Mechanistic Evaluation and Rut Prediction of Bituminous Mixtures Under Static and Dynamic Pore Pressure Conditions for Different Traffic Levels

Moisture is considered as a significant factor in the long-term performance of bituminous mixture, with its effect further intensified by varying traffic conditions on the pavement. This study investigates the combined influence of moisture and compaction on the performance of bituminous mixtures, with a particular focus on the roles of static and dynamic pore pressures. Static moisture exposure is simulated through conventional soaking durations of 40 minutes and 24 hours, while dynamic conditioning is simulated using the Moisture Induced Stress Tester (MiST), which replicates field induced moisture effects. The study was carried out with high, medium, and low traffic conditions by applying compaction levels of 75, 50, and 35 blows, respectively. The initial phase of the study focused on assessing the impact of dynamic pore pressure on bituminous mixtures using non-destructive testing techniques such as Ultrasonic Pulse Velocity (UPV), X-ray Computed Tomography (CT), and air void analysis through the CoreLok apparatus. The study further explored the mechanical properties such as Marshall stability and flow. Further, the rutting behaviour was evaluated using moisture susceptibility parameters such as Stripping Inflection Point (SIP), Stripe Slope and Inverse Stripe Slope, Stripping Number (SN), Stripping Number Life (LCSN) and Stripping Life (LCST). Similarly, the Rut Performance Parameter was evaluated using factors such as Total Rut Depth (TRD), Corrected Rut Depth (CRD) and Percentage rut caused by Stripping, Creep Slope and Inverse Creep Slope, Rutting Resistance Index (RRI). Finally, a rut prediction model was formulated, incorporating static and dynamic moisture conditions across three traffic levels. The test results prove that the rut depth is highly affected by the dynamic pore pressure. It is also inferred that the high compaction level reduces the rut depth in a range of 17% to 50% compared to lower compaction level when subjected to high pore pressure.