Effect of crumb rubber degradation on components distribution and rheological properties of Terminal Blend rubberized asphalt binder

The degradation of crumb rubber modifier (CRM) was confirmed to affect the rheological properties in the production Terminal Blend (TB) rubberized asphalt binder. However, the quantitative analysis on the components distribution of TB rubberized asphalt binder and correlations to rheological properties were not investigated yet. The present study was to investigate the effect of CRM degradation on components distribution and rheological properties of TB rubberized asphalt binders produced under various curing temperatures and 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. Brookfield viscometer and Dynamic Shear Rheometer (DSR) were used to investigate the viscosity properties, rutting resistance and rheological behaviour at wide frequencies. The results indicated that interaction time played a similar role as interaction temperature did in promoting the dissolution of CRM whereas the breaking of backbone of the main chain of rubber was more dependent on interaction temperature. With the gradual degradation of CRM, the workability and storage stability were improved with the sacrifice of rutting resistance. In addition, the enhance effects of CRM on |G∗| values at both lower and higher frequencies and phase angle values at lower frequencies gradually weakened. The evolution of log |G∗| lower asymptote and crossover modulus indicated TB rubberized asphalt binders became softer with the degradation of CRM. The well link between apparent asphaltenes and various rheological parameters indicated that it was the transform of CRM from insoluble components and dissolved polymers to medium size molecules that affected the rheological properties of TB rubberized asphalt binder.