Performance Evaluation of Crumb Rubber-Modified Asphalt Mixtures Based on Laboratory and Field Investigations

Research studies often propose additives to improve the mechanical properties that extend pavement service life by reducing the rate of permanent deformation of conventional asphalt mixtures. However, questions remain regarding the consistency and efficacy of additives compared to the conventional mixtures, particularly under different conditions of loading and climate inherent to various countries and locations. To shed further light, this paper presents a laboratory and field evaluation of Marshall and Superpave Gyratory-compacted crumb rubber-modified and traditional asphalt concrete mixtures. A laboratory-based study was conducted to ascertain the resilient modulus, indirect tensile strength, and permanent deformation of crumb rubber-modified asphalt mixtures. The Marshall stability and resilient modulus of mixtures prepared with crumb rubber-modified mixtures were increased on average by 30 and 43%, respectively, as compared to the control mixtures, whereas the permanent deformation of the crumb rubber-modified mixtures was improved on average by 12% in contrast to the control mixtures. Field investigations on short-term effectiveness revealed crumb rubber-modified asphalt mixture treatment exhibited on average 36.16% drop in International Roughness Index. In contrast, the control mixture pavement showed 24.20% drop in International Roughness Index. The results indicate and quantify the extent to which crumb rubber improves the performance of the conventional mixtures, in terms of the performance criteria specified.