Negative Impacts Of Environmental Factors (Uv Radiation, Water And Different Solutions) On Bitumen And Its Mechanism

The environmental factors, such as the ultraviolet (UV) radiation, water, acid, alkali and salt, can cause significant negative impacts on the bitumen. Therefore, multi-factors coupling ageing test is closer to the actual service conditions of bitumen. Nine groups of coupling-condition ageing tests (UV radiation and the acidic, alkaline and neutral solutions) were conducted on the bitumen (Pen60/80). The conditioning times were 3, 6 and 9 days. After the test, the coupling hazards and its mechanism of these environmental factors on bitumen were analyzed. In detail, the transition of the appearance, physical and rheological properties of bitumen was characterized, the results show that coupled conditions have much more serious negative impacts on the performance of bitumen. In addition, to reveal the mechanism of negative impacts, the chemical functional groups and components of bitumen were studied, meanwhile the pH value, organic carbon content and chemical functional groups of the residual solutions were also analyzed, indicating that the coupled ageing mechanism mainly includes three channels, they are the excitation and break of bituminous molecules, the dissolution and leach of the organic component in the solutions, and the catalytic action of the alkali metal ions. (C) 2020 Elsevier Ltd. All rights reserved.