Evaluation of Foamed Warm-Mix Asphalt Incorporating Recycled Asphalt Pavement for Volumetric and Mechanical Properties

Abstract

This study evaluated mixes obtained from a warm-mix asphalt (WMA) pilot project in Reno, Nevada, in the United States, in which the Ultrafoam® technology was used to produce the WMA. The evaluated mixtures included 15% recycled asphalt pavement (RAP). The study addressed the impact of curing time on volumetric properties of foamed WMA in addition to including a sample reheating study. Additionally, the field-produced WMA mixes were evaluated for moisture damage, permanent deformation and thermal cracking resistance. It was recommended that production testing for volumetric properties should be conducted within four hours of manufacturing foamed WMA at the plant. The mix should be cured in a sealed container at the expected lay-down/compaction temperature. Overall in the laboratory, the WMA mix showed no significant additional reduction in moisture damage resistance although the reverse was true for permanent deformation resistance. The WMA exhibited better thermal cracking resistance than the hot mix asphalt (HMA). A distress survey conducted after thirteen months of service showed no distresses in the WMA pavement despite its relatively lower rutting resistance observed in the laboratory.