Use of Waste Tires (Crumb Rubber) on Colorado Highways.

摘要

The objective of this study was to determine the feasibility of using waste tires (crumb rubber) in the construction of asphalt pavements in Colorado. Two pilot test sections and one control section were constructed and observed over a five-year period to meet this objective. The two pilot test sections were built using two crumb rubber modified (CRM) asphalt processes. One process uses ground tire rubber (GTR) blended with hot asphalt cement at the asphalt plant to form the hot mix asphalt. This is referred to as the Wet Process. The other process blends GTR and asphalt cement at a remote blending facility and is then transported to the hot mix plant to produce the hot mix asphalt. This process is the Terminal Blend method. In addition, a control section was constructed containing a conventional binder. Binders in the two test sections containing GTR and the control section met the specifications for PG 64-28 asphalt. Each of the three test sections contains approximately 1,000 tons of 2-inch asphalt overlay placed over a cold-milled surface in the eastbound driving lane of US 34 Bypass near Greeley, CO. Construction of the test and control sections occurred in the summer of 2009. The goal of this research project is to evaluate the performance of the crumb rubber test sections compared with the conventional control section and depending on performance, develop Colorado-specific materials and construction specifications for ground tire modified asphalt pavements. Also, the research project aims to develop guidelines and best management practices for the construction of ground tire modified asphalt pavements. Transverse cracking began in the rubber modified sections after 22 months of service and longitudinal cracking began after 29 months. The control sections have no transverse cracking to date with longitudinal cracking beginning to appear after 56 months.