Research On Multi-scale Characteristics Of Asphalt Aging And Recycling

Asphalt material is a relatively complex organic polymer material.The aging of asphalt will seriously affect the road performance and eventually lead to road surface question.The current research on the aging process of asphalt mainly focuses on the effect of aging on the road performance and internal chemical components of asphalt,and the interaction mechanism between the macroscopic properties and microscopic properties of asphalt cannot be accurately grasped.At the same time,it also leads to unclear understanding of the mechanism of action between aging asphalt and regenerant,which restricts the popularization and application of asphalt pavement regeneration technology.Therefore,the thesis carried out research on the multi-scale characteristics of asphalt aging and regeneration to provide a scientific theoretical basis for asphalt anti-aging properties and regeneration technology.Artificial simulated aging is used to prepare different degrees of PAV aging asphalt.Through the three major indexes,Brinell viscosity,dynamic shear rheometer(DSR),bending beam rheometer(BBR)test,the basic macro-rheological properties of 70#matrix asphalt and SBS modified asphalt before and after aging were analyzed.The results show that:aging will improve the high temperature performance of asphalt,and the low temperature crack resistance will gradually decline.At the same time,the addition of SBS modifier can alleviate the impact of aging on asphalt performance and improve the anti-aging ability of asphalt.The optimal blending amount of the regenerant is determined by the Arrhenius viscosity blending formula.Under the optimal blending amount of the regenerator,the macro-rheological properties of the asphalt are obviously restored,with certain deviations,but all can meet the specification requirements.This shows that the adverse effects of asphalt aging on performance cannot be ignored.The properties of asphalt after aging and regeneration were studied by atomic force microscopy(AFM)and infrared spectroscopy(FTIR).The correlation among macro,rheological and micro properties is analyzed by using statistical analysis software.The results show that:functional groups have a significant impact on the macro rheological properties of asphalt;because of the fast,accurate,sensitive and simple operation of infrared spectrum detection,it is proposed to evaluate the aging degree of asphalt based on infrared spectrum technology to provide reliable guidance for practical projects;asphalt After aging and regeneration,the change of mechanical properties at macro scale and micro scale presents the same law.The macro mechanical behavior of surface is the embodiment of the change of micro mechanical properties at macro level.The hypothesis of regeneration mechanism of "surface activation theory" is put forward.Based on the micro adhesion and interface analysis,the mechanism between the regeneration agent and aging asphalt is discussed,which shows that the regeneration agent can activate the old The surface performance of asphalt is changed to achieve the purpose of restoring the performance of asphalt.Comprehensive analysis,the thesis adopts multi-scale analysis methods such as macro performance,rheological performance,chemical functional groups and micro characteristics to theoretically explain the relationship between macro,rheological characteristics and micro characteristics after asphalt aging and regeneration.The research on asphalt anti-aging properties and regeneration technology is of guiding significance.