Rheological Properties of Bituminous Binders with Synthetic Wax

Warm Mix Asphalt (WMA) has been introduced to reduce the environmental impact and improve energy efficiency of bituminous mixtures production and lay down. With this purpose, synthetic waxes are effectively used to allow reduction of temperature during mixing and compaction. Given these advantages, the basic WMA challenge is the production of a pavement mixture having, at least, the same performance as traditional HMA. This study describes the effect of a synthetic wax additive on the rheological properties of a paving grade bitumen in a wide range of temperatures. The effect of wax at mixing and compaction temperatures (T > 100°C) was evaluated using viscosity tests. A Dynamic Shear Rheometer (DSR) and a Bending Beam Rheometer (BBR) were used to investigate the rheological properties of the base and the WMA binder at midrange and low service temperatures (from 18°C to 37°C). The time-temperature superposition principle was applied to analyze the complex shear modulus and the creep stiffness modulus, through the construction of master curves. Particular attention was devoted to the study of wax effect on low temperature physical hardening.