Influence of warm mix additives on the low-temperature behavior of bitumen using the Bending Beam Rheometer (BBR)

The mechanical and rheological characteristics of bitumen are crucial for the behavior and durability of the bituminous road layers. A bitumen susceptible to high temperatures can lead to plastic deformation of the bituminous layers, whereas a low temperature susceptible binder can lead to cracking of the bituminous layers. The penetration test at 25 degrees C, softening point - ring and ball method and ductility test were carried out on a 50/70 bitumen and five types of bitumen blends. In order to determine the behavior of bitumen at low temperatures, the Bending Beam Rheometer method was implemented. The presented research aims to determine how different additives that have the purpose to increase the workability of asphalt mixtures (for making warm mix asphalts) influence the behavior of a 50/70 bitumen commonly used in Romanian road technique. In this regard, the results regarding the susceptibility of bitumen at low temperatures are presented, compared to those of the same binder in which various additives were introduced. To further highlight the influence that the additives used have on the low temperature behavior of the bitumen, the research is completed by tests on bituminous mastic for each type of binder. The additives do not lead to significant changes in the rheology of pure bitumen. The wax has the biggest influence on the bitumen's properties. The limit temperature increases with the addition of filler in the blends. (C) 2020 Elsevier Ltd. All rights reserved.