Study of the Viscoelastic Performance of Cold Recycling Mixtures with Bitumen Emulsion

To limit reflective cracking in asphalt pavements with cold-recycled base courses, cold recycling mixtures (CRMs) are designed to provide predominantly bituminous bonding, making their viscoelastic behaviour of paramount importance. This study presents an experimental evaluation of the viscoelasticity of CRMs containing 0–90% RAP, 5.5–7.4% bitumen emulsion, and 1% cement. The dynamic modulus and phase angle were determined according to AASHTO T 378-22 across temperatures of 5–40 °C and loading frequencies of 0.1–25 Hz. To assess the applicability of the time–temperature superposition principle (TTSP) for describing the CRMs’ mechanical behaviour, master curves were constructed and the statistical analysis of the model fit quality was performed. The research findings demonstrate that CRMs’ mechanical behaviour can be effectively modelled using TTSP, with their viscoelastic response being influenced by RAP and bitumen emulsion content. CRMs showed lower temperature sensitivity than HMA, yet changes in dynamic modulus and phase angle remained statistically significant. This study advances the performance-based design of CRMs and points to the potential of rheological modelling for their constitutive characterization.