Combustion mechanism of four components separated from asphalt binder

To study the combustion mechanism of four components separated from asphalt binder, combustion properties of each component and their dynamic evolution of released volatiles were discussed, respectively, and then the morphology and chemical compositions of combustion residues were analyzed. Results indicated that combustion reactions of saturates, aromatics and resins include thermal decomposition of each component and oxidation combustion of charring layer, but asphaltenes only includes oxidation combustion of charring layer. Further, four exothermic volatilizations and endothermic reactions occured alternately during combustion of both saturates and aromatics. Combustion reactions of aromatics were more intense and its thermal effects were more obvious than those of saturates. However, only two and one exothermic peaks were found during the combustion of resins and asphaltenes, respectively. The total heat release amount of each component was increased from saturates to asphaltenes. Additionally, the dynamic evolution and constituents of released volatiles from each component were different. CO2 and H2O were the most important products during the combustion of each component. Gram-Schmidt analysis also further validated the dynamic evolution of released volatiles during the combustion of each component. All these were benificial to further understand the multi-stage combustion characteristics of asphalt binder. Finally, the morphologies of combustion residues of four components are different due to complicated endothermic volatilizations and exothermic reactions. Combustion residues of saturates, aromatics and resins mainly contained C, O and a small amount of heteroatoms, while combustion residues of asphaltenes contained less C and more O and heteroatoms. Combustion properties of asphalt binder are better understood from a new perspective of its component combustion.