The effect of air-blowing method and blending method in bitumen production on the performance of bitumen and asphalt mixture

Abstract Although the amount of bitumen compared to aggregates in asphalt mixtures is low, it plays an important role in the properties and durability of the asphalt mixture. The purpose of this study is to investigate the role of the bitumen production process in the performance of bitumen and asphalt mixtures. In this regard, three different 60–70 bitumen were prepared with different processes including 1) air blowing of light VB, 2) blending heavy VB and Heavy Vacuum Slops (HVS), 3) blending heavy VB and Vacuum Residue (VR). The physical, chemical, and rheological tests were performed on bitumen. Also, the properties of HMA made with these bitumens, such as resilient modulus, dynamic creep, rutting by wheel track, and tensile strength have been investigated. The results showed that VR bitumen causes greater temperature sensitivity and poorer high and low-temperature properties in bitumen and negatively affects the performance of asphalt mixtures against permanent deformation and fatigue. HVS bitumen, due to its oily structure, provides greater flexibility in bitumen and HMA, especially intermediate temperatures. The results of asphalt mixture tests indicated improved rutting performance (43–86%), fatigue cracking (about 48% and 60%), and moisture sensitivity (7% and 10%) in asphalt mixtures made with bitumen produced by the air-blowing process.