ABSTRACT
Warm Mix Asphalt (WMA), the technology that allows significant reduction in the mixing and compaction temperatures, has been commonly used in USA and Europe since the early 2000’s. Although WMA additives decrease these temperatures, in some practices production is maintained without lowering temperatures to increase the compactibility in the field. Therefore, this paper studies the effect of Compaction Temperature (CT) on the mixture stability and volumetric properties. Since Superpave gyratory compactor is not sensitive to temperature changes, Marshall hammer is used for the sample preparation. The test matrix includes a control mixture (HMA) and two different WMA mixtures; prepared with a non-foaming additive (Sasobit) and a foaming additive (Advera). Additionally, two different dosages for each additive are used in WMA samples preparation to observe the effect on the compaction. The mixture properties are limited with one dense gradation and one penetration grade binder. Four replicates of each mixture are prefabricated at four different CT‘s. The temperatures are selected as the typical CT of HMA, 15, 30, and 45°C lower than HMA. Two of the replicates are used to determine the stability of the mixtures and the rest of the samples are used to analyze the gradation changes during the compaction process. Accordingly, these samples are burned in the ignition oven and re-sieved to quantify the degradation of the aggregates during the compaction and mixing. It was observed that WMA is less susceptible to CT changes than HMA and the degradation pattern for these mixtures are similar at different CT’s.
