Performance Evaluation of Terminal Blend Tire Rubber HMA and WMA Mixtures-Case Studies

• Autores: ELIE Y. HAJJ, PETER E. SEBAALY, EDGARD HITTI, CORINA BORROEL
• Localización: Asphalt paving technology, ISSN 0270-2932, Vol. 80, 2011, págs. 665-696
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • A terminal blend tire rubber (TR) modified asphalt binder is made using a finely ground crumb rubber modifier that is typically blended and digested into the binder at the asphalt refinery. TR with less than 10% rubber was initially introduced in hot mix applications during the mid 1980s in California and Florida. Since then, it has been used in several other states with increasing amounts of rubber up to 20% as a finished PG-TR binder in recent years. The use of TR asphalt binders in dense graded hot mix asphalt (HMA) mixtures in Nevada has been fairly limited. The main concern for the Nevada Department of Transportation (NDOT) was the lack of performance records for TR asphalt mixtures compared to the outstanding performance of the polymermodified asphalt mixtures typically used in Nevada. This paper summarizes the efforts undertaken in Nevada to assess and implement the use of TR binders in dense graded asphalt mixtures. An extensive performance evaluation was conducted in the laboratory to assess and compare the TR binders to the standard polymer-modified asphalt binders used in Nevada. Subsequently, based on the findings, pilot demonstration projects were constructed in 2008 in Nevada and California with side by side sections of TR and polymer-modified asphalt mixtures. Visual inspections conducted in 2011 of both projects revealed no visual distresses, with the pavement condition being excellent and uniformly the same along the total length of both test sections. Giving this promising field performance of TR mixes, a study was initiated in 2010 to evaluate the use of TR in warm mix asphalt (WMA) mixes. The results for two types of warm mix additives are presented in this paper, Advera® and Sasobit®. Mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles. The study specifically looked into the potential impact of aggregate residual moisture in the mix due to insufficient aggregate drying during production.

    _______________________________ 1Research Assistant Professor, Univ. of Nevada 2Director of WRSC, Univ. of Nevada 3Research and Development Manager, Paramount Asphalt 4Graduate Research Assistant, Univ. of Nevada The oral presentation was made by Professor Hajj.