Recycling of laboratory-prepared reclaimed asphalt pavement mixtures containing crumb rubber-modified binders in hot-mix asphalt

The recycling of reclaimed asphalt pavements (RAP) containing crumb rubber-modified binder is an important issue because some of these types of pavements are more than 10 to 15 years old in some areas in the United States. In this study, a laboratory investigation was conducted on the possibility of laboratory-prepared crumb rubber-modified RAP being recycled in Superpave® mixtures according to a normal recycling practice. Six mixtures (three recycled mixtures containing laboratory-prepared crumb rubber-modified RAP and three control virgin mixtures) were designed and tested. Three types of aggregates and two types of crumb rubber-modified binders were used for the mixtures. The crumb rubber-modified RAP used in the study was artificially aged in the laboratory with an accelerated aging process. The percentage of the RAP incorporated into the recycled mixtures was 15%. Evaluation of all mixtures included the following testing procedures: indirect tensile strength, asphalt pavement analyzer, and resilient modulus and gel permeation Chromatograph v. Results from this study showed that (a) it is possible to incorporate 15% crumb rubber-modified RAP into hot-mix asphalt using normal recycling practices and (b) there is no significant difference between the three virgin and the three recycled mixtures in the properties discussed.