The Effects of Using Crumb Rubber Modified Binder in an Asphalt Pavement

Abstract

In this study, laboratory investigations have been carried out to characterize and demonstrate the improved performance of asphalt after modifying it with crumb rubber. The study has been divided into two main parts. Firstly, the physical characterizations of crumb rubber modified bitumen with different percentages of crumb rubber have been evaluated using penetration, softening point, viscosity, ductility and thin film oven tests. In the second part, Marshall Mix design has been performed for both asphalt rubber and control asphalt. After finding the optimum mix for both of them, Marshall and indirect tensile tests have been performed on both moisture-conditioned and -unconditioned cases to assess their performance in terms of stability, deformation, tensile strength and the effect of moisture on paving mixtures. Control asphalt samples have been prepared for the purpose of comparison. These laboratory investigations have been intended to evaluate utilizing crumb rubber in dense graded asphalt mixtures. Previous studies have shown that gap graded and dense graded asphalt rubber mixes performed better somehow than their respective conventional asphalt mixes. In addition, in Kuwait, gap graded mix is only used for chip seal while dense graded asphalt mix is used for main pavement layers such as wearing course and most of the pavement failures happen in this layer. The comparison between the experimental results of asphalt rubber and conventional asphalt showed that asphalt rubber is significantly better than conventional asphalt in terms of rutting and shear resistance as well as stability.