Investigation of warm-mix asphalt for Iowa roadways.

PDFTech ReportIHRB Project TR-635InTrans Project 11-406Warm mix paving mixturesPavement performanceCondition surveysService lifePerformance testsAsphalt additivesShinglesRecycled materialsIowaIowa. Dept. of TransportationBuss, AshleyWilliams, R. ChristopherIowa State University. Institute for TransportationUS Transportation CollectionPhase II of this study further evaluated the performance of plant-produced warm-mix asphalt (WMA) mixes by conductingadditional mixture performance tests at a broader range of temperatures, adding additional pavements to the study, comparingvirgin and recovered binder properties, performing pavement condition surveys, and comparing survey data with the MechanisticEmpirical Pavement Design Guide (MEPDG) forecast for pavement damage over 20 years of service life. Further objectivesdetailing curing behavior, quality assurance testing, and hybrid technologies were as follows:\uef\u201a\ub7 Compare the predicted and observed field performance of existing WMA trials produced in the previous Phase I study to thatof hot-mix asphalt (HMA) control sections to determine if Phase I conclusions are translating to the field\uef\u201a\ub7 Identify any curing effect (and timing of the effect) of WMA mixtures and binders in the field\uef\u201a\ub7 Determine how the field-compacted mixture properties and recovered binder properties of WMA compare to those of HMAover time for technologies common to Iowa\uef\u201a\ub7 Identify the protocols for WMA sample preparation for volumetric and performance testing that best simulate field conditionsThe findings of this study indicate that WMA additives do show statistical differences in mixture properties in some of the mixestested. These differences will not always be statistically different from mixture to mixture. Multiple factors, such as WMAadditive type, amount of recycled asphalt material, construction conditions, and mixture variability all play a role in determiningthe extent of which WMA and HMA mixes differ. Other significant findings of this study include effects of curing, aging inrecovered binders from HMA and WMA cores, and the influence of recycled asphalt shingles (RAS) used with WMA. Thesefindings will be of interest to owner agencies and contractors utilizing WMA technologies