Mutual changes in bitumen and rubber related to the production of asphalt rubber binders

Asphalt rubber (AR) mixtures are currently a material with an increasing use in road pavements due to their improved performance and environmental benefit of recycling rubber from used tires. AR binders have been widely applied, but the bitumen and rubber interactions remain poorly understood. The aim of this work is to quantify and correlate the changes in bitumen and rubber during AR binders’ production, in order to characterize the interactions between the AR constituent materials, e.g. residual bitumen and recovered rubber. A good correlation between the rheological and physical changes in the properties of rubber, bitumen and AR binder was observed.

► Mutual changes between the bitumen and rubber during AR production are evident.
► Good correlations between bitumen and rubber changes for Pen lower than 100 dmm.
► The performance of AR binder at high temperatures is independent of rubber changes.
► Residual bitumen changes are effectively identified with the rheological τ index.
► Final properties of the AR depend more on residual bitumen than on rubber changes.