Relationship between colloidal index and chemo-rheological properties of asphalt binders modified by various recycling agents

This paper examines relation between colloidal index (CI) and chemo-rheological properties of asphalt binders modified by five different recycling agents (RAs) including paraffinic oils, aromatic extracts, naphthenic oils, triglycerides/fatty acids, and tall oils. To monitor the change of binder properties, each binder was exposed to different aging conditions. Saturates, aromatics, resins and asphaltenes content of each modified binder, as well as its rheological and low-temperature cracking properties were determined before and after aging. It was found that recycling agents could vary the softening and long-term performance of the modified binders based on their chemical makeup. While all RAs softened the binder, only few could restore binder rheological properties. The study results revealed a strong linear relation between the CI and the chemo-rheological properties of binders. For instance, the flexural creep stiffness and Log complex modulus found to inversely related to CI while the phase angle and relaxation constant (m-value) found to be directly related to CI. The study results highlight the source dependency of RAs’ efficacy to restore and maintain binder properties after aging.