Effect of Asphalt Film Thickness on Short- and Long-Term Aging of Asphalt Paving Mixtures

Abstract

It is generally believed that an asphalt paving mixture should have an adequate asphalt film thickness around the aggregate particles to ensure reasonable durability (resistance to aging) of the mixture. The minimum asphalt film thickness generally recommended ranges from 6 to 8 μm. However, no significant background research data are available in the literature to support these recommended minimum asphalt film thicknesses. Some states specify minimum asphalt film thickness for mix designs. This study was undertaken to quantify the relationship between various asphalt film thicknesses and the aging characteristics of the asphalt paving mix so that an optimum film thickness desirable for satisfactory mix durability could be established. Mixes prepared with asphalt binder film thickness ranging from about 4 to 13 μm were subjected to accelerated aging using Strategic Highway Research Program (SHRP) procedures to simulate both short- and long-term aging. Both the aggregate (RD) and the asphalt cement (AAM-1)...