Moisture Damage Evaluation of Asphalt Mixtures Using AASHTO T283 and DC(T) Fracture Test

The durability of asphalt mixtures depends on two main factors: resistance to age hardening and resistance to moisture-induced damage. Antioxidants have been used in the past to control age-hardening of asphalt mixtures with some success. Currently studies are underway at the University of Illinois to develop new Antioxidant (AOX) treatments for reducing agehardening in asphalt mixes. Moisture susceptibility testing of the AOX-Modified asphalt mixtures were required to ensure that the AOX-modified mixtures did not strip excessively. The Modified Lottman Test (AASHTO T283) is the most widely used test for evaluating moisture susceptibility and is based on comparing tensile strength ratios. However, predictions of moisture damage based on AASHTO T283 have been questioned in a number of previous studies. In this study, discrepancies were observed between visually observed stripping and tensile strength ratio values obtained in the T283 procedure. Therefore, in addition to the standard AASHTO T283 indirect tensile strength testing, the Disk-shaped Compact Tension Test [DC(T)] was used to assess moisture damage based upon experimentally determined fracture parameters. For the limited number of mixtures investigated in this study, the ranking of moisture damage severity predicted by DC(T) test results was found to be in agreement with visual observations.