Linear and nonlinear viscoelastic parameters of asphalt binders modified with softening agents

Asphalt binder modification using various chemically processed synthetic or bio-based additives can be used to reduce cracking potential in asphalt concrete (AC), especially with recycled materials. These modifiers affect rheological properties of asphalt binders. State-of-the-practice parameters obtained within the linear viscoelastic range (LVER) have not successfully predicted their performance. Using a large-strain amplitude and/or novel small-strain parameters at extended aging conditions (double and triple pressure aging vessel cycles) could help. In this study, parameters for unmodified and modified asphalt binders were studied at various aging conditions. The discussed data supports that: (1) Extended aging allows binder distinction beyond performance grading (2) Intermediate-temperature small-strain rheological parameters of binders may be predicted using low-temperature small-strain parameters, and vice versa. (3) Stiffness-dependent parameters must be interpreted based on temperature and frequency of testing. (4) Δ|G*|peak τ is not correalted to small-strain parameters.