Performance of Rubberized Asphalt Pavements in Illinois - Final Report Author(s): Volle, Tessa H. Origin: Illinois Date: December, 2000 Categories: Performance Key Words: crumb rubber modifier (CRM), rubberized asphalt, wet process, dry process, performance, distress surveys, friction, International Roughness Index (IRI), rut values Summary: In 1991, the Illinois DOT began a program to incorporate scrap tire rubber as a modifier in selected hot-mix asphalt (HMA) paving projects. This effort was a response to the requirements of the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991. In 1995, when the department ended its efforts in crumb rubber modifier (CRM) usage, eleven crumb rubber projects had been constructed. By that time, Section 1038 of ISTEA was modified by subsequent federal legislation and the mandate was repealed. Two methods were used in Illinois to combine CRM with HMA: the wet process and the dry process. Two terms have been used in Illinois to define the various quantities of CRM added to HMA: variable rate and fixed rate. Variable rate defines a small quantity of CRM added to the HMA: no mare than five pounds of CRM per ton of HMA. Fixes rate defines a larger quantity: no less than twenty pounds of CRM per ton of HMA. This reports includes a cost summary in which the final bid prices of HMA containing CRM for each project are compared to costs of conventional HMA in Illinois. However, the main purpose of this report is to summarize the performance monitoring of the eleven crumb rubber modified HMA projects in Illinois through March 31, 1999. Performance monitoring the most of the rubberized asphalt pavements includes the following: visual distress surveys and surface property characteristics.