Abstract：The effects of shear stress level and vertical stress on creep characteristics of recycled asphalt pavement (RAP) material were investigated by a series of direct shear creep tests. The results show that the yield shear stress level of RAP is about 0.73. The specimens at shear stress level greater than the value are observed creep rupture during the tests, and the time of creep rupture initiation is decreased with the increasing of stress level. On the contrary, the specimens are stable when the stress level is lower than the value. The variation of shear strain rate with time in loglog scale shows a series of decreasing parallel lines and can be well predicted by the threeparameter empirical creep model for soils. The vertical stress has slight influence on three model parameters but has great effect on the time of creep rupture. Under the same shear stress level, the shear strain is increased with time. The specimen with low vertical stress firstly undergoes creep rupture at low shear strain, and the shear strain at the time of failure is increased with the increasing of vertical stress. The shear strain rate under lower vertical stress is decreased faster to the minimum value than those of higher vertical stress.
2019, Vol. 40 
