Investigation of the Fracture Resistance of Hot-Mix Asphalt Concrete Using a Disk-Shaped Compact Tension Test (05-2394)
Michael Parker Wagoner, University of Illinois, Urbana-Champaign
William G. Buttlar, University of Illinois, Urbana-Champaign
Glaucio H. Paulino, University of Illinois, Urbana-Champaign
Phillip B. Blankenship, Asphalt Institute

In recent years, the transportation materials research community has focused a great deal of attention towards the development of testing and analysis methods to shed light on the mechanisms of fracture development in asphalt pavements. Recently, it has been shown that crack initiation and propagation in asphalt materials can be realistically modeled with cutting-edge computational fracture mechanics tools. Likewise, only recently have appropriate laboratory fracture tests been developed to support these new modeling approaches. The goals of this paper are two-fold: (1) to present a new disk-shaped compact tension [DC(T)] test as a practical method for the determination of low-temperature fracture properties of cylindrically-shaped asphalt concrete test specimens; and; (2) to illustrate how the DC(T) test can be used to obtain fracture properties of asphalt concrete specimens obtained from field cores, following dynamic modulus and creep compliance tests run on the same specimens. Testing of four distinctly different mixtures showed that the DC(T) could detect a transition from quasi-brittle to brittle fracture due to temperature. The tendency towards brittle fracture behavior with increasing loading rate was also shown. The results obtained suggest that it might be possible to develop approximate time-temperature superposition relationships for fracture energy, which would simplify the constitutive model required for simulation of crack propagation in pavement simulations involving changing temperature and/or loading rates. Finally, the DC(T) test was applied to a field investigation of an isolated section of an asphalt overlay system which experienced fracture during the first winter of service. This case study illustrates how the DC(T) test can be used to obtain mixture fracture energy as part of an efficient suite of tests performed on cylindrical specimens from field cores.