Properties of warm mix asphalt from two field projects: Reno, Nevada and Manitoba, Canada

This study was geared towards evaluating the properties of warm mix asphalt (WMA) mixes that were obtained from two field projects; Reno, NV and Manitoba, Canada, in the laboratory, relative to conventional hot mix asphalt (HMA) mixes. The former field project utilized the Ultrafoam RTM WMA technology to produce the WMA mixes while the latter used the AdveraRTM zeolite technology. The evaluated mixtures also included different percentages of recycled asphalt pavement (RAP). Generally the study addressed the impact of curing time on volumetric properties of foamed WMA; impact of sample reheating on the mechanical properties of WMA; and evaluation of the resistance of WMA mixtures to moisture damage, permanent deformation and thermal cracking. From the study, it was recommended that production testing for volumetric properties should be conducted within four hours of manufacturing the WMA at the plant immediately after discharge. The mixes should be cured in a sealed container at the expected lay-down/compaction temperature. Overall, the resistance of WMA mix to moisture damage was found to be WMA technology-specific and also dependant on whether or not antistripping additives were incorporated in the mix, all other factors being constant. The resistance to permanent deformation of WMA was generally found to be satisfactory whereas the WMA out-performed the HMA in terms of thermal cracking resistance.