Reduced Permanent Deformation of Asphalt Pavement by Enhancing Aggregate Gradation

摘要

Permanent deformation (rutting Phenomena) of asphalt mixes is considered as one of the major forms of distress that affects the performance of flexible pavement structures. Many factors can cause permanent deformation to occur in asphalt mixtures, but aggregate gradation is one of the key factors responsible for this deterioration. In this study, aggregate structure was designed using the Bailey method. Eight aggregate gradations were used to analyze their effect on rutting resistance of asphalt mixtures. Three additional mixes were then designed using Styrene Butadiene Styrene (SBS) as a modifier to improve the rutting resistance. Three percentages of SBS, namely (2 %, 4 % and 6 %) by weight of asphalt cement, were mixed for 60 min at a temperature of 180°C using a shear mixer with a rotation speed of 3000 rpm. The asphalt mixtures were subjected to rutting test using a wheel tracking device at an air void level of 4% corresponding to optimum asphalt content. The results showed that the Bailey method maintained good resistance to permanent deformation as compared to conventional mixes. Overall, mixes with coarser gradation (Bailey Parameter, CACUW, greater than 95 %) and 4% SBS modified asphalt produced more resistance to rutting.