Evaluation of the degree of blending and polymer degradation of reclaimed asphalt pavement (RAP) for warm mix asphalt

The paving industry has seen the emergence of a plethora of warm mix asphalt (WMA) technologies and applications in recent years. With most state transportation agencies incorporating a recycled asphalt pavement (RAP) usage requirement, it is necessary for WMA to not only serve as a greener technology, but to work in conjunction with current RAP practices. The purpose of this study is to develop a methodology for quantifying the degree of blending that occurs in warm mix asphalt-RAP mixtures that include higher percentages of RAP. In addition to the methodology, the degree of blending will be determined for WMA and hot mix asphalt production temperatures as well as other varying pre-paving conditions like mixing time, conditioning time, and WMA type. The degree of blending proved to be sensitive only to the mixing time condition and did not display any trends or significant differences for any of the other conditions tested. Polymer degradation of WMA was also studied to determine whether lower production temperatures could decrease polymer degradation. Polymer degradation was decreased at lower production temperatures; however, greater polymer degradation was observed to occur when warm mix asphalt binders were subjected to hot mix asphalt conditioning.