Master curves of crumb rubber modified binders containing Montan waxes as warm mix asphalt additives

Resumen

Energy consumption and the corresponding greenhouse gas (GHG) emissions can be reduced with technology recently developed in the field of road pavement materials: warm mix asphalt (WMA). This technology is being incorporated to improve workability and, consequently, production and compaction temperatures of asphalt mixtures can be lowered without significantly affecting their mechanical properties. However, since this technology is relatively new, the influence of WMA additives on the properties of crumb rubber modified (CRM) binders has not yet been investigated in depth and clearly identified. The main objective of this study is to investigate the effect of different types and quantities of WMA additives on the high and intermediate temperature properties of a 20%CRM binder. For this purpose, binder´s properties are determined using a dynamic shear rheometer (DSR) which allows elastic, viscoelastic and viscous properties of bitumen to be defined over a wide range of temperatures and frequencies. The results of this study indicate that there are significant improvements produced by the additives concerning the mechanical behaviour and the elasticity for the whole temperature range; the complex modulus (stiffness) is increased at the high temperatures avoiding permanent deformation and the phase angle curve is shifted on lower values over a wide range of frequencies. However, the increased content of additives slightly shifted the complex modulus master curves in high frequency regions, increasing the stiffness at low temperatures