Evaluation of fatigue behaviour of bituminous mixtures using a 4-point bending test

One of the key structural failure modes found in bituminous pavement layer is flexural fatigue, resulting from repeated loading application of traffic-induced stresses. It is true that, in recent years, the 4-point bending test (4PBT) have been widely applied in order to characterise fatigue behaviour of asphalt mixtures. In this research paper, the test was used to investigate the fatigue characteristic of one unmodified and two quite different polymer modified asphalt mixtures. The 4PBT results indicated that under the same conditions, an increase trend in flexural stiffness as frequency increased from 1 Hz to 30 Hz for all three mixtures. The test results also presented an obvious difference in the initial stiffness loss behaviour of mixture types tested at 200 microstrain. In addition, in terms of fatigue lines, the 4PBT results showed the polymer modified mixtures have had a better fatigue performance in comparison with the performance of conventional mixtures as expected.