Book Description

This report summarizes a 2 1/2 year research effort toward developing a procedure by which a standard laboratory can define appropriate modifiers to recycle old paving-grade asphalt in hot central plant-recycling operations. Literature reviews and discussions with expert asphalt chemists, technologists, research institutions, and oil companies were conducted. Field-aged asphalt cores from different climatic areas and modifiers were collected and characterized. Characterization using physical and chemical tests were performed on aged binders, modifiers, fresh and RTFO aged blends, and recovered recycled aged binders. Recycled Marshall mixtures were prepared and periodically characterized during accelerated oven aging. Chemical parameters identified were used to establish the laboratory test matrix. These parameters included the Polar/Saturate (P/S) ratio and percent generic aromatics as determined by a modified Clay-Gel (ASTM D2007) method. The results indicate that some chemical and physical properties can be correlated and that modifier/aged asphalt compatibility can be assessed by chemical methods developed in this study. Finally, a tentative recycling agent selection specification has been developed, but more research is required for validation. Originator supplied keywords include: Aged Asphalt Rejuvenation, Hot Central Plant Operation, Recycling Agent Selection, Physical and Chemical Methods, Chemical Composition by Clay-Gel and Compatibility by Heithaus, Asphaltene Redispersion, Asphaltene Peptizability, Maltene Peptizing Power, Recycling Agent Specification.