Impact of Three-Dimensional Stress Pulse Configurations and Rest Period on Permanent Deformation Characteristics of Asphalt Concrete Mixtures

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Description
Asphalt concrete (AC) layers in airfield and highway pavements are subjected to complex 3-D stress states due to moving load and maneuvering effects of heavy trucks and aircrafts in highway and airfield pavements. The conditions AC layers are subjected to

Asphalt concrete (AC) layers in airfield and highway pavements are subjected to complex 3-D stress states due to moving load and maneuvering effects of heavy trucks and aircrafts in highway and airfield pavements. The conditions AC layers are subjected to in pavements evolved significantly with increasing truck loads and repetitions. In addition, truck platooning was recently introduced with the development in automation and connected technologies in the transportation industry. Reliability of pavement designs against permanent deformations can be compromised under such traffic loading conditions.The main goal of this dissertation is to characterize permanent deformation resistance of asphalt mixtures under various stress pulse configuration with varying stress states and rest periods. While the effects of loading duration and stress states were commonly studied in the literature, rest period effect was relatively less understood. Therefore, the focus of this thesis is to assess the effect of rest period using advanced triaxial permanent deformation experiments simulating stress states of truck platoons and maneuvering aircrafts. An experimental program was developed to assess the influence of rest periods under varying stress pulse configurations and paths on the permanent deformation of AC layers. Result showed that increasing rest periods led to increase in permanent deformations consistently about 2-3 times in high temperatures due to the hardening-relaxation or hardening–softening mechanisms. Rest period impact was found to be as important as temperature and stress magnitude for asphalt mixture’s permanent deformation resistance. ii Furthermore, the results showed that the changing stress paths had a significant effect on permanent deformation resistance when compared to conventional repeated-load experiments. A novel repeated load permanent deformation experiment was developed as part of the thesis research. The main idea of the experiment was to induce dynamic and independent stress pulses in the axial as well as the horizontal direction as confinement. With the individual pulsing in axial and horizontal direction, stress states simulating platoon moving loads or aircraft shear loading can be simulated and compared to conventional flow number experiment with dynamic axial pulsing with constant confinement pressure.
Date Created
2024
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