Crumb rubber modifier (CRM) produced from waste tires has been used in pavement engineering for more than half a century. This recycling methodology improves sustainable development because of environmental benefits of recycling scrap tires and because of improved performance of pavement materials when the recycled tire rubber is used as modifier in asphalt binders. This application improves both rutting and cracking resistance of asphalt pavement when an appropriate design is followed.

Adding the CRM to asphalt binders leads to modification of binder properties, including rheological properties and aging resistance. This modification alters pavement performance in-service. Previous studies found that rubber-modified binders had better aging resistance than their base binders. However, the mechanism of rubber modification on aging resistance was not well understood. This study aimed to explore this mechanism for rubber-modified binders. This study also evaluated the performance-related properties of dense-graded asphalt mixes using smaller quantities of CRM than are used in current applications, and their expected performance in different structural applications.