POLYMER MODIFIED ASPHALT CEMENTS

This work describes the characterization of aged polymer modified bitumens to evaluate their potential for recycling. A tri-block co-polymer modified binder was selected and characterized using standard bitumen qualification techniques, i.e., the Superpave PG protocol. We developed a procedure to characterize the relative concentration of polymer in asphalt cements by gel permeation chromatography. Infrared spectrographic, thermogravimetric and rheological techniques were used to identify changes in the binder components as a result of aging. A correlation between field aging time and simulated aging by PAV was developed; PAV with humidity proved to be the best prediction. A comparison was established between the field aged materials and a series of lab aged binders. All binders were characterized with respect to their composition and rheological properties. In general, residual polymer was detected using gel permeation chromatography analysis except when extensive oxidative age hardening of the binder had occurred. Recycling of this material will require additives to restore the desired rheological properties to the binder blend.