Study On The Performance Of Rubberized Warm Asphalt Binder And Its Mortar

Using the waste crumb rubber modified asphalt to pave the road surface could protect environmental and save energy, which is an effective way of recycling the non-renewable resources. However, the mixing temperature and compaction temperature temperature of rubberized asphalt binder and its mixture is much higher than those of ordinary asphalt mixtures, resulting in the viscosity at construction temperature is so high that severiously affect the construction schedule. So the paper incorporated the technology of warm mix asphalt into rubberized asphalt to solve the problem, and further carried out indoor testes to test the performances of rubberized warm asphalt binder and its mortar. The paper also put forward some views about the relationship between different low-temperature parameters.The study representatively selected crumb rubber modifier(CRM) of three particle size which were 40 mesh, 60 mesh and 80 mesh and one warm asphalt additive W as materials and used orthogonal diagram of four factors and three levels to arrange the test. Using penetration index, softening point, ductility, viscosity, cerrp stiffness and elastic recovery as evaluation indexes, the study evaluated the effect of crumb rubber particle size, crumb rubber content and W content on the above indexes according to variance analysis (ANOVA) and range analysis. The results showed crumb rubber particle size was the key affecting factor to nearly all the investigated indexes expecting for softening point and elastic recovery, and the changing law of each indicator as the change of particle size was not consistent. It is not necessary that the binder modified with finer crumb rubber has better performance, but the performance of containing 60 mesh is very close with that of crumb rubber of 80 mesh; The impact of crumb rubber content comes second. Besides creep rate m, the other performance get improved as the increase in crumb rubber content; For W, its the primary influencing factor whereas its the most minor factors to other indicators, but the high W content is favorable to high-temperature and temperature sensitivity as well as bad to low-temperature performance slightly. By comparing the performances of rubberized asphalt binder with those of rubberized warm asphalt, it can be seen that the addition of W caused the penetration decreases substantially, penetration index and plastic temperature range increase, ductility at 5℃decreases while softening point increases significantly, viscosity decreases and the decreasing scope show increasing trend with temperature increases. Compared with rubberized asphalt, the mixing temperature and compaction temperature of rubberized warm asphalt reduced by 27℃and 25℃.BBR tests showed that the W was adverse to the low-temperature properties of binders, but the effects became not obvious as the temperature decreases; DSR tests showed that as the increase in test temperature, composite modulus decreased while phase angle increased. Therefore, rutting factor showed signs of a downward trend obviously with the increasing of temperature. It showed that with the rise of temperature, binders gradually transformed from elastic to viscous and it was more easily lead to permanent deformation under load. After adding W, the elastic component of binders increased.The RV, BBR, DSR tests were carried out to study the performance of the two kinds of mortar. Results showed that with the increase in dust proportion and W content, viscosity-temperature index reduced significantly, low temperature X -valuebecame smaller, G~*/sinδincreased in quadratic polynomial law. That is, largerdust proportion and more W content is favourable to lower temperature sensitivity and high-temperature performance. However, it is adverse to the low-temperature anti-deformation capacityThe paper studied the relationships between different low-temperature performance parameters of asphalt binders. After deduction, one physical equation between creep ratio and creep stiffness was established and based on this equation, one method used to compare low-temperature performance of materials was also built. The test results of nine kinds of rubberized warm asphalt (RWA) binders were used to verify the correct of established physical equation and analyzed the correlation between different low-temperature performance parameters. The analysis demonstrated that creep rate and relaxation time, creep rate and dissipation energy ratios, creep rate and stiffness ratio as well as dissipated energy has a good linear correlation. However, delay time and other low-temperature performance, dissipation energy ratio and stiffness has no correlation.