Fatigue performance of highly modified asphalt mixtures in laboratory and field environment

Abstract

High levels of SBS polymer modification lead to a bituminous binder with improved resistance to both rutting and fatigue cracking. Beam fatigue and modeling predict that, using this binder, pavement thickness can be reduced and still achieve equal or superior long term performance. To test this, a section at the National Center for Asphalt Technology (NCAT) was paved using a binder with a nominal grade of PG 88-22 for all three lifts. This pavement was constructed in August 2009 at a thickness of 145 mm compared to a standard thickess of 180 mm for the control and other pooled-fund study sections. In August 2010 an unrelated section that experienced failure was rehabilitated with a similar structure. This paper reports beam fatigue analysis and modelling and compares the results with observed field performance over both structurally sound and weak subgrades. The beam fatigue data predicts a very high endurance limit for the mixtures. Although conclusions are premature, to date neither structure shows surface distress. © RILEM 2012.