Mix design and laboratory characterisation of rubberised mixture used as damping layer in pavements

Road authorities are challenged by traffic-induced vibrations due to their detrimental effects on humans and to the damage of buildings and structures. For this reason, asphalt mixtures designed as damping layer are investigated to resist vibration and noise caused by traffic loads, while a reliable design method to optimise for the mixes needs to be developed and their damping and mechanical properties require corresponding evaluation. In this work, a novel mix-design method special for the damping layer is proposed. Two rubberised asphalt mixtures were designed by optimising their damping properties and their volumetrics were adjusted to accommodate a high content of rubberised bitumen. Tensile strength, rutting resistance, stiffness, loss factor, phase angle and damping ratio were measured to evaluate their mechanical and functional potential as thin damping interlayer in road pavements. Results show that the designed mixes have higher damping capacity than traditional rubberised asphalt mixes. Aside from this, the mixes appear to be rut resistant and show sufficient levels of tensile strength and resistance to water damage.