Comparison of Laboratory and Field Asphalt Aging for Polymer-Modified and Warm-Mix Asphalt Binders

Abstract

The laboratory aging tests for binders were developed based on Strategic Highway Research Program (SHRP) tests in the 199s (i.e., performance grading); the applicability of performance grade (PG) to recently developed tests, such as multiple stress creep recovery (MSCR), is not clear. In addition, the ability of laboratory aging to represent field pavement aging, especially when polymer-modified asphalt (PMA) and warm-mix asphalt (WMA) binders are used, has been a concern to paving practice. This paper investigates quantitatively the level of laboratory aging compared to the field aging for both the control hot-mix asphalt (HMA) binders and WMA and PMA binders. The study focuses on a number of binder parameters, as well as evaluating whether the current laboratory aging conditions (loose-mix oven aging) will provide correlation to field short-term aging. HMA and WMA binders from four field projects that covered different climatic zones, pavement structures, and materials were selected. Binder properties including high-temperature PG, MSCR nonrecoverable creep compliance, low-temperature binder PG, and fracture energy were used for analysis. The results show that the laboratory rolling thin-film oven (RTFO) aging method is not sufficient to simulate field short-term aging conditions for most cases except for the low-temperature PG test. The aging of asphalt binder is parameter sensitive; depending on the parameters used, the comparison results between laboratory aging and field aging could be different. The effect of aging on PMA binder, especially when mixed with Sasobit additive, differs from non-polymer-modified binders. Limited results from non-polymer-modified binder mixes suggested that loose-mix oven aging at 85°C for 2, 5, and 7 days appears to provide a reasonable simulation of field pavement aging right after compaction ( years), 1.8 years, and 3 years.