Impacts of WMA Production Temperatures on Binder Aging and Mixture Flow Number

摘要

Implementation of Warm Mix Asphalt (WMA) has generated interestrnat state and national levels due to the potential to realize environmentalrnbenefits related to lower production temperatures. However, from the aspectrnof sustainability, WMA must meet or exceed the performance of conventionalrnHMA. Therefore, successful implementation requires mix design proceduresrnthat consider the impacts of reduced production temperatures on materialrnproperties and the overall performance of the mixture. In this study the effectsrnof reduced aging temperatures were evaluated through characterization ofrnasphalt binder properties after short-term aging at standard and lowered RTFOrntemperatures and long-term aging under standard PAV conditions. Materialsrntested included two asphalt binder sources and three WMA additive types. Itrnwas found that reduced aging temperatures have a significant influence on thernhigh temperature performance of binders, but a negligible effect onrnintermediate and low temperature rheological properties evaluated after PAVrnaging. Results were modeled based on the procedures provided in NCHRP 9-rn43 to define the maximum allowable reductions in production temperature forrnthe materials tested in this study. Preliminary findings indicate that thernpredicted temperature reductions for the FHWA aging model and thernlaboratory generated data set differed by 9rnC, indicating that refinement of thernmodel through evaluation of additional binder sources, grades, and WMArnadditives is needed. Similar sensitivity to aging temperature was observed inrnmixture performance testing, emphasizing the need for establishing minimumrnproduction temperatures for WMA to ensure adequate field performance.