Study On Key Asphalt Indexes For Heavy Traffic

Asphalt binder is a kind of macromolecule organic polymer, typical elastic-viscous-plastic material, and its performance is relative with temperature and stress state. Asphalt pavements prevail in China, but early destructions appear around asphalt pavements because of large traffic and heavy load, so all countries are carrying out wide study with usage performance of asphalt and asphalt pavements.This paper is mainly focused on the analysis and the experiment on the indices of heavy-vehicles asphalt, by the combination with current asphalt indexes, by the contrast with SHRP experiments, heat analysis experiments, modified asphalt consistence and measuring-stress ductility instruments, and gains the index of heavy traffic asphalt pavement. The main results are as follows.1. Advantages and shortcomings of the current asphalt indices are summarized according to the investigations on usage states of typical asphalt pavements. At the same time, this paper explains uncertainty of pavement usage performance, analyzes the effect on usage performance and stress variation of asphalt pavements, and studies on the destruction mechanisms of asphalt pavements under heavy traffic. The result shows heavy traffic asphalt should satisfy the demand of anti rutting, aging and fatigue destruction under high temperature.2. According to current asphalt indices experiments and SHRP experiments, the results are analyzed by grey relative degree method using consistence instrument and measuring-stress ductility instrument.3. The effect of asphalt performance on different aging methods, different aging extents, water, oxidation and high temperature, is made the contrast between current asphalt aging experiments and SHRP aging experiments according to short and long term aging experiments. As a result, the analysis methods and aging rules of the applications of asphalt aging indices on pavements construction and usage are made certain.4. Asphalt performance indices are further analyzed by heat analysis experiment, and made further explanation from microcosmic to verify the rationality of asphalt indices.5. According to the demand of heavy load traffic,combining with rutting,beam flexural and fatigue test, the relativity between asphalt and asphalt binder performance is analyzed to make sure that 60℃viscosity, 135℃rotary viscosity, equivalent softening point T800, and softening point TR&B are key indices evaluating high-temperature performance of asphalt; 15℃penetration, PR, and equivalent breaking point T1.2 are key indices evaluating low-temperature performance of asphalt. At the same time, asphalt consistence and measuring-stress ductility are considered as complementary indices, for unmodified and modified asphalt, to evaluate high-temperature and low-temperature performance.