Study On Creep Properties Of Asphalt Based On A New Creep Tester

With the development of transport industry and acceleration research of pavement materials, it’s become a tendency that researchers pay attention to asphalt and asphalt viscoelastic behavior and road performance for the study of asphalt pavement. In this paper, using the rotary shear creep tester which was independently developed by Road Department of Dalian University of Technologyanalyze, evaluating the creep properties of different types of asphalt which aims to provide a new method and mean for the research and application of a viscoelastic mechanical behavior of asphalt to promote the adhibition of viscoelasticity theory and it’s trials equipment in test of asphalt pavement.This paper describes the working principle and test methods for asphalt rotary shear creep tester and select six kinds of asphalt to test conventionally.Secondly, using the creep tester study the influence of different types of asphalt, temperature, stress levels or other factors on the asphalt single creep strain, creep recovery rate, creep stiffness and other indicators. The results show that the asphalt’s creep strain which are on the same stress level increase while the creep recovery rate, creep stiffness decrease with the temperature increase. Besides, the the size of creep strain increasing become bigger and bigger. Under20℃low stress level, there is little effect on the creep stiffness from stress level while most asphalt creep recovery rate decrease with the stress level increasing. Power function S(t)=B-m can be a good characterization of the relationship between creep stiffness of asphalt and time. Different grades of asphalt’s creep properties varies greatly. Adding modifier can effectively reduce the total asphalt’s deformation and even can increase the elastic deformation ratio of the deformation. The aging process can change the creep properties of asphalt greatly.The regenerated catalyst’s addition can increase the viscosity composition of the aging asphalt and restore asphalt’s viscoelasticity.Thirdly, using the creep tester to study the influence of asphalt type, stress level and creep recovery times on the asphalt’s creep recovery properties The results shows that different types of asphalt creep response rates varies widely when the temperature is20℃. Creep recovery rates of asphalt and recycled asphalt, are relatively little while the creep recovery rates of modified asphalt and aging asphalt are relatively large. Repeated creep recovery test can distinguish the viscoelasticity of modified asphalt better. Under20℃low stress level, creep recovery rate increase gradually and stabilize while the single maximum shear strain decrease and gradually stabilized with the increasing load times. Finally, using BBR trials to study different types of asphalt’s low-temperature creep properties, the results showed that aging process can increase the asphalt’s low-temperature creep stiffness and reduces the changing rate of asphalt stiffness, thereby reduce the low-temperature properties of asphalt. The regeneration process can effectively reduce the asphalt’s low-temperature stiffness and increase the asphalt’s changing rate of stiffness. Modified asphalt can effectively reduce low-temperature creep stiffness of asphalt, but it also reduces the changing rate of stiffness. It should be combined with other tests to evaluate the low-temperature performance for modified asphalt. Burgers model can describe the asphalt, modified asphalt, aging viscoelasticity of asphalt and recycled asphalt very well. It can further prove the rationality of use Burgers model to fitting asphalt materials.