Evolution of components distribution and its effect on low temperature properties of terminal blend rubberized asphalt binder

The addition of crumb rubber modifier (CRM) could enhance the low temperature properties of asphalt binder. However, in the production of terminal blend (TB) rubberized asphalt binder, the degradation of CRM results in the change of molecular components of TB rubberized asphalt binder. The effect of components evolution on low temperature rheological behaviour of TB rubberized asphalt binder was not clear yet. The present study aims to investigate the evolution of components distribution and its effect on low temperature properties of TB rubberized asphalt binders produced under various interaction temperatures and interaction times. The solubility test and the Gel Permeation Chromatography (GPC) test were performed to obtain the distribution of insoluble components, dissolved polymers, apparent asphaltenes and maltenes in various TB rubberized asphalt binder. Bending Beam Rheometer (BBR) was conducted to investigate the low temperature properties of TB rubberized asphalt binder before and after aging. Burgers model was used to retrieve the relaxation time at low temperature. The results indicated that interaction time plays a more important role in promoting the dissolution of CRM whereas the interaction temperature is more responsible for the breaking of backbone of the main chain of rubber. Low temperature stiffness of TB rubberized asphalt binder increased with the degradation of CRM, which has a negative effect on low temperature performance. Relaxation property of TB rubberized asphalt binder was improved with the increase in percentage of apparent asphaltenes. However, the loss of relaxation property of TB rubberized asphalt binder after aging is more remarkable with the gradual degradation of CRM. TB rubberized asphalt binder investigated in the present study exhibits better low temperature performance than styrene-butadienestyrene (SBS) modified asphalt binder and base binder. The parameter ΔTc increases linearly with the reduction of insoluble components and dissolved polymers, which indicates that the low temperature property is becoming less m-value controlled with the degradation of CRM.