Evaluation and Performance Based Mix Design of Rubber Modified Mixtures.211 Laboratory Evaluation of Asphalt Concrete Mixtures Using Waste Tires

摘要

New Jersey Department of Transportation is being investigating the use of rubber211u001emodified materials over the last years with the design and use of dense and gap 211u001egraded mixtures, and in some cases the incorporation of RAP materials, in 211u001eselected projects. While the short term field performance of these materials is 211u001ebeing satisfactory, their long term performance is unknown. These mixtures were 211u001edesigned with the traditional Marshall mixture design method, and thus is was not 211u001econsidered design criteria related to mixture behavior and performance into 211u001emixture selection. The main objective of this study is the development of a 211u001emixture design methodology for rubber modified materials that considers mixture 211u001ebehavior and performance. In order to achieve this objective a laboratory 211u001einvestigation able to evaluate mixture properties that can be related to mixture 211u001eperformance, (in terms of rutting, low temperature cracking, and fatigue), and 211u001esimulating the actual field loading conditions that the material is being exposed 211u001eto, was conducted. The possibility of coupling the traditional Marshall mix 211u001edesign method with parameters related to mixture behavior and performance was 211u001einvestigated since this technique is being used over the years by the agency, and 211u001ethe necessary testing apparatus is available to both the agency and material 211u001elaboratories. The SHRP SUPERPAVE mix design methodology was reviewed and 211u001econsidered in this study for the development of an integrated performance based 211u001edesign procedure. However, its applicability and use on routine bases was not 211u001econsidered at this time since it requires specific equipment with ongoing 211u001eevaluation for its repeatability and precision. Finally, for the conduct of this 211u001einvestigation materials and mixtures used by NJDOT in rubber modified paving 211u001eprojects were used.