Description
In 2006, the Illinois Tollway initiated a trial of hot mix asphalt (HMA) surface mixes modified with ground tire rubber (GTR). These mixes originally were intended to improve pavement noise, and they proved to have additional benefits for stone matrix asphalt (SMA) and open graded asphalt mixtures.
In 2007, the Tollway embarked on a field trial and laboratory pavement performance validation of an SMA asphalt surface mixture that uses fractionated recycled asphalt pavement (FRAP) and GTR. This highly recycled material was evaluated during mix design, field production, and laboratory performance testing .The Tollway selected a demonstration project site on a rural interstate highway with high truck traffic, then proceeded with mix designs, field production, and strict quality testing. The mix design and field production documentation shows that GTR-FRAP can be designed and produced with success. The use of GTR eliminates the need for the fibers that often are required using other modifiers. The laboratory evaluation of performance included such tests as dynamic modulus, beam fatigue, stability, rut testing, and tensile strength testing. The results of these tests indicate that the performance of the GTR-modified mixes is similar to other SBS modified HMA mixes commonly used in Illinois. These performance test data are the first validation of the use of GTR and FRAP in SMA mixtures under heavy interstate traffic.modified SMA mixes with
