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Effect of warm mix additives on compactabilitiy of mixtures

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2019
Pamuk, Ömer Can
Warm Mix Asphalt (WMA), the technology that allows significant reduction in the mixing and compaction temperatures of asphalt mixtures, has been commonly used globally since the early 2000s. This study evaluates the effect of compaction temperature (CT) on WMA and Hot Mix Asphalt (HMA) mixtures volumetrics, degradation, stability, and compactability properties. Although both Superpave Gyratory Compactor (SPGC) and Marshall hammer are used for sample preparation, the focus of this study is to develop compactability parameters for mixtures compacted with Marshall hammer, since SPGC is not sensitive to temperature changes. Besides, current compactability related studies are not capable of assessing the influence of temperature changes. Therefore, in this study, an image-based method and a testing setup are developed to obtain the densification/compaction curves. In order to analyze the effect of CT, the test matrix includes one HMA and four different WMA mixtures; prepared with a non-foaming additive (Sasobit) and a foaming additive (Advera) at two different dosages. CT’s are selected as the typical CT of HMA (140 °C), 15, 30, 45 °C lower than this temperature. It was concluded that pavements constructed with WMA additives at lower temperatures could meet the performance of HMA pavements constructed at traditional temperatures. In addition, the degradation patterns are similar for WMA and HMA mixtures. Finally, the compactability parameters calculated from Marshall densification curves meet the known field behavior of WMA and HMA mixtures, whereas it is not possible to drive the same relations from the parameters calculated from SPGC compaction curves.