Study on crack propagation behavior of bridge deck asphalt pavement

Crack is a typical distress on bridge deck asphalt pavement (BDAP), which destroys the integrity and continuity of the pavement structure. However, the research on the crack propagation mechanism of BDAP is still limited. In this study, the three-point bending test was performed to investigate the propagation process of cracks in BDAP. Pre-cracks were set in the specimens with different depths (8 mm, 12 mm, 15 mm) and 4 mm widths, and two asphalt rubber hot-mix (ARHM) mixtures (ARHM-13 and ARHM-20) were selected. The critical fracture load, fracture energy, and fracture toughness were compared to investigate the crack resistance of ARHM-13 and ARHM-20 mixtures. In addition, the upper and lower layers of double-layer composite pavement specimens were fabricated with ARHM-13 and ARHM-20 mixture, respectively. The propagation process of the top-down crack (TDC) and reflection crack (RC) were investigated at different locations on the specimens. The test results show that the crack resistance of ARHM-20 mixtures is greater than that of ARHM-13 mixtures, and ARHM-20 mixtures should be used in the lower layer of BDAP to limit the propagation process of the reflection crack to the upper layer. The cracks propagated firstly from the RC and formed a through crack at the TDC in the specimens under the three-point bending loading action. The presence of TDC was found to accelerate the crack propagation of RC and exacerbate the failure of the BDAP. The crack length and deflection angle were determined by the pre-crack location. Furthermore, the decrease in temperature led to an increase in crack propagation velocity. The average propagation velocity increased from 0.03 mm/s to 0.55 mm/s as the temperature decreased from 20 ℃ to −20 ℃.