Research On Pavement Performances Of Stabilized Rubber Modified Asphalt And Asphalt Mixtures

Waste tires are often ground into crumb rubber. Crumb rubber could be made into asphalt rubber with asphalt. It has been found that asphalt rubber can not only work as SBS and other modified asphalt, but it also can reduce road noise, and it’s cheaper than other modified asphalt. However, the performance stability of the asphalt rubber is a technical bottleneck in our country. The density of crumb rubber is greater than the density of matrix asphalt, so the crumb rubber gradually sinks when it is used or stored. That is segregation, which will decrease its performance. Besides, it is proved that asphalt rubber is suitable for gap-graded and open-graded asphalt mixtures, when there is a high asphalt content. It works poorly when it is used in dense-graded asphalt mixtures. That undoubtedly increase the project cost.The stabilized rubber modified asphalt is a new material. It belongs to asphalt rubber, but it has stable characteristic. In recent years, the stabilized rubber modified asphalt shows a good performance. In addition, it is fit well for dense-graded asphalt mixtures. The stabilized rubber modified asphalt is still a new technology in our country. Its function mechanism, the selection of raw materials, technology indexes of the binder, and the gradation design methods of the stabilized asphalt rubber hot mixtures, construction technology, and quality control have not been well known. Meanwhile, relevant standards and specifications guidance are scarce.Firstly, according to lots of indoor tests, technology indexes for the stabilized rubber modified asphalt are given in this paper, with penetration grade and performance grade. Secondly volume indexes of some kinds of the Marshall specimens are tested. By analyzing the volume indexes and asphalt content, the optimized gradation ranges of stabilized rubber modified asphalt mixtures are recommended. On the basis of the results of the rutting test, low-temperature bending test and freeze-thaw splitting test, pavement performance indexes are computed. Finally, the dynamic characteristic of the stabilized rubber modified asphalt mixtures is researched in this paper. The dynamic modulus master curves and phase angle master curves are drawn up in line with the dynamic modulus test results. Moreover, the Witczak formula is revised to predict the dynamic modulus of stabilized rubber modified asphalt mixtures.This paper has a great significance on promoting the application of the stabilized rubber modified asphalt in road construction. It can provide a worthy reference to regulate the production of the stabilized rubber modified asphalt and asphalt mixtures and guide the construction of the stabilized asphalt rubber hot mixtures.