Investigating the fatigue endurance limit of HMA mixture using RDEC approach

The endurance limit is level of strain below which fatigue damage does not occur for any number of load repetitions. The evaluation and the determination of the fatigue endurance limit requires for testing at low strain levels. Various extrapolation methods were presented for the determination of fatigue lives at low strain levels. In this research study, the four point beam fatigue tests were conducted in accordance with AASHTO T321 using a semi sinusoidal loading at 10 Hz for 70, 150, 200, 250, 400, 700 and 1000 microstrain levels. The test data were investigated via the RDEC approach and PV–Nf50 unique relationship to obtain the fatigue endurance limit. The results showed that there is a transition point in semi log strain–Nf50 curve when the curve is regressed using the power law relation. The results also showed that the number of load cycles corresponding to transition strain (endurance limit) is different with load cycles corresponding to PVL (1.1E+7).