01629821

Component

The accurate characterization and prediction of asphalt mixture properties with regard to pavement service life are becoming more important as increasingly powerful pavement design and performance prediction methods are being implemented. Oxidative aging, as a major distress mechanism of asphalt concrete pavements, causes the asphalt concrete to stiffen and embrittle, which leads to a high potential for cracking in pavements. Thus, an improved understanding of the factors that affect oxidation reactions will inform improved laboratory aging procedures and predictive oxidation models. An experimental plan that includes laboratory binder aging, laboratory mixture aging, and field-aged materials was implemented in this study to elucidate the factors that affect oxidation mechanisms in asphalt concrete. The relationships between rheological and chemical aging index properties were used to detect differences in the oxidation mechanisms. The results demonstrate that oxidative aging at temperatures over 100°C can alter the oxidation mechanisms and should be avoided in long-term laboratory aging. The results also demonstrate that aging mixtures in a compacted versus loose mixture state can determine whether the oxidation reaction is diffusion- or kinetics-controlled. The application of pressure and the aggregate interactions with the binder may also impact the oxidation reaction, suggesting that standard binder aging methods cannot fully reflect mixture aging. A comparison between binders extracted from laboratory-aged loose mixtures and from field cores suggests that field aging is diffusion-controlled underneath the pavement surface. In addition, oxidation at the pavement surface differs from oxidation in laboratory-aged loose mixtures even though both pavement surface and loose mixtures are speculated to experience kinetics-driven oxidation, suggesting that ultraviolet photo-oxidation and/or other field variables may affect pavement oxidation, which cannot be easily replicated in the laboratory.

This paper was sponsored by TRB committee AFK20 Standing Committee on Asphalt Binders.

01618707

17-05969

English

20p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; References; Tables

Aging (Materials); Asphalt concrete; Field tests; Kinetics; Laboratory tests; Oxidation

Diffusion

Highways; Materials; Pavements

Transportation Research Board Annual Meeting 2017 Paper #17-05969

TRIS, TRB, ATRI

Dec 8 2016 12:24PM