Comprehensive study on the applicability of evaluation index for rubber modified asphalt rheological property

The rheological properties of asphalt binder have significant influence on pavement performance. Although the researches on rubber modified asphalt rheological properties are available in some references, the applicability of evaluation index for rubber modified asphalt rheological properties has not been studied thoroughly. For this reason, this study meticulously evaluated the applicability of rheological evaluation index for asphalt containing different rubber particle size through the high-, medium- and low-temperature rheological tests, and focused on the influence of thixotropic behaviour on rubber modified asphalt fatigue resistance. Furthermore, the comprehensive influence of rubber particle size on asphalt rheological properties was revealed from quantitative perspective. Here we showed that the rubber improved the creep recovery and rutting factor of asphalt, while worsening the irrecoverable creep compliance. Thixotropic behaviour would cause modulus measured in indoor test not to faithfully reflect the asphalt fatigue process. It was recommended that the times of loading corresponding to the 50 % reduction in modulus without considering the effect of thixotropy was adopted as rubber asphalt fatigue resistance index. The glass transition temperature and the index that simultaneously considered relaxation capability and modulus were suggested to assess rubber asphalt low-temperature resistance. The different rubber particle size had various effect on asphalt rheological properties, where the asphalt containing 40 mesh rubber presented the optimum rheological behaviour. The comprehensive exploration of rubber asphalt rheological behaviour provides useful guidance for the promotion and application of rubber materials in asphalt pavement.