Research On The Interaction Mechanism Of Crumb Rubber Modified Binders Based On The Raw Material Properties

Crumb tire rubber is the main source of solid waste. It can not only effectively reduce the pollution of the environment and recycling of resources, but also can significantly improve the mechanical properties of asphalt pavement by using the crumb tire rubber powder for asphalt pavement construction. Crumb rubber modified(CRM) binders can improve pavement anti rutting, cracking, water damange resistance and anti-fatigue cracking performance. In addition, rubber asphalt pavement has excellent characteristics such as good flatness, high skid resistance and noise reduction performance, etc. However, the reaction mechanism under different process conditions of rubber asphalt is still unknown at present, which leads to poor performance of rubber asphalt. And CRM binders have not performed as well as engineers had hoped. Therefore, it becomes the key technical problems of “wet process” rubber asphalt for how to produce and preparate asphalt rubber with excellent performance and to explore the mechanism of the reaction under different reaction conditions.First of all, the viscosity, dynamic shear rheometer(DSR), infrared spectroscopy(FTIR) and gel permeation chromatography(GPC) test methods, together with statistical analysis methods were used to study the production process parameters and the internal reaction mechanism of CRM binders based on the research at home and abroad in the paper. Furthermore, the optimum process parameters of CRM binders were determined by establishing the multi index model of CRM binders’ production parameters. Secondly, CRM binders were produced using different production processes crumb rubber, including cryogenic processing method and ambient processing method. Then the performance of CRM binders affected by crumb rubber content and particle size were studied. Finally, mechanical properties of CRM binders with different sources of base asphalt were also investigated by using three different kinds of base asphalt.The results show that interaction temperature, CRM content, mixing speed and reaction time have significant influence on the performance of CRM binders. In fact, the interaction of CRM binders is a complex reaction under the action of all factors rather than an individual effect. The optimal parameters of rubber asphalt are the interaction temperature is 190℃, the CRM content is 20%, the mixing speed is 2000r/min and the time is 60 min, which are obtained through optimization evaluation model of asphalt rubber based on TOPSIS method. In general, the mechanical properties of ambient CRM binders are significantly higher than that of cryogenic processing method through the performance tests of different CRM modified asphalt. The viscosity is increased with the increase of the CRM content while the performance of CRM binders with 40 mesh is better than the 30 mesh’s and 80 mesh’s. The FTIR tests show that the cryogenic CRM binders react less violently than ambient CRM binders, which generate new functional groups. However, there do not have any significantly changes of two different binders in LMS value through GPC tests. The binder source has a significant effect on the performance o f the CRM binders. CRM binders produced with Kelamayi always have higher LMS value than those made with SK and Esso and the new functional groups can be found in their FTIR spectrogram. This can be attributed to the severe reaction in CRM binders produced with Kelamayi, which leads to more excellent performance of Kelamayi CRM binders.