphalt pavements were chosen during road rehabilitation. They consisted of conventional, SBS modified and rubber binders, evaluated in the laboratory for linear viscoelastic characterization and permanent deformation tests. Track rutting was also observed in the field during the first year for comparison with laboratory results. The experimental segments monitored in this research showed that mixtures with SBS and rubber-modified binders returned lower Rutting/N ratios. It was possible to conclude that binders modified using SBS polymer and rubber have greater stiffness and lower phase angles at high temperatures. Asphalt mixtures showed greater stiffness and lower phase angles at high temperatures for mixtures consisting of binders modified by SBS polymer. Flow Number (FN) results were also higher for these mixtures, suggesting better performance in the field. In the mixture scale, the |E*|/sinφ (54 °C; 1 Hz) show the best correlated-with-field rutting in this research, to binder scale, the Jnr parameter was the one that best represented the behavior observed in the field