Low Temperature Binder-Aggregate Adhesion and Mechanistic Characteristics of Polymer Modified Asphalt Mixtures

In this study, binder-aggregate adhesion and mechanistic characteristics of neat and polymer modified asphalt mixtures were investigated at low temperatures. The lap-shear test and environmental scanning electron microscope (ESEM) in situ tensile test were conducted to examine the adhesion and fracture morphology of neat and modified binders. The mechanistic properties were obtained from indirect tensile strength test and indirect tensile cyclic load test. It was found that lap-shear strength and toughness energy were functions of temperature and polymer concentration. The ESEM in situ tensile test indicated that the modified binders exhibited improved adhesion properties and had higher number of asphalt fibrils with longer lengths relative to the neat asphalt. In general, the improvements in the mechanistic properties were due to the improvements in the binder-aggregate adhesion behavior at low temperatures. It was found that the horizontal plastic deformation rates of modified mixtures were lower than the neat ones and were related to the lap-shear strength and toughness energy.