This article discusses the rheological tests and analyses based on the Schapery non-linear viscoelasticity model that were performed to study asphalt mastic behaviour under high shear stresses. Seven mineral filler types were applied in this study, including a mixed filler with hydrated lime and fillers derived from dust extraction systems. Determination of basic properties of the fillers was followed by creep and recovery tests (DSR) at different levels of shear stress conducted in accordance with a modified MSCR procedure. The first stage in the analysis was the identification of linear viscoelastic region and the non-linear viscoelasticity model parameters such as the length of the loading period, the temperature and the stress level using TTSSP (Time-Temperature- Stress Superposition Principle). Subsequent numerical simulations of strain variation with respect to stress confirmed a high degree of agreement between the non-linear viscoelasticity model and mastic sample behaviour. A strong correlation was found between the non-linear viscoelasticity parameters and mastic properties. The proposed methodology is able to quickly identify and eliminate the fillers that may contribute to HMA deformations.

The paper’s objective was to present the results of predicting the stiffness modulus of a recycled mix containing a blended road binder with foamed bitumen and emulsified bitumen. The Sm (acc. to IT-CY) indirect tensile test was used at temperatures of -10°C, 5°C, 13°C and 25°C. Prediction of the stiffness modulus accounted for the effect of temperature, the type of road binders, the sampling location and the type of technology selected. All effects, except temperature, were included in the model by entangling their effects through recycled base course physical and mechanical characteristics, such as indirect tensile strength, compressive strength, creep rate, air void content and moisture resistance. As a result, it was possible to determine a regression model based on multiple regression with a coefficient of determination R² = 0.78. Temperature and compressive strength were found to have the strongest effect on the variability of stiffness modulus. However, indirect tensile strength also significantly affected the Sm characteristic. In addition, FB-RCM (foamed bitumen) recycled mixtures proved to be more favourable than EB-RCM (emulsified bitumen) mixtures as they exhibited a lower deformation rate while retaining limited stiffness.