Study On Anti-aging Performance And Mechanism Of Warm Mix Rubber Asphalt Under The Action Of Heat Oxygen Water

Evotherm warming agent and Sasobit warming agent can improve the pavement performance of rubber asphalt road surface,but the asphalt pavement will often be affected by rain,air,ultraviolet and load during actual use of the process,which makes the asphalt pavement prematurely disease and seriously affects its normal service life.Therefore,in-depth study of the aging mechanism of warm mix rubber asphalt can provide a certain reference significance for the design and maintenance of warm mix rubber asphalt pavement in the warm and humid environment of the south.According to the high temperature and rainy climatic environmental of Guangdong Province,this paper considers three factors of heat,oxygen and water,and conducts aging simulation tests on warm mix rubber asphalt mixed with Sasobit warming and Evotherm warming.The conventional performance test is used to study the differences in macro performance of warm mix rubber asphalt,and also commented on its temperature sensitivity.The thermodynamic analysis?TGA?is used to study the pyrolysis characteristics of warm mix rubber asphalt before and after aging,and by means of Fourier Transform infrared spectroscopy?FTIR?and Atomic Force Microscope?AFM?are used to study the changes of chemical functional groups,microscopic morphology and mechanical properties of warm mix rubber asphalt before and after heat-oxygen-water aging.Research indicates:?1?After warm mix rubber asphalt suffers from heat oxygen water aging,the small components inside the asphalt undergo volatilization and transition to large molecules.Moreover,chemical composition shows that the content of saturation and aroma is reduced,and content of asphaltene and colloid is relatively increased;In terms of macro performance,the penetration is reduced,however softening point,ductility and viscosity is increased.?2?The penetration index can not truly reflect the temperature-sensing performance of warm mix rubber asphalt,and the penetration index viscosity index and viscosity temperature index should be used for evaluation,The temperature sensitivity of Sasobit warm mix rubber asphalt after heat oxygen aging is greater than that of Evotherm warm mix rubber asphalt.?3?The combined action of heat-oxygen-water makes warm mix rubber asphalt more prone to"oxygen-absorbing"oxidation reactions.The characteristic functional group of hydroxyl?-OH?,Aliphatic methyl?CH₂?and methylene?CH₃?,carbonyl?C=O?,The sulfoxide?S=O?content is increased,and water will dissolve some of the aging products,which causes the hardening phenomenon of the interface between asphalt and water.?4?The pyrolysis process of warm mix rubber asphalt can be divided into three reaction stages with obvious thermal hysteresis,and exist an certain thermal hysteresis,Morover,it can be obtained that Sasobit warm mix rubber asphalt has better thermal stability than Evotherm warm mix rubber asphalt.The Coats-Redfern integration method,Kissinger integration method,and distributed activation energy model?DAEM?are feasible to simulate the pyrolysis kinetics of warm mix rubber asphalt.The Coats-Redfern integration method can be expressed by a first-order dynamic reaction to obtain the activation which between 20k J/mol?30k J/mol;the Kissinger integration method and the DAEM model have similar activation energy,and their values are between70k J/mol?180k J/mol.And the activation energy will increase first and then decrease as the conversion rate increases.?5?The activation energy shows a tendency of increasing first and then decreasing with the increase of the conversion rate.In the apparent morphology of warm mix rubber asphalt,there is no typical“bee phase”structure,but a“cracked”structure.The number of“cracked”structures increase after heat oxygen water aging.heat-oxygen-water immersion aging reduces the roughness of the surface of warm mix rubber asphalt,while heat-oxygen-water vapor aging results in increased roughness;Both heat-oxygen-water immersion aging and heat-oxygen-water vapor aging can increase the DMT modulus of warm mix rubber asphalt,reducing its adhesion,work and surface energy,and the anti-aging properties of Sasobit warm mix rubber asphalt are better than Evotherm warm mix rubber asphalt in adhesion performance.