Feasibility of Crumb Rubber Use for Asphalt Pavement Construction

There are two processes of adding crumb rubber modifier (CRM) to hot mix asphalt (HMA), that is, the wet process and the dry process; and different technologies are available for each process. On the basis of the results of the binder study and producer's practices, HMA specimens were prepared using two selected AR binders with Producer R and A CRMs for Rhode Island (RI) dense-graded and dense-graded friction course (DGFC) mixtures, respectively. Aggregates procured from four local asphalt contractors were used. In addition, gap-graded HMA specimens were prepared with 3 percent CRM and control AC-20 binder with two typical local aggregates using the dry process. Marshall mix design was performed on all mixtures to determine optimum binder content and Marshall properties. Mechanical properties were evaluated for the mixtures with and without CRM. Superpave Level I mix design was also performed for dense-graded, DGFC, and gap-graded mixtures with aggregates procured from Contractor C. Finally, the performance of pavements with and without CRM was predicted using the computer program VESYS. Results of this study indicated that the use of CRM is feasible for RI dense-graded and DGFC mixtures utilizing the wet process.