Performance evaluation of dry process crumb rubber-modified asphalt mixtures with nanomaterial

Using crumb rubber (CR), especially at high percentages, in asphalt pavement using dry process has less popularity than wet process due to the adverse effect of this method on adhesion and/or cohesion, causing two principal problems: first, causing poor performance of the mixture (i.e. fatigue and rutting performance), second, causing the mixture more susceptible to moisture damage. This study aims to improve the usage of CR using dry process by modification of binder with nanomaterial namely Zycosoil. For this objective, asphalt mixtures modified with Zycosoil at three contents of 1%, 2.5% and 4% by weight of binder, and CR at three contents of 1%, 3% and 5% by weight of aggregate. The Zycosoil effects on binder properties were investigated by ductility, softening point, penetration, rotational viscosity and dynamic shear rheometer tests. Also, the mechanical properties of mixtures, including moisture susceptibility, indirect tensile strength, stiffness modulus, rutting resistance and fatigue behaviour were evaluated. The results indicate that Zycosoil modification improves the rheological characteristics of binder, causing an improvement in mixtures resistance against moisture, rutting and fatigue damages. Furthermore, the mixtures performance is negatively affected by using high content of CR that this impact is enhanced by Zycosoil modification.